Entering autos: discussion split from Glasgow crash thread

[PeteGillies]

Gentlemen –
This is my first post to PPRuNe. It concerns the tragic accident at Glasgow on November 29. I have read all of the over-800 posts regarding this accident and feel that I may be able to shed some light on what David Traill faced as the helicopter headed down.
The Best Kept Secret in the helicopter industry is how critical it is to immediately apply aft cyclic the moment a loss of power to the rotor system is detected. I have been doing my best to spread this word since analyzing the cause of two law-enforcement helicopter accidents that occurred four months apart in 2002. I call it Cyclic Back.
Very few helicopter pilots realize that if, with a total engine failure, the rotor rpm is allowed to fall more than about 5% below low green, the flight is over. OVER. There is no recovery possible regardless of what actions the pilot may take or how high the helicopter is above ground. This fact is not mentioned in the sales literature for helicopters nor in the approved rotorcraft flight manuals. It is not mentioned in any of our FAA publications having to do with how helicopters fly and how to fly them. It is treated as a deep dark secret, unfortunately.
When power is lost to the rotor system, THE MOST IMPORTANT FLIGHT CONTROL IN THE COCKPIT IS THE CYCLIC! It must immediately be brought aft so that the flow of air is upwards through the rotor system. Bottoming the collective does only one thing: It reduces the rate that the rotor rpm is falling. That’s all! It NEVER stops the fall of rotor rpm.
Once the rotor rpm has dropped below the critical point, recovery is not possible. The helicopter continues to descend as the rotor rpm falls towards zero and may, in the case of free-turbine engines as used in the EC135, be seen to turn backwards. The rotor blades will show little if any damage when the wreckage is examined.
And as the rotor rpm slows towards zero during the descent, retreating blade stall enters the picture. The normal Vne chart does not mention rotor rpm; it is assumed it is normal for the standard mode of flight. But when rotor rpm falls, Vne falls with it, so Vne is very possible at airspeeds much below those computed via the chart.
This in turn means that as the rotor rpm is falling during the autorotation, the helicopter will roll in the direction of the retreating blades, or to the left in the case of the EC135. Any attempt by the pilot to correct this with opposite cyclic simply adds additional pitch to the blades that are already stalling, thereby increasing the amount of roll.
When a helicopter pilot is faced with a sudden unannounced engine or drive-line failure, here is what must be done:
1. Cyclic back and pitch down, simultaneously or in that order.
2. Pick a place to land.
3. MAKE THAT SPOT!
What about indicated airspeed. At the beginning of the autorotation, the ONLY speed that matters is that over the wings, meaning, of course, the rotor blades, and this is a function of rotor rpm. Pitot tube airspeed (indicated airspeed) is not important at that time, but yes, once the rotor rpm is solidly in the green, indicated airspeed can be helpful in extending the glide or reducing the rate of descent.
Finally, this: During a normal power-off autorotation, the helicopter will respond to all flight-control movements the same way it would if the helicopter is in a flat-pitch descent with the engine running. The only thing it won’t do is a sustained climb. But it will stop, back up, turn in any direction, etc. So when I say MAKE THAT SPOT, I’m saying use the maneuverability of the helicopter just as you would if the engine was running. There is more to life than straight-ins, 90s and 180s!
Based on what I have read so far on PPRuNe, my thoughts are this: For whatever reason, both engines went off line one following the other, but Dave did not apply aft cyclic quickly enough to prevent the rotor rpm from falling below that critical point from which recovery is not possible.
Pilot error, you say? Not at all. Dave did exactly what he was trained to do in this sort of emergency. The blame goes to the simple fact that the critical importance of applying aft cyclic quickly when power is lost to the rotor system has been kept from all of us since rotor blades were invented. Cyclic Back must become an integral part of all helicopter training and publications. This must not remain a secret any longer!
I extend my most sincere condolences to everyone who was directly affected or touched in any way by this most unfortunate accident.
PeteGillies

[Munnyspinner]

Peter Gillies, thank you for a helpful and, to me, very plausible description of possible events. I am not a rotor head but would like to think I understand enough to appreciate your theory.
The reason the power was lost in the first place remains a mystery but AAIB are the only people that will resolve that riddle.
Thanks for your insight and your patience in reading all postings!

[gordon field]

Thank you Peter Gillies for your very clear and concise comments.

[Arkroyal]

Peter Gillies's post is most interesting.

Having personally flown nothing more modern than an AS355N I have no idea how these rigid rotors react in auto, but I'm willing to believe his theory. Don't know how much use it would be from a hover though.

The most important nugget to draw from his post is that once NR falls below critical, the flight is OVER.

From then on the pilot has control which very rapidly diminishes to zero, and there is no input to any control that will alter the trajectory and final impact site.

[G0ULI]

Peter Gillies post gives a very plausible reason for loss of control after a double engine failure. Since the AAIB report indicates that there wasn't an immediately obvious mechanical failure and that there appeared to be sufficient fuel in the tanks to return safely to base, what could cause the engines to fail.

My question is, are their any 'forbidden' attitudes when fuel levels are low, although no low fuel indicator lights are illuminated? For example if the helicopter adopted a steep nose up or nose down attitude, or banked sharply, would the fuel feed pipes be exposed to air above the fluid levels in the tank(s)?

[cattletruck]

The Best Kept Secret in the helicopter industry is how critical it is to immediately apply aft cyclic the moment a loss of power to the rotor system is detected.

The transition from normal stable flight to stable autorotation flight has always been a messy affair requiring the application of lots of inputs quickly. Nr drops, nose drops, nose yaws, body rolls all of which must be fixed quickly and it can be fixed easily enough. We tend to generalise this maneuver when we talk about it by only mentioning lowering of the collective but what we really mean is going from one mode of flight into another. I'd like to think this wasn't a secret to this experienced pilot.

[Whirlybird]

Dave did exactly what he was trained to do in this sort of emergency. The blame goes to the simple fact that the critical importance of applying aft cyclic quickly when power is lost to the rotor system has been kept from all of us since rotor blades were invented. Cyclic Back must become an integral part of all helicopter training and publications. This must not remain a secret any longer!

????? Since when has this been a secret? I learned it when doing my PPL around 16 years ago. "Down, right, back" as my instructor put it over and over again, referring to collective, pedal, and cyclic, but meaning that I should do all three together. Everyone else learned this too. As an instructor, that's what I learned in my FI course, and subsequently taught. It's in all the books. It's common knowledge. No secret, and I find it ABSOLUTELY impossible to believe an experienced police pilot didn't know about it and do it. :confused::confused::confused::confused:

[widow18]

Peter Gillies
Really don't agree with your theory. When we did practice auto entries in the BK 117 they were done from the most probable scenario, that is the pilot pulling power off the incorrect engine. We first simulated a single engine failure, then reached up (overhead throttles) and reduced the second engine to idle, then reached back down and reduced collective to address the RRPM light and horn.
No flare, and no rotor stall. I have done this exercise many times, and the instructor who did the checks would have done it innumerable times. Had he felt there was such a problem he would undoubtedly have mentioned it.
High hover zero speed autorotations, admittedly I have only done in high inertia machines, close throttle, collective down and forward cyclic, further unloading the rotor. Dive for a bit then aft cyclic and flare, pitch and cushion.
Never considered rotor stall in entry
Further to the discussion, if the accident aircraft was 1.5 NM from the pad he was probably no longer in cruise flight but beginning a gentle deceleration.

[Thomas coupling]

Page 61 of this thread should be pulled in its entirety after what Peter Gillies posted. It was followed by a load of bollo*s from newbie pruners some who actually admitted they new little or nothing about helos but liked his theories.
Munneyspinner / GordonField and that extra special contribution from...wait for it: Gouli. Mmmmm

Whirlybird is right - what secret?? :ok:

Let me clarify - for the sake of every helicopter pilot in the WORLD, that what Peter Gillies has stated requires a health warning. Let me set the record straight so helicopter pilots around the world are NOT confused after reading the rubbish he has just pushed out.

IN THE CRUISE:

If you experience a total engine(s) failure you lead with collective down followed with aft cyclic IF you need to. The reason for doing it in that order is because the down collective contains the decaying Nr and the OPTION to select aft cyclic provides you with the choice to go for range or not. Selecting aft cyclic without a second thought means that after you have done this and THEN find you won't make your spot you have to reselect fwd cyclic to gain range. The important part of this above statement is LEAD with collective and NOT aft cyclic.

HOVER:

Absolutely under NO circumstances whatsoever do you lead with aft cyclic- PERIOD.
In the hover after sustaining total engine(s) failure you lead with down lever. You ALLOW the attitude of the a/c to nose down. Down lever contains decaying Nr and nose down allows you to gain fwd speed which in 'most' cases is what you want.
If you lead with aft cyclic in the hover and then follow with collective you will enter a whole new world of hurt.


These above processes have been tried and tested - probably hundreds of thousnads of times in training and in real life scenarios.
There is no SECRET :=:ugh: Never has been ...never will be.

Does Peter Gillies honestly think 99% of all helo pilots out there are harbouring a myth? Does he honestly think there really is some "secret" being kept from end users about this. Stop reading your Marvel mags PG and join the rest of us in the real world.:*:*:*

[HeliComparator]

TC - a little harsh, and as or more misleading than PG! Clearly, in the hover or low speed, aft cyclic would be wrong. I don't think PG was trying to say it was needed, he was in his own mind just covering the case of being in the cruise etc.

As for the cruise case, perhaps it depends on the type. In the case of the Super Puma family with which I am familiar, lowering the collective lowers the nose slightly. If you floor the collective without moving the cyclic, everything flies up to the roof as the g falls below zero. Zero or negative g means no significant autorotational effect and the Nr plummets whilst IAS increases. After a while and once the rate of descent has built up the g bites and the Nr rockets up from too low to above max in about 1 second. It is a most horrendous way to enter autorotation for both its effect on the aerodynamics and the disorientation that negative g brings to the pilot.

You say lead with the collective to contain Nr, but dumping the collective does not arrest the Nr decay, you need aft cyclic as well (from cruise speed) to do that. Yes dumping the collective will eventually restore the Nr but it will have decayed much further, especially if the entry is unexpected, possibly beyond the point of no return, if aft cyclic is not applied.

By contrast a simultaneous aft cyclic movement makes it all a benign and gentle manoeuvre. From cruise speed, little or no airspeed is lost on entry, you are still well above best range speed even into a headwind so your point about airspeed and best range is plain wrong. If you enter autorotation from around Vy, less or no aft cyclic is needed of course, but then most people spend most of their time in the cruise, not flying around Vy.

[llamaman]

From PeteGillies:

When power is lost to the rotor system, THE MOST IMPORTANT FLIGHT CONTROL IN THE COCKPIT IS THE CYCLIC! It must immediately be brought aft so that the flow of air is upwards through the rotor system.

Total nonsense when applied to the high-hover scenario. A simultaneous lowering of collective and application of FORWARD cyclic to accelerate to a suitable autorotative speed would be a more appropriate response (assuming you had enough height to achieve forward airspeed).

In all cases the cyclic and collective are equally important. Collective lowered to preserve Nr and cyclic to determine a suitable speed and direction towards your nominated landing point.

Slight thread drift I know but I thought it important to quash spurious advice!

[Old Age Pilot]

Re: Peter Giles' post #1205

Well kept secret??

Your statement implies to the many non-pilot types reading it that actually knowing how to fly a helicopter is a well kept secret from the pilots actually flying them!

Lowering the Collective and moving the Cyclic back go hand in hand!
Any pilot worth their salt will know how aerodynamics go, and more so will know what to do and when.

I would not wish to fly with a pilot who considers this a well kept secret!

Presumably anyone writing posts in reply, to the effect of "Thank you for your insightful words and revelation into the most surprising secret of helicopter flying" are not helicopter pilots.

In fact it has always been a well known fact that you have very little time to get RPM under control in the event of power loss to the Rotor System. And of course the flight is over if there is no RPM. After all, it is the turning of the Rotor that make a helicopter fly. It's a bit like saying "Do you know? If your car leaves the road and enters the air, your drive is OVER" - well of course it is; your wheels are no longer on the road! :{

[HeliComparator]

OAP - you'd better not fly with TC then!

[Chris Scott]

Forgive me, but can someone explain to this fixed-wing pilot precisely what PeteGillies is recommending in the following statement?

1. Cyclic back and pitch down, simultaneously or in that order.

Does he mean "pitch-down" in the sense of the a/c attitude, or is he referring to the collective lever?

(BTW, not planning on trying to fly a heli any time soon!)

[DOUBLE BOGEY]

Helicomparitor. I agree 100% with your last post. By the time most of us have recognised what has happened, aft cyclic is definitely required almost simultaneously. I think PGs post is a little naive thinking we do it know this but technically sound.

I do not have much experience on smaller helis anymore but I do remember a 500 foot hover throttle chop exercise in the B206 OPC required for filming. Lever fully down, nose fwd for some speed leading to immediate flare" cannot remember the heights/speeds associated with the fare though. 'twas exiting but not too difficult even for me!!

DB

[Thomas coupling]

Helicomparator: PLease please do me the courtesy of reading my post very carefully. DO NOT add words that did not exist in the original script. I have chosen my words carefully. I chose the word: LEAD not DUMP. Do you understand the difference between the two and why the use of the word 'dump' (apart from the obvious!!) would lead to all sorts of confusion in the cockpit.
The descriptions are simply explained, they could not be more succinct I would suggest but adding strange volatile words like "dumping the collective" will of course trash the purpose of my message.

You know and all of us know that the physical act of initiating the immediate actions after an engine(s) failure is done in a co-ordinated and smooth fashion whether we are in the hover or cruise. Whether one selects aft cyclic or retain its present position is a matter of choice (IN THE CRUISE) dependent on reaching the landing spot, but (a) it is NOT compulsory to select aft cyclic and (b) it is dangerous to do so from the hover.

Your comment about Old Pilot are inaccurate, yet again you fail to read what is written correctly. At NO point does he mention AFT cyclic...................in fact what he talks about is the aspect of this procedure being kept a secret. C'mon now HC read carefully please?

Double Bogey....Interesting comments:
Helicomparitor. I agree 100% with your last post. By the time most of us have recognised what has happened, aft cyclic is definitely required almost simultaneously. I think PGs post is a little naive thinking we do it know this but technically sound.

I do not have much experience on smaller helis anymore but I do remember a 500 foot hover throttle chop exercise in the B206 OPC required for filming. Lever fully down, nose fwd for some speed

Fascinating......

[chopjock]

TC

IN THE CRUISE:

If you experience a total engine(s) failure you lead with collective down followed with aft cyclic IF you need to. The reason for doing it in that order is because the down collective contains the decaying Nr and the OPTION to select aft cyclic provides you with the choice to go for range or not. Selecting aft cyclic without a second thought means that after you have done this and THEN find you won't make your spot you have to reselect fwd cyclic to gain range. The important part of this above statement is LEAD with collective and NOT aft cyclic.


I thought you knew what you was talking about until I read this.

If I was in the cruise, 125Kts in my 500 and the donk quit, I would most certainly not lower the collective until slowed to at least 80 Kts. I would be pulling in aft cyclic first.

[ShyTorque]

PG Tips:

I hope fixed wing pilots also learn the world's second best kept secret of not pulling back on the control column while attempting to recover from a stall.

Seriously, if all these pilots you know haven't already learned the basics of helicopter control, who is training them and do the FAA know what is going on?

[Back at NH]

I hope fixed wing pilots also learn the world's second best kept secret of not pulling back on the control column while attempting to recover from a stall.

Sadly, AF447 would prove otherwise.

[ShyTorque]

Chopjock,

If I was in the cruise, 125Kts in my 500 and the donk quit, I would most certainly not lower the collective until slowed to at least 80 Kts. I would be pulling in aft cyclic first.

And if was flying at 155 kts in my twin, I would lower the lever slightly and carry on straight and level. It will fly at 125 kts on one engine.

Problem here is that some are trying to find "one size fits all" advice. The correct actions for one aircraft may differ from another. The actions in one set of circumstances need to be quite different for the same aircraft in different circumstances.

[SilsoeSid]

SP,
Can we have another thread split please. Either on autorotations or aviation secrets.
I would like to read about issues directly related to the threads title and the new developments, rather than this tittle tattle.
Thanks




By the way chopjock, if that was you in your 500 over the weekend in S. Warwickshire, please fly a little higher in future, as when your donk stops, that certainly wasnt high enough in the event of... to avoid the town, no matter how much speed you may think you can trade for height by aft cyclic.

[ShyTorque]

Sadly, AF447 would prove otherwise.

Surely, lack of stall recognition was the problem in that tragic case.

[G0ULI]

Thomas Coupling
G0ULI (golf zero uniform lima india) happens to be my radio callsign, although I admit it might be deemed unfortunate in the context of this subject. I have fixed wing flying experience and attended the scene of a fatal light aircraft crash in a professional capacity many years ago, which prompted a lifelong interest in flight safety. I was mystified as to what set of circumstances could cause an apparently perfectly functional helicopter to fall out of the sky. It would seem from the answers in this forum and information elsewhere that something such as a vortex ring formation could in theory put a helicopter in such an attitude that the engines would stop from fuel starvation and in that event, the pilot would have very little time to recover the aircraft. I never knew that the main rotor rpm had to be constrained to within such tight limits or fully appreciated that a full main rotor stall would be unrecoverable irrespective of altitude. This thread has been most enlightening, irrespective of some of the irreverent comments. I have had several opportunities over the years to take a flight in a police helicopter, I never took up the offer, although friends thought I was mad not to. I will stick to fixed wing aircraft.

[HeliComparator]

... Whether one selects aft cyclic or retain its present position is a matter of choice (IN THE CRUISE) dependent on reaching the landing spot, but (a) it is NOT compulsory to select aft cyclic ...


Semantics aside, I disagree strongly. It is "compulsory" to select aft cyclic following a double or second engine failure in the cruise, certainly in all the types I have flown, in order to a void a very messy, disorientating and severely sub-optimal emergency entry into autorotation. If you are suggesting that the pilot should look around to determine the best landing site, before initiating the correct actions to enter autorotation, sorry but that is a seriously dangerous practice.

To the decryers it is relevant to this thread. I maintain that IF the pilot was faced with a simultaneous and unexpected double engine failure, the chances of a successful entry into autorotation are fairly small due to the reaction time of someone accustomed to flying twins, and the very short time one has to get it right in a low inertia heli such as the 135. Especially if said pilot had been taught by TC to evaluate whether range, normal or short auto was required before moving the cyclic!

[Whirlybird]

Perhaps a better way of describing this "aft cyclic" thing is as my very experienced FI course instructor put it..."HOLD the attitude". That means you hold the attitude you need for what is happening with the helicopter and what you plan to do next. After engine failure at altitude in a small helicopter, when the nose will almost definitely drop or be about to, that means aft cyclic. In the hover it doesn't, and with larger helicopters with more inertia, fixed rotor systems etc...well, I'll leave that to those who have far more hours flying them than I do.

The really, really important point is that ALL helicopter pilots KNOW about this! You learn it from Exercise 7 of the Private Pilot's syllabus. You practice it over and over again. You re-learn it every time you convert to a new type, learning the differences (if there are any) for that type. It's not a secret in any way, in fact it's emphasised and practised to such an extent that some instructors feel it's overdone and we should do more stuff about other emergencies instead . There is absolutely no chance at all that the pilot in this accident didn't know precisely what was recommended for engine failure in his helicopter. Peter Gillies, I don't like being this hard on anyone in public, but you got that completely WRONG!!!!

Now that's sorted, can we get back to the main topic of the thread. Please!

[SASless]

Brother bastOn speaks the Truth!



....worrying about a rrpm overspeed should be the last of your worries, the more rrpm when it comes to that final - one chance only - pull up on the collective the better.

As I have said on many occasions here....

"Limitations are for NORMAL Operations"!


There is NOTHING Normal about Crashing!

[PeteGillies]

Gentlemen –
Thank you for your responses, both pro and con, regarding my emphasis on applying aft cyclic as well as collective down at the first sign of loss of power to the rotor system.
Yes, I call it the best kept secret in helicopters because very few helicopter pilots and instructors realize that not catching the rotor rpm before it drops below the point of no return is the end of the flight. The airplane equivalent is that of losing a wing in flight. Not a good way to fly.
Modern flight schools have been teaching a coordinated entry to training-type autorotations for years. Apply enough aft cyclic to restore the airframe attitude to what is was before the entry was initiated. Perfect. And in the relative sanitary situation that exists during flight instruction, with a CFI monitoring the actions of the student and demonstrating the correct performance of the maneuver, this works well. By sanitary I mean that the flight is conducted within a school atmosphere. All actions are predictable, there is a good place to land if needed, and mistakes can be caught before they turn into an emergency.
This is often not the case in the real world. If you believe that every helicopter pilot is expecting an engine failure at any moment during a flight, you are mistaken. Cyclic Back is dedicated to the hundreds, if not thousands, of helicopter pilots flying all over the world today who have never heard about Cyclic Back and are flying with earned confidence in their aircraft. And then wham. The engine quits without warning. These are the pilots I am addressing, not the freshly groomed perfectly trained pilots graduating from flight schools today.
This forum and the posts regarding the EC135 accident are excellent for the most part. The fact that Dave and his passengers contacted the roof with zero rotor rpm says something. The AAIB has already ruled out a seized main-rotor transmission or equivalent. The engines were not running on impact. So how can the helicopter end up descending with the rotor rpm going down to possibly zero?
Easy. As I said in my earlier post, allowing the rotor rpm to drop below the critical point with no engine power to bring it back into the operating range will cause this to happen every time. No exceptions. And as I said before, there is no recovery from this situation. None.
Notice how all of the flight manuals and training related publications emphasize bottoming the collective at the first sign of an engine failure. They don’t say how much or how rapidly to lower the collective. Just do it, and if the rotor tends to overspeed, pull enough pitch to keep it in the green.
Applying aft cyclic should be done the same way. Just do it. If it was not necessary, then fine. No harm done.
I smiled when I read the posts saying that Cyclic Back was not a good thing to do in a hover, high, low or otherwise. Well, duh. Of course not. Nor is it needed during a low power descent where air is already passing upwards through the rotor disc. It applies directly to the helicopter in powered forward flight, where the pilot is caught completely by surprise with an engine or drive-line failure. Or maybe the pilot is not caught completely by surprise as in the out-of-fuel non-survivable crash of an EMS helicopter in Missouri on August 26, 2011. In any case, if the cyclic is not brought back in time, the rotor rpm continues dropping and can never be stopped or recovered.



Part of our company is our Part 141 flight school in operation since 1980. During that time we have given initial, advanced and recurrency flight training to helicopter pilots of all levels of skill and experience, and we have repeatedly seen high-time professional pilots either do nothing with the cyclic, or worse yet, push it forward, when power was quickly reduced to idle. And the majority of recurrency training has been with law enforcement and military- trained pilots.
Oh, and the noises heard by some witnesses to the crash of the EC135 could have been caused by one or both engines attempting to reignite during the descent.
Finally, this: If you have access to the July 2013 issue of Aviation International News, look for an article about Cyclic Back in the letters to the editor section of the magazine.
Thank you, gentlemen, for allowing me to contribute my thoughts to this perplexing and very unfortunate accident.
Pete Gillies

[ShyTorque]

Yes, I call it the best kept secret in helicopters because very few helicopter pilots and instructors realize that not catching the rotor rpm before it drops below the point of no return is the end of the flight

Rubbish. It's no secret. You're obviously meeting the wrong sort of helicopter pilots.

[Arkroyal]

Absolutely Shy Torque.

That was drummed in to me very early on in helicopter training, and passed on to my students later on.

I can't imagine any uk military trained helo pilot not knowing this, and would expect his civilian counterpart to be similarly aware.

It ain't called critical RPM for fun.

[Whirlybird]

PeteGillies, you are quite unbelievable. You're talking, in the main, to a bunch of very well qualified and experienced pilots here, not complete rookies who know nothing whatsoever about helicopters. You're being condescending to the point that I wonder....are you for real?

Finally, please don't assume we're all "gentlemen"; some of those of the other gender have been flying helicopters for quite a long time.

[HeliComparator]

Well in PG's defence I have been caught out by a recently trained pilot who entered a practice autorotation in an EC225 (aircraft, not Sim) by flooring the collective without moving the cyclic. We didn't even take the engines back to idle! Anyway, after I had scraped myself off the cockpit roof I just had time to grab the collective as the disc "bit" and the Nr went wild with the Nr gauge rotating nearly as fast as the rotors! I yanked up the collective and caught it right on the max transient power off Nr limit, above which it would have been head change time.

Others have been less aggressive with the lowering but still unaware that they should move the cyclic back when doing this from the cruise. So his point is valid and whilst you can poo poo it if you know it already, you should be aware that there are some professional pilots out there who don't know it. I know that for a fact!

And don't forget that quite clearly our own TC doesn't know it, nor presumably do his students.

[ShyTorque]

HC, the comment to which I said "rubbish" was not about what the pilot does in the simulator, it was about an alleged basic flaw in theoretical knowledge and training. Read my post again and look at the relevant quote from PG. I stand by that response. If what he says is true, there is a basic flaw in the way that pilots are trained in the USA.

That apart, from my own time instructing on rotary wing and fixed wing, both in the air and in the sim (I ran an RAF helicopter simulator project some twenty years ago), what a pilot knows and what he does on a particular aircraft type may not be quite the same thing - at least, not until he's had a few goes at it. That's what training is actually for - to get used to the best way to fly a particular aircraft type, not to see how bad they are when they begin the training session!

[HeliComparator]

Just a question. Are you suggesting that some heli pilots are not trained to cyclic flare in forward flight following engine failure? Are they trained purely to lower the collective?



I don't know what they are trained to do, but it seems that not long after qualifying they have either forgotten it or never knew. Whether it is relevant that many of our pilots now train in the USA, I don't know.

[HeliComparator]

... If what he says is true, there is a basic flaw in the way that pilots are trained in the USA.




Judging by the FAA's own documents, that may well be true.

[ShyTorque]

Could trying to gain even a tiny bit of height to clear the top of this building cause a rotor stall?

Once established in autorotation it isn't possible to gain height without a significant reduction in rotor rpm, if at all.

[Wetbulb]

"Yes, I call it the best kept secret in helicopters because very few helicopter pilots and instructors realize that not catching the rotor rpm before it drops below the point of no return is the end of the flight"

Many pilots and training facilities will find this statement insulting.

What you say is certainly not reflective of my experience in the UK. During my private and commercial licence training and the instruction I've received during annual checks etc (at various training facilities around the UK) I never found instructors to be as naive as you suggest or training to be as weak as you suggest.

I think your advice, whilst well founded, is too generalised across aircraft types and flight emergency scenarios and you should adapt it a bit.

It sounds a bit like your motivation is to create a niche about which to write a book.

[check]

Back in the 70's I experiences 3 engine failures in single engine helicopters, 2 in a Bell 47 and 1 in a Bell 205. I have tried reliving those incidents but all I can confirm is lowering the collective. What I did wth the cyclic was automatic, slight nose down from the hover, reduced airspeed with the night failure and turned to avoid obstacles in the 205. All different. cyclic movements.

One was during a 100 ft hover while observing a gunnery shoot along a tree line, another during night cross country training and the third in the 205 on finals to a helipad.

What I'm trying to say is you cannot fly the aircraft by numbers, with the correct training you will react instinctivly, and by the time you breathe out you will be set up either for landing or continued flight.

[Ornis]

No matter what the fuel gauges were reading, the cause of this crash was not fuel exhaustion.

There are some things you have to practise until they are instinctive. No thinking. For an aeroplane: Too slow, nose down. Others I call "mantras". One is: If the engine stops? Think: Turn the fuel on. Silly? Read the light aircraft crash reports.

Surely the first thing a student rotary-wing pilot learns is the wings must move to fly. Certainly a fixed-wing student pilot knows. No rotor rpm in a helicopter is the equivalent of an aerodynamic stall in a tail-heavy aeroplane?

Peter Gillies' discussion. I am not surprised it created a furore. But the proof of the pudding is in the eating. This aircraft was not autorotating when it went through the roof.

Faulty gauges. Was the pilot misled into thinking it was fuel exhaustion when it was fuel starvation? That is, unregistered "hidden" fuel in the main tank but none in the supply tanks. Faulty gauges and faulty pump at the same time?

[Thomas coupling]

Mr Gillies: I have to read and re-read your posts to fully grasp your message and I am going to suggest that there is a disconnect caused by translation between the american and english language. :ouch: [Does that sound condescending too?].

Statements like:
very few helicopter pilots and instructors realize that not catching the rotor rpm before it drops below the point of no return is the end of the flight. The airplane equivalent is that of losing a wing in flight. Not a good way to fly are bordering on the ridiculous. If you really have to broadcast this detritus please qualify it by pointing it at your fellow american pilots and not us europeans. Because, believe me - every professional pilot I have ever met has this ingrained in their DNA.

Reading back, I think we can reach an understanding as it is down to semenatics and also the way you have phrased it:

Thank you for your responses, both pro and con, regarding my emphasis on applying aft cyclic as well as collective down at the first sign of loss of power to the rotor system.

The correct (global) way to enter an auto after engine(s) failure is to lower the collective first (not dump it as HC keeps referring in all of his posts), followed by and this is the seminal point MAINTAINING attitude. The time frame between lowering of collective and cyclic input may be minimal but it is always done in this strict order: collective 1st and cyclic 2nd.
Some may say - ah, got you: To maintain attitude always requires aft cyclic. NOT the case...it all depends on where your LZ is.
Now if you don't believe me then take a look at DAPT's link to the FAA web site and read up on engine failures/autos. This is what the Feds are recommending to all their pilots:

At the instant of engine failure, the main rotor blades are
producing lift and thrust from their angle of attack (AOA)
and velocity. By lowering the collective pitch, which must be
done immediately in case of an engine failure, lift and drag
are reduced, and the helicopter begins an immediate descent,
thus producing an upward flow of air through the rotor
system. This upward flow of air through the rotor provides
sufficient thrust to maintain rotor rpm throughout the descent.
Since the tail rotor is driven by the main rotor transmission
during autorotation, heading control is maintained with the
antitorque pedals as in normal flight
Several factors affect the rate of descent in autorotation:
density altitude, gross weight, rotor rpm, and airspeed. The
primary way to control the rate of descent is with airspeed.
Higher or lower airspeed is obtained with the cyclic pitch
control just as in normal powered flight. In theory, a pilot
has a choice in the angle of descent varying from a vertical
descent to maximum range, .

Pilots should practice autorotations with varying airspeeds
between the minimum rate of descent to the maximum glide
angle airspeed. The decision to use the appropriate airspeed
for the conditions and availability of landing area must be
instinctive.

Cyclic input has a great effect on the rotor rpm. An aft cyclic
input loads the rotor, resulting in coning and an increase in
rotor rpm. A forward cyclic input unloads the rotor, resulting
in a decrease in rotor rpm. Therefore, it is prudent to attain
the proper pitch attitude needed to ensure that the desired
landing area can be reached as soon as possible,.

I think I now know where you are coming from PG, you simply have to be more succinct about what you mean and how you post it [:rolleyes:].

And no more silly remarks about the bleedin bloody obvious re Nr decay.:D

[HeliComparator]

TC well done for downloading the FAA doc - I baulked at 20 mB and an .exe file!
Anyway, it is interesting:

By lowering the collective pitch, which must be
done immediately in case of an engine failure, lift and drag
are reduced, and the helicopter begins an immediate descent,
thus producing an upward flow of air through the rotor
system.

Note my different emboldening to yours. The statement is reasonably true when flying at modest speeds, or even flat out in a Bell 47! However it fails to take account that at high speed (by which I mean a modern heli doing 150 kts) the small pitch change that results from the collective being lowered has a huge impact on the g loading. Yes it makes the helicopter descend rapidly, but it does not produce an upward flow of air through the rotor system, at least in the short term.

So in fact that document is wrong, probably outdated from the days when helicopters max speed was not that high - the technique probably worked then.

You say to maintain the attitude, yes I can go with that, certainly better than just dumping :rolleyes: the collective. But a slight pitch nose up will result in less reduction of Nr compared to maintaining the attitude. My point is that this last thing is the most critical, especially in a twin where double engine failures and the need suddenly and unexpectedly to have to enter auto is a much less than once in a lifetime event. There is a good chance of being stunned into inactivity for a moment.

First priority is to keep the rotor rpm in a flying range. If you fail at that first hurdle, you can forget a landing zone.

Yes, once that is in hand, the second and much lower priority is to choose a good landing site and try to make it. But if you get that bit right, but not the first priority, you are wasting what little remains of your life.

Put simply, flaring the aircraft slightly increases your chances of surviving the unexpected auto entry and that is all that matters. (all this of course from cruise flight)

[cattletruck]

Look at it another way.

Most of us have an endorsement on some kind on a teetering head machine. We know that if we let the machine head towards zero g (or enter head banging mode) the rotor disk is then free to do as it wishes and often wants to bump the mast and detach itself.

When the g's are decreasing in forward flight most of us instinctively load the rotor with cyclic, not collective - it's ingrained, and it is regardless of what type of rotor head is fitted by the manufacturer. Even those with FW endorsements already know that secret :E.

[chopjock]

TC
The correct (global) way to enter an auto after engine(s) failure is to lower the collective first (not dump it as HC keeps referring in all of his posts), followed by and this is the seminal point MAINTAINING attitude. I'm sorry I do not understand this. If you are cruising at 150Kts and both donks quit, maintain attitude? Well what is the max range autorotation speed all about then?
I'm sure it's not 150Kts.

[John Eacott]

Guys, one size does not fit all. Zotting along at <50 feet there is no way that my reaction is going to be 'lower the lever' after a loss of power. I'll be pulling the cyclic back to get a bit of height plus convert speed into Nr, then sorting out further actions like collective, etc. If I'm in an OGE hover (or slow speed at height) I'm going to get the cyclic forward to pick up airspeed as well as dropping the lever, totally different reaction.

Autos are energy management; you have three lots of energy (height, airspeed and Nr) to manipulate and arrive safely on the ground. How you manage that is dependent on many factors and there is no initial reaction that fits all of the possible entry scenarios.

Dogmatic posts such as the OP don't seem to have grasped that reality.

[topendtorque]

When the g's are decreasing in forward flight

Seems you have the wrong phallic-sy in hand. Think about it for a tad.

cheers tet

[cattletruck]

tet, I meant in the context of no engine power, I think that's what you're refering to, please forgive me I failed sarcasm :\ :O.

[FH1100 Pilot]

First of all, PHI has been teaching that "Cyclic Back" thing since the 1990s. In Recurrent Training the instructors taught us that our first response to an engine failure in cruise was to start the cyclic coming back...get the nose up...then lower the pitch.

And so I come down squarely with Pete Gilles and HeliComparitor on this. If the engine fails in cruise you must not merely - as Whirlybird huffily suggests - bring the cyclic back to just maintain attitude. Rather, you must get the nose up above the horizon to get the relative wind underneath.

If you're humping along at cruise and the engine quits, lowering the collective will introduce a strong nose-down tendency. The helicopter will immediately start to descend. Bringing the cyclic aft to maintain the cruise attitude will do nothing to correct this; you're still coming down. You have to bring the cyclic even further aft...get the nose up to get the rotor into autorotation. If you're flying a helicopter that cruises faster than it autos, why *not* take advantage of its ability to maintain altitude after the engine failure as you look for a place to land? Why not?

Now, if you're cruising along up at altitude it probably doesn't matter which you do first. If you push the collective down and see the RPM decreasing, your normal instinct will be to load the rotor with aft cyclic. Hey, you have time...what's the diff?

But what if you're dogging along down low...down at 500 feet, or lower, as many pilots do? You might not have an exact spot picked out for your auto (the auto that you're not really anticipating anyway). Trouble is, you neither have the time nor altitude to spare getting the thing set up for an auto. Every foot of altitude is precious. From 500 feet, lowering the collective without a corresponding large aft cyclic input is guaranteed to start an immediate descent. That could seriously limit your choice of landing zones, depending on the terrain.

I was puzzled at the infamous crash of that EMS ship in Missouri back in 2011. I was puzzled because the NTSB said it hit the ground so quickly after the engine quit. I think the NTSB figured that it was about nine seconds or thereabouts from engine failure to impact. And I thought, "How could that be? There's always time. Isn't there?"

I suspect that the pilot was probably frantic. He absolutely knew he was running out of fuel. His landing area (the airport) was in sight but the field boundary was still about a mile away. By this time he'd probably and involuntarily started a descent. So he was probably low...really low. He was screaming along, with the nose down and the rotor at a nose-low attitude toward the relative wind. Then it quit. His first response was to...to text his girlfriend that he'd be late for dinner...wait!...no!...no time for that!...just lower the collective!! Only that put him in an unexpected nose-down descent which was apparently not recoverable.

So Pete and HC, I'm with you guys. Stay the course! But I'll add that - from cruise now...if you don't want to descend - you not only have to make an aft cyclic input to *maintain* attitude, but get the cyclic further back and get the tip path plane tilted *up* and get some air underneath the disk.

[G0ULI]

It appears to me that everyone is in agreement that if the engines stop, the collective lever is lowered and appropriate movements of the cyclic control need to be made immediately. The exact order that this is done and the extent of the control movements necessary depend on the type of helicopter and the flight regime at the time. The key to a successful autorotation seems to be that the control inputs are made within only a couple of seconds depending how close the helicopter is being operated to the avoidance curves. Given a couple of hours flying at night, base in sight, perhaps a bit of chat going on with the observers, you're chilled and relaxed and suddenly both engines stop. How many helicopter pilots could honestly say that they would have mantained control and performed a successful autorotation to the ground? Given the apparent reliability of twin engined helicopters generally, it surely would take at least a couple of seconds to suspend disbelief at what had just happened before the brain engaged and corrective action was initiated, by which time it is too late. That doesn't address the question of what caused the engines to stop suddenly, but given the circumstances known so far, I'm fairly convinced that very few pilots would have managed a survivable landing. For the purposes of this statement, just assume that getting the helicopter anywhere on or in the vicinity of the ground with the cabin intact would do. The links to the helicopter flying manual and other documents have been very informative, thanks to everyone who has posted those.

[Adroight]

I had the good fortune to train at a time when almost all return flights to the training airfield were autorotations to the ground with the engine at idle. We became quite proficient.

These days the only autorotaions I do are in the simulator once a year from 3000', day VMC, runway straight ahead with plenty of warning and 9/10 times the Nr drops to the low 80%'s before recovery and occassionally I still mess up the landing.

I would not like to imagine a scenario of losing both engines at night at 1000' over a city in a steep turn.

[xlsky]

If you're flying a helicopter that cruises faster than it autos, why *not* take advantage of its ability to maintain altitude after the engine failure as you look for a place to land? Why not?

that makes sense even for a FW pilot
makes even more sense if cruising a heli at higher speeds at low altitude..

I would not like to imagine a scenario of losing both engines at night at 1000' over a city in a steep turn

The Scottish police heli operated quite often below 500ft over the City and especially the deprived areas to keep the ned's under control. especially Friday nights. Sometimes below roof top height of the tower blocks. I believe they do some random patrol on the way back from called missions until fuel gets low.

[Nigel Osborn]

I fail to see why an EOL will be any different if the helicopter has 1 engine or 2 engines or 3 or more engines if they are all stopped. A Wessex 5 autoed the same as a Wessex 1, a Bell 205 much like a bell 212 & a Bolkow 105 much like most non bell singles. Once you are good at autos, it hardly matters what the helicopter is.

Pulling back the cyclic in the cruise sounds stupid to me, why slow down if you needed to go faster for range for example. Get into the auto & then see what your best options are.

[Mick Strigg]

On raising the collective, a helicopter pitches nose up. On lowering the collective it pitches down. This is due to the differential of lift across the disc and the effect of the airflow on the horizontal stabiliser.

therefore, on entering autorotation, you have to apply aft cyclic to prevent the nose pitching down.

Try it!

[madflyer26]

Perhaps HC is correct and a lot of civilian pilots going onto become commercial pilots don't understand the potential of the cyclic flare during the entry into autorotation. Dick Sandford agrees and his article would testify to that.

MSA Mornington Sanford Aviation articles "Enough skill to kill yourself" (http://www.morningtonsanfordaviation.com/articles/Enough-skill-to-kill-yourself.html)

During my PPL skills test in Scotland I was shown a low height high speed auto where the very experienced ex military examiner never lowered the collective at all until the speed was at 60 knots. I am sure some on this forum know the gentlemen I am on about. I am grateful I was shown this as I can attest that none of the instructors prior to him demonstrated this or explained it!

Peter is fundemenatlly correct but perhaps using the big paintbrush will offend some.

Regards
MF26

[ShyTorque]

The discussion here has shown that the op's claim (use of cyclic) is no secret. It's only when and how much that's' worth arguing about.

[sunnywa]

When I was a QFI at the (then) ADF Helo School in Canberra, we used to teach the students combinations of cyclic and collective movements to enter auto dependent on the circumstances, and each to an EOL in a AS350BA.
The most fun one was 50ftAO at 100kts when we wound back the throttle. Initial action was to freeze collective and flare to the nose was about 10NU and we would shoot skywards up to about 250ft (the theory being to get as much height as you can to find a good place to park). After the att was NU, we slowly reduced the collective to maintain the Nr. At 70kts, lower att (lever fully down by now) to adopt normal 65 kt auto att. Nr horn would blare as the anti flare from the non violent bunt lowered the Nr, but approaching 150ft, first bite into flare and Nr would come up nicely, horn would silence, and into normal flare to land.
Another type of LL auto would be a level one at 50ft when you flared to maintain height and used lever for Nr control then final hook into flare to land.
For normal cruise flight auto entries, normally lever down slowly and att raise to get the Nr back into the green, then when flying again, look around for pad. At auto spd att adjust and manoeuvre as reqd.
I don't think you can be prescriptive one way or the other but depends ont eh circumstances.
I think the priority should be to control and contain the emergency and (in this case get the Nr back up into the green however you can, combination of both lever and cyclic) then look around for options (safe flight in auto going somewhere you want).
I have found all these posts quite fascinating as it shows that, even after all these years of flying helicopters, there are so many different opinions as to how to do it correctly. Sometimes there are many wasy to skin a cat.

[HeliComparator]

sunnywa, your ways seem eminently sensible to me!

[Savoia]

It will be interesting to see comments from people with real world experience.


Complete engine failure, Bell 206 (belonging to Team Lotus founder Colin Chapman) in September 1980, flying at 120kts (approx.) at 900ft (due to low cloud). We were on our way to Imola in Italy (the only year the Grand Prix was not hosted at Monza). PPRuNer TRC, accompanied by the late great John Ackroyd-Hunt, flew to Norfolk within two hours of the incident as part of the post-engine failure response/rescue.

My godfather was engrossed in the business of unfolding maps when ..

- There was a kick in the aircraft's yaw
- I heard the engine wind-down
- The engine-out caution warnings illuminated and sounded
- My godfather let loose of his maps and assumed control of the aircraft

The response to autorotation was something of a joint venture in that in the second or two which passed between feeling the aircraft yaw, to the moment my godfather assumed control, I was already applying corrective rudder and making cyclic adjustments to maintain a level attitude. These adjustments happened instinctively .. you could perhaps say 'automatically' in that my hands and feet were actively 'engaged' with cyclic and rudder so that when the aircraft's profile was affected by the loss of power, it was 'natural' to correct them.

As my left hand was on my lap at the time of the engine failure .. and given my godfather's 'lightning' response .. he was the one who initiated the reduction in collective .. but, as it happened, an adjustment to cyclic input took place fractionally before he lowered collective and which, as I say, was instinctive in that the 'natural' response (when flying by visual reference) to an uncommanded change in attitude (at least for me) was that you instinctively sought to correct this.

My godfather went on to perform what I can only describe as being a 'perfect' zero-forward-speed touchdown across the furrows of a deeply ploughed field without so much as a scratch on the little Ranger (oh .. I mean JetRanger).

What I can say, following this experience, is that whatever happens immediately following an abrupt and complete loss of power is completely reactionary. If you were to say to yourself "Oh my, how odd, what is going on here" .. that would be too late (at least in a single below say a height above ground of around 1,000ft) .

I was astonished, and I mean astonished, at how quickly everything happened. One moment we were in the cruise .. then .. about 60 seconds later we were on the ground in a field in the middle of what seemed to be nowhere .. in a helicopter with its rotors having almost completed their wind-down. I remember it was extremely quiet after we landed.

Single-engine pilots are trained to continually identify prospective landing areas along their journey's way but .. even with this instinct fully aroused .. once you are faced with a 'live' engine failure it works a little differently to the 'theorised' procedure. The first response is absolutely and unequivocally that of 'sorting-out' the aircraft; regaining controlled attitudes and regulating Nr. As you are doing this you are looking at where you are going to go (not where you would like to go). Depending on your height (we didn't have much) the radius of autorotational flight can be startlingly limited.

Though my godfather taught me to fly from an early age, I had to receive formal training for my initial licence and which task fell to late great Sqn Ldr Anthony 'Antonio' 'Nobby' Clarke who Dennis 'Denissimo' Kenyon had installed as Chief Flying Instructor at his new operation at Booker in the early 80's.

I have to say that Tony taught a 'collective down' policy (as indeed did the late Colin Bates former Chief Pilot of Air Hanson and with whom I flew a base-check in the former Ferranti 206 G-AZZB). But, in both cases, they taught 'attitude control' (meaning cyclic input) as a measured response according to the 'profile' of the auorotation, ie. was it a long or short distance auto, were there turns, was it steep/shallow etc.

This emphasis on preserving (and thereafter controlling) Nr through a reduction in collective (in my mind at least) assumed that cyclic input would be commensurate with the 'automatic' changes in aircraft attitude following a loss of power and which in practice (as per the real life event described above) is what happened.

One needs also to recognise the subtle differences between simulated and actual emergencies. In simulated autorotations you know precisely where you will land. When you encounter an unexpected actual engine failure you do not (at least not to begin with). In simulated autorotations you are 'prepared' (and in most cases with hands and feet fully engaged with all controls) whereas with an actual engine failure you are not specifically prepared any may not have 'active interface' with the flying controls. As mentioned, my left hand was on my lap in the scenario described above but .. it could have been different. Colin Chapman's 206 (because of the frequent travel to European Grand Prix) was fitted with a Collins 3 axis autopilot. Mercifully .. I had not engaged it for the cyclic-mounted disable switch was only available from the right-hand seat (which I was occupying) and not from the dual cyclic where my godfather sat. Having to disable the autopilot from the panel would have been an unwanted and I would add .. dangerous distraction in our particular scenario although I am sure that my godfather would have pushed through the autopilot's breakthrough force had he been required to do so.

In summary:

* In a single engine when experiencing a real life power failure (or I suppose even a twin with a simultaneous double-engine power failure) the preservation of Nr is critical.

* This is accomplished by means of manipulation of the flight controls in which a reduction of the main rotor pitch is essential to sustain autorotation and where adjustments to cyclic input will affect the quality of that autorotation.

* At a height of 1,000ft or less, the radius of autorotational flight is limited and in an actual 'event' the number of suitable landing locations can be similarly limited (unless you happen to be over a level and open area).

* In a real life scenario, you will select your landing area only once you have regained control of the aircraft and are established in autotation.

* While practicing simulated engine failures overhead an airfield at a prepared height one can execute all manner of 'autorotational gymnastics' such as 180° turns and the like (and which at the time seem effortless), in an actual engine failure scenario your 'option' of available landing areas will be 'presented' to you and one of the first things you discover is that time is not on your side.

* During an autorotational descent you will manipulate the aircraft by means of high/low Nr to shorten/extend autorotational range and by means of cyclic inputs (and corresponding pedal adjustments) such as are necessary to set-up the aircraft to perform an arresting flare in front of (or overhead, depending on zero-forward speed touchdown or run on) the landing area you have identified.

* Everything is going to happen faster than you imagined.

I grew up with the knowledge that my godfather was an accomplished aviator and had heard many fascinating recollections of 'brave flight' between him and his former test flying colleagues (the likes of Peter Wilson, Sox Hosegood and Donald Farquarson to name but a few) but .. on that day in Norfolk I gained an enduring respect for his flying abilities.

He was quiet literally unfolding our route maps at the time, to the point that they obscured his forward field of view so that when the engine failed he (initially) had no awareness of what lay ahead. From this totally unprepared condition he assumed control of the aircraft and executed, as mentioned, a perfect autorotation.

But, I will say again, even for him, it was 'instinctive' and I would add .. in an actual emergency is when your training will shine through. It is actually impressive to see how the 'mind and body' can respond, instinctively and instantly, when confronted with a situation which demands dispatch from both.

.

[Mick Strigg]

One of the demonstrations that we used to give students on the RN Gazelle course was an Nr Decay Demo. We would get the student to put his hand on the roof-mounted throttle lever and then stare at the Nr guage.

From 90kts and on a countdown of three, we would get the student to chop the throttle and the instructor would say "F*** me, the engine's failed!" and then lower the collective fully. In that short time, the Nr would have reached the red-line minima, so a flare would be required to regain the Nr.

The instructor would then complete a perfect EOL to a specified spot!

[Savoia]

.. the instructor would say "F*** me, the engine's failed!"

Ah yes, that sounds just like some former QHI's I know! ;)

[Fortyodd2]

Chris Scott,
Fair point. However, the "basics" in this instance are to get the lever down, control Nr and attitude. What happens next depends on a large number of type, altitude, speed, etc factors.
Apart from a fairly large application of rudder, I cannot image that the drills you would have used on the A320 suffering an engine failure at FL 300 & 500Kts would be the same as those in a Dakota on a half mile final.

[SASless]

The "Move the Cyclic Aft" concept works in certain situations, does not apply in others, is more important sometimes depending upon the type of aircraft being flown, and most importantly depends upon how quickly the Pilot responds to the Loss of Engine Power moving the rotor blades.

So as is so typical of "Cook Book" Piloting....anyone who clings to a singular approach or method to flying helicopters is just being flat assed stupid.....and in some circles....dangerously ignorant and arrogant.

The extreme display of the use of the "Move it Aft" concept is high speed, low level flight, where a fixed collective or even increased collective and an aggressive cyclic climb maneuver sets one up for a standard autorotation after a several hundred foot gain in height above the ground. The other end of the the spectrum is when doing an OGE Hover or very low forward speed autorotation....moving the Cyclic Aft isn't going to do a thing for you. The area in between the two is where there is so much room to be creative while entering the autorotation. How you manipulate the controls is directly dependent to the situation including whether you have a low inertia or high inertia rotor system. One benefits more from the Cyclic movement than does the other.


DB,

Is it they let the pitch attitude decrease or does the Sim demand an Aft movement on the Cyclic? What Airspeed was the failure initiated? How long did it take for the Pilot to respond?

I suggest you tell us more about the situation yourself.....as you were there it should be easy for you to do. What was the scenario....how were the Pilot's briefed....what were their backgrounds and experience....language differences?

More importantly....were any of them British Trained? How many had CAA ATPL's?

[Tandemrotor]

Fortyodd2
Apart from a fairly large application of rudder, I cannot image that the drills you would have used on the A320 suffering an engine failure at FL 300 & 500Kts would be the same as those in a Dakota on a half mile final.
For differing reasons, neither of those are likely to require a "large application of rudder" by the pilot.

For fixed wing pilots 'dipping in' to this conversation I will just reinforce where the similarities, and where the diffences lie.

In a fixed wing, airspeed is the thing that will keep you alive. Lack of it will kill you. In a helicopter, airspeed is usually considered largely irrelevant, it's Rotor RPM that keeps you alive.

Have a power disturbance in a FW and the pilots eyes are likely to be glued to the airspeed indicator (speed tape?) Have a power deficit in a RW and the pilot will be concentrating on rotor rpm above everything else. Even identifying a suitable forced landing site cannot override that.

[ShyTorque]

Tandem, well put.

Baston,

All those of us who were lucky enough to train doing real engine offs from all stages of flight were very lucky as the Queen did not worry about "£6 million" aircraft as the crews were and are more valuable. At the end of the day if you end up sitting in a field in your seat surrounded by a few tons of scrap aluminium - so be it - you have survived and can let the engineers worry from then on.

I'm 100% certain that the Queen did not allow her twin engined helicopters to be EOL'd to the ground. That was reserved for single engined aircraft only, at least since the 1970s when I was trained by the RAF. The reasons should be obvious.

The only time it was allowed on twin engined helicopters was for test pilots carrying out a trial. Even then, almost two decades after the aircraft came into service, during ideal and pre-planned circumstances over the very lengthy Boscombe Down runway, they managed to bend the one (Puma) they were allowed to EOL all the way to the ground. We (the OCU) had already come up with total engine failure/EOL drills and tail rotor malfunction drills in the simulator. At least one crew said after a tail rotor pitch spider failure over the sea that the training we provided saved their lives. Had they not been privy to it, the pilot said he would have possibly shut down the engines which was the incorrect thing to do in his case.

The most important thing on any helicopter to practice is the recognition and recovery from total power failure followed by a successful autorotation. Without that the chances of a successful landing are very poor indeed.

The chances of minor damage to an expensive helicopter on landing during an EOL are relatively high. Any minor damage would mean the job stops because we don't another aircraft in reserve, nor would the insurance companies allow us to train in that way.

Fixed wing jet pilots would throw up their hands in horror if it were suggested that they be required to carry out true engines off (deadstick) landings in the actual jet airframe for training purposes. Same thing.

So simulators are used, that's the whole point of them. However, beware of taking the handling responses to be as per the real helicopter in all extreme circumstances. What happens (i.e. what is programmed in the software) is based on a a "best guess" (off model) scenario because no-one has obtained real data from the aircraft, again for what should be obvious reasons.

[paco]

Savoia - having had three 206 engine failures, one at night with the Alton Towers L, that scenario seems very familiar! Two were compressor blades flying out of the side, and the night one turned out to be the NR gauge, but having set myself up and fired off a flare, I just carried on. Good job I did, because at the end of the field was a set of large tower lines which we discovered the next morning. No damage to anything aside from the initial cause.

I can confirm that the aircraft behaves very differently in the real world, and the denial factor is very relevant - i.e. "this isn't fair, all my engine offs have been over large green fields!" By the time you have sorted that out you are already on your way down, and if you are longlining you are likely on the ground. With twins, this is even more critical, as you have to watch the needles more to detect a failure in the first place, and the idea is to keep it flying, so dumping the pole is less on your mind. I did my 355 conversion before I did my 350, and it was very beneficial to do EOLs in a very similar type, but this is not the case for modern aircraft.

My first priority is to DUMP THE POLE because you don't want any drag from the blades, with maybe a slight check back in the hover or a bigger one at higher speeds. Some people have indicated that they would keep a high speed on - not sure that's a good idea, as if you are over the VNE for autorotation all you will do is go down faster as the driving area of the disk will go past the tip path plane, giving you less disk area to play with.



Phil

[SASless]

Shy,

My Uncle Sam drew no such distinction between singles and multi's....as i did EOL's in TH-55's, Huey's, and Chinooks. Granted, far fewer in the Chinook as EOL's were not seen to be as likely to be needed.

EOL's in civilian Helicopters are a subject that has many sides to it.

Insurance companies are all about limiting risks to their purse.

CEO's also look to maximizing the "Bottom Line".

That is why we do not do EOL's.

The next best thing is to do power recovery type EOL approaches to landing and hope that we get the Entry done right and control the descent and final stages prior to Touch Down in a proper manner.

If we arrive close to the ground in good shape, with bags of Rotor RPM, a proper pitch attitude and ground speed over a suitable site for landing.....then the odds are we shall survive the landing.

That applies to singles or twins.....and to Simulators as well.

We have to remember Simulators are not the same thing as real aircraft and can only fairly well duplicate the actual aircraft but not perfectly.

Sim's teach procedures and systems not aircraft handling per se.

[DOUBLE BOGEY]

BasTon and SAS,

If, during forward flight the engine(s) stops, my experience has been that we react only after the NR has decayed. The ONLY way to get it back is to flare. Lowering the lever in any helicopter will not bring the NR back,

Of course eventually the lever has to be lowered otherwise autorotative state will never be achieved.

I agree with you both. One size never fits all. However my post is about recovering lost NR, which lets be honest, is the most likely scenario in ANY total power loss event. If in the hover, in certain types, there is not a lot of hope. In others, as I explained in our 500 foot 206 throttle chop exercise, they fare much better.

However, training is about forming good habits, that will serve you well, when tired, things have gone wrong and you need a friend. This is the core relevance of Peters "Cyclic Back" approach and just maybe a feature in this accident.

NR responds to disc loading and that is what the cyclic flare does.

For the poster advocating the maintainable of "Attitude" .....well in effect that is a mild flare as the nose tries to drop. However, tired, in the dark, un expecting, it is likely you will need more than that. There is real value in Peters post and its about habit, once the power loss is recognised.

In a modern helicopter stinking along at 145 KIAS, very little speed needs to be traded for a significant gain in NR, this is utterly basic stuff BUT experience, time and time again shows that pilots simply do not react thus way. They know it, but they respond too late because it is not fully instinctive.

In the hover, I think we all adopt a more attentive attitude to a possible power loss. Especially at height. In Police Operations in UK this is substantially mitigated by the presence of the second engine. However, should we lose both engines in the hover our response has to be instantaneous as we do not have the most powerful tool for recovering our NR........AIRSPEED. Of course in the hover the lever has to dumped...fully....and completely....to the floor plate or its ENDEX. From this point onwards, lever fully down, it's a lottery based on remaining NR, height and control, and of course the characteristics of the individual type.

I think Peters post adds value to this subject more than most poster are inclined to believe. Airspeed is the most powerful energy store we may, or may not have at the point the engine(s) fail. The less we have, and the more decayed the rotor, the slimmer our chances of recovery. It's as simple as that.

DB

[soggyboxers]

I've never had an engine failure in a single, but I've had 3 double engine failures in twins. Luckily all of them were by day and I was not flying over built-up areas or particularly hostile terrain. All were in older aircraft with relatively low cruise speeds by today's standards (90 - 110 its). In 2 instances I was IMC at the time of engine failure. In all 3 cases I simultaneously applied enough aft cyclic to stop the nose from dropping and Nr from decaying and lowered the lever to enter autorotation. I don't seem to remember losing very much height at all during entry to auto and (once VMC) I was able to decide what sort of auto I wished to do to and was luckily enough to land the aircraft and myself undamaged.
For many years, and well before the days of simulators in which to practice these things, I was asked by students why I always insisted on doing autorotations when flying a twin as the possibility of a double engine failure was so remote as to to be discounted :roll eyes:.
In later years I often used to practice engine off landings (or touch-down autos as our trans-Atlantic brothers often call them) in a variety of twins such as the Bell 212 and the Twin Squirrel (as I found it little different from doing them in the single Squirrel :E).
I was lucky and have survived my career in aviation to beyond my best-before date so far despite my lack of co-ordination and skills (or so my basic rotary instructor always told me :}), but some days no matter how lucky or skilled the pilot he (or she) may just find that the grim reaper has just come calling.

[Shawn Coyle]

Sorry for being late into this discussion - been away doing FW sim data gathering.
For those who don't know Pete Gillies - he's an exceptionally experienced helicopter pilot and instructor, and his knowledge on autorotations is based on years of observation and experience. And a gentleman to boot.
He knows whereof he speaks.

[cattletruck]

T'was his first post too, I reckon it's no secret he'll get the hang of it soon.

[awblain]

These discussions of how to best deal with a loss of power are interesting.

I suggest the reason for what seem to be substantial differences of opinion simply reflect that helicopters are more complex than fixed wing aircraft.

In a fixed wing aircraft, you can trade speed for height, adjust attitude, alter power, and perhaps deploy devices to vary lift and drag (not all independent), and that's about all.

In a helicopter, there's an additional energy store in the rotor to take into account, and a wider range of relative wind values can be experienced, vertically and in azimuth. The lift/drag on the rotor can be changed quickly, with attitude changing in response. There's a significant gyroscopic effect too, restricting acceleration and attitude.

With a three-ton helicopter, the kinetic energy in a 10-m diameter, 200-kg rotor at 200rpm (~2MJ), scales with rpm-squared and matches the kinetic energy for a forward speed v~75 knots and the potential energy gained from dropping h~200 feet. The important energy quantities involved in this case are all comparable in size, and the best way to trade them can clearly be debated.

A very plausible answer seems to require "it depends". The importance of maintaining a store of energy in the rotor is clear, but there are different ways to achieve that: exchanging height, forward speed, or by reducing rotor drag.

[FC80]

I've never had an engine failure in a single, but I've had 3 engine failures in twins.

Am I missing something here or have you mixed that up?

[JimEli]

Shawn +1

I'm a much better pilot for having flown with Pete at his school.

[Savoia]

Having had three 206 engine failures, one at night with the Alton Towers L, that scenario seems very familiar! Two were compressor blades flying out of the side, and the night one turned out to be the NR gauge, but having set myself up and fired off a flare, I just carried on. Good job I did, because at the end of the field was a set of large tower lines which we discovered the next morning. No damage to anything aside from the initial cause.



Good God Phil, that is more than anyone should have to contend with! And all three in the 'safe as houses' 'Jetbox'! Bravo however, on getting down safe and sound, you have my unrestrained respect. Those rotorbursts .. they weren't by any chance on aircraft which had been used in repetitive lifting-work were they?

For those unfamiliar with the Towers operation, John Broome (the original developer of Alton Towers) was pretty much a workaholic and in the winter months there was little hope of arriving back at Tilston Hall (John's residence) before dark. The Colonel had the Schermuly flares fitted to the craft and had begun discussing the need to upgrade the operation to a twin. Eventually a Bell 222 was bought but this was some years after the Colonel's departure.

I had always wanted to fire-off one of those flares but .. the Colonel would have none of it. Was it of help during your forced landing? Have never seen one in operation.

Soggy: Bravo amico! Presumably you were flying those 'early twins' with insufficient power to remain aloft? ;) Ah yes the TwinEcureuil, in a practice (throttles to idle) engine-off landing. Especially with high skid gear. One must be on ones toes!

[BOAC]

My memories of auto-rotating a Whirlwind on the short pre-Harrier course at Shawbury have well faded, so could someone (patiently) explain the aerodynamics whereby it has been said that a stalled rotor disc could bring itself to a standstill? Surely even stalled there is still a rotational force on the blades which would keep the disc turning if air is passing through the disc (ie heli falling)? AAIB were, it seems, presumably deliberate in stating that neither main or tail rotors were rotating at impact, which is a concept I find hard to grasp.

[HeliComparator]

Normal autorotation, lift vector is inclined slightly forward (relative to the blade) so it pulls the rotors round and has enough oomph to overcome the gearbox frictional losses, oil & hydraulic pumps, tail rotor drive etc. this all despite a significant positive pitch remaining on the blades with the lever fully down.

If the angle of attack (being dependant on the blade pitch angle, vertical speed and the forward speed ie rpm) exceeds the critical value, then the blade stalls. Now the lift vector is much smaller but also inclined well aft (relative to the blade), so as to drag the blades and make them slow rapidly. The increased rate of descent increases the angle of attack, as does the slowing. Unlike a FW you can't just pitch the nose down to recover because the blades are pointing in all directions.

[Savoia]

My memories of auto-rotating a Whirlwind on the short pre-Harrier course at Shawbury have well faded, so could someone (patiently) explain the aerodynamics whereby it has been said that a stalled rotor disc could bring itself to a standstill? Surely even stalled there is still a rotational force on the blades which would keep the disc turning if air is passing through the disc (ie heli falling)? AAIB were, it seems, presumably deliberate in stating that neither main or tail rotors were rotating at impact, which is a concept I find hard to grasp.

Cue Bastiano with his memories of Whirlwind autos!

In the meantime .. take a look at this, from 18:50 onwards:

M5i2XRweAvE

Hopefully someone will pipe-up with an aerodynamics explanation of the physiscs behind why, if you allow Nr to decay too far below the bottom of the green, it becomes unrecoverable.

Not that this applies to modern craft but .. in some of the early helicopter prototypes the blades actually 'snapped-off' when the Nr decay became excessive.

As far as my awareness of 'modern' craft is concerned, what I understand is that the 'driving' portion of the blade used in autorotation is simply incapable of recovering the lost inertia of a 'stalled' or sufficiently slowed rotor and, even it it were, the airflow over the blades would have to be 'just so' in order to get them rotating again and which positioning of the airframe relative to the desired airflow would be impossible to control in a 'free-falling' aircraft.

[Arkroyal]

Apologies TC, just one more.

Indeed Bast0n, I remember well my one and only complete EOL in a Wessex 5 when you heaved both speed selects on me.

Not sure the Queen agreed with your methods though :O

[Thomas coupling]

Now we are getting somewhere with excellent posts from Savoia and Paco. Other very experienced helo drivers are also in agreement with the statement:

At an EOL entry gate, the mantra should be to lower collective first to prevent Nr from decaying further and adjust cyclic second to maintain attitude.
If this tactic became second nature, it would serve you well, time and time again.
NOW: A more experienced pilot (and I'm sure most pilots think they are more experienced :ugh:) will have either been taught or at least shown the spectrum of entry gates so that they will have covered nearly all eventualities.
And this means engine(s) failure from 50 feet/high speed right across to a high hover. The former will demand that the collective should be lowered at the same time as the cyclic selected aft. The hover will demand collective ONLY and NO cyclic aft whatsoever. So we have a sliding scale of cyclic position ARE WE ALL AGREED? the message I am making is that Mr Gillies or whatever - shouldn't go around preaching to the NON converted (ab initio's) that AFT CYCLIC first - is the way to go. Because here, he is categorically and utterly wrong. He is also wrong when he believes that this is the best kept secret (what is all that bollox all about?????).

I have been privileged in my early training to have been taught by the finest military Instructors in the UK. (Tri Service)CAT A1 Instructors. I went on to become an A2 Instructor and flew single engine a/c for many thousands of hours. I have carried out several hundred EOL's to the deck. I have even carried out EOL's in Sea Kings before that evolution was deemed too expensive by HM!! I know what it is like to 'lose' an engine in every conceivable configuration known to man:*
And I know (a) There are no secret's in aviation - people have died discovering them all. (b) ALL EOL's without exception require the pilot to THINK collective first and cyclic second. The choice after that is yours based on the flight mode you are in.

[G0ULI]

When a wing (or rotor) stalls, the airflow becomes very turbulent and the net result is pure drag with no lift at all. The rotor (or wing) is effectively at right angles yo the direction of airflow. You need to be able to reduce the angle of the airflow across the wing or rotor to enable it to function as a lifting device again and for that you need engine power to overcome the drag.

[Savoia]

TC: I am in support of your view. (See also the H-19 video above for the 'old school' and proven [for those aircraft at that time] autorotational teaching method).

However, I am sympathetic to HC's perspective in that (I think) we may (to some extent) be talking 'autorotational semantics' in that even among us 'collective first' types .. there is (or so I believe) a recognition that cyclic control is 'intuitive' and which may translate into simultaneous or even 'cyclic first' responses according to the specific profile of the craft's entry into autorotation .. if indeed that makes sense.

One thing is certain (as several have pointed-out) and it is that there are certain scenarios in which one would decidedly not apply aft cyclic first. The same however cannot be said with regard to pitch.

[paco]

Savoia - the rotorbursts were purely down to bad maintenance - the one I managed to get on to a small island in some Loch or other on the Fort William run hadn't been comp-washed for a couple of years. The other one over Manchester airport (Kilroe's) was also bad maintenance, but there was a lot else wrong with that aircraft as well - I believe Dollar charged over £30K to put everything right after the ambulance conversion that was done in Blackpool. You can imagine that I took an early interest in what engineers were doing (or not doing) to my machines!

Actually, the flares were helpful - you need to punch the first one off inside the first 1000 feet, then the second around 400 because they take time to deploy. They stopped using them on the Gazelles in the Army because they would occasionally fire off when you pushed the transmit button - Eurocopter electrics again! :)

I've taught hover autos from 50 - 100 feet (powerlines) in the 206*, and you do need a slight check back on the cyclic in those cases otherwise the beast will gain speed all by itself, when you really should be doing a vertical** - to this day, even at the top of the avoid curve, I would probably do a vertical rather than try to gain speed, flare, etc.

*Don't try this at home without proper supervision! :) Especially not in anything that's not a 206 (big blades, robust construction). Naturally, the collective going down takes priority.

**In the same vein, if you try to take off vertically, but do nothing with the cyclic, you will find the machine gaining some airspeed high up by itself - you need a check back in that situation as well.

WRT your earlier comment, the driving portion of the disc has a lot to do, and it only really covers about a third of the swept area. It's easy to see why, if the blade RPM gets too low that it has more work to do with less ability. In point of fact, the driving area is really windmilling, because it is driving the tail rotor and other hangers on. The only parts that are truly in autorotation in the proper sense of the word (zero torque) are the neutral points between the driven, driving and stalled areas.

Phil

[170']

I think most people are in denial about the levels of training that the collective ‘we’ enjoy!

I’ve had my share of ‘emergencies’ With the last adventure being a power rollback to idle (low side Gov) a couple of years ago in a heavy helicopter just as about to drop water in a tight valley and nowhere to go but up. The engine didn’t shut down but nor did it come back. When I listened to the CVR; I wondered who the two guys were, because it didn’t sound like me and my partner in crime.

Not one of my emergencies ever went according to the book, training or planning. But more on a slender touch of those things; and a large dose of divine providence.

It all happens so quickly that regardless of how well trained you might think you are? If you can’t train much more than operators currently allow?
You fall into the basket with the rest of us. Consistently lacking in ‘emergency training’ currency.

But I’m sure the accident pilot had his measure of training as per current regulations and I have no axe to grind there!

I’m neither an ace nor a sandbag. Just a consistent working pilot who has operated often in difficult conditions in many places around the world; and having flown multi crew with many nationalities, each with different basic training standards and cultural affect. These issues make little difference in the long game, Yank, Brit or Iranian. If we sat there poised waiting for the emergency we’d all need a shrink on a twice monthly basis from the stress alone?

We all try to prepare for when something bad happens, but we can’t maintain the effort for very long out of a 14 hour duty day and 8-10 hours flying.

What’s an insane/dangerous operation in the view of a charter pilot used to flying from an airfield to a big private house in the country; is daily bread and butter for a guy working a 205 or a B3 in Canada or wherever. Crap weather for me in a 212 slinging drills, is nothing for a guy in Port Harcourt during a strong Harmattan.

Look at the comments re: the guy slinging xmas trees with a 206 recently. My feeling when I saw it was of a a high time guy with good hands and feet.
I Just thought he was doing a great job considering it was a 206… I used to do it with a 500 and a Lama back in the day and declined to do it in a 206! Because I’m always scared of mast bumping when I get carried away, and you do get carried away, its great fun and one of the reasons we do it! It only seats one when slinging and it’s a fun job. Others took a more critical view.

No one’s objectively right or wrong! And many are swayed by the nanny states in which many people have been raised and then thrive in, perpetually rambling on about ultimate safety in helicopters. It’s always a brownie point if you call safety, even when talking out your ass!

Based on $$$ - not common sense, the industry thinks a trip to a sim or a line check or OPC every six months makes you current on emergencies…Bull****! We need to practice far more frequently than that but the game isn’t played that way unfortunately. We all live in a state of denial when it comes to our capabilities. If you don’t believe me, ask for a shaft failure with sound effects at TDP+5 + 5 next time you’re in the sim and see what happens. 9 out of 10 times you’ll screw up the first one or two; the big problem being that in real life there’s no do-overs!

I have no idea what happened in Glasgow and can’t begin to speculate. But at night low level in a turn! Anyone who could get away with an unexpected double flame out as an example, has more than most of us can muster…Sometimes an accident is just an accident and there’s nothing to say that the pilot was playing the game in any other way than the way he’d been trained and had approval for.

The drift into auto technique is shameful to read. How a bunch of people claiming to be seasoned pilots can think there’s a ‘one cure fits all’ - is one of the reasons I avoid whenever possible riding in the back of a helicopter.

I think that Proon should open a ‘closed posting’ section where you have to prove you’re actually an experienced helicopter pilot before you can post, as I’m sure some of the posters are imposters or inflating their experience beyond all reason. Many comments make no sense coming from seasoned pilots.

TC . I generally disagree with you as a principle of life, but I support you 100% in your comments here.

A note for any family or friends reading this forum.
I offer my sincere condolences and I’m very sorry for your loss! I didn’t know David and can’t think of a single thing to say that would ease your suffering. But he was in a bad situation and he did the best he could, maybe the best anyone could? …Sometimes the deck is stacked against you.
RIP David!

[Shawn Coyle]

A couple more points - Pete backs up his advice with examples (mostly H500's if memory serves me right) where, following an engine failure the pilot(s) elected to dive towards the ground (pushing forward on cyclic) at the expense of rotor RPM. All of the examples showed very heavy landings on the left side of the machine due to lack of control due to low rotor RPM.

Having done quite a few HV demos in OH-58/Bell 206 to budding experimental test pilots, I can attest that in the high hover case, it's necessary to maintain a level attitude following the failure - mostly with a small amount of aft cyclic.

I remember hearing that during the HV tests for one of the Bell teetering rotor helicopters that the test pilot pushed forward on the cyclic when the (very) high hover point was first tested - his comment after several minutes of silence following the nearly vertical nose-down attitude that was observed was something to the effect of 'Don't push forward'.

On the other hand, don't be slavish - one US military helicopter training school used to insist on aft cyclic in a low altitude hovering engine failure when it wasn't needed.

Something else to remember is that real engine failures are not like the training ones- every single pilot I've talked to who has had a real engine failure in a single engine helo has commented on the very large surprise factor compared to training autorotations.

[DOUBLE BOGEY]

170' - great post!! The ending made me feel sad and slightly ashamed that I had really forgotten what this thread was all about.

DB

[SASless]

Very well said 170".:ok:


Shawn.....the "Surprise Factor" applies to Multi-Engined helicopters too especially if in other than Normal Operations that keep you light enough to fly around on one engine.

Load the Bird up doing Vertical Reference work in steep terrain sometimes as 170 mentioned where the only way out is UP.....and sometimes flight path restriction comes in the form of a raging Forest Fire.

All engine failures are not the same....it is one thing for the fire to go out....and another for it to go outside when a Power Turbine Wheel explodes and sends shrapnel all over the place.

Failures certainly are rarely straight out of the Check List or Ops Manual....and that is why it is hard to "train" for every eventuality.

When things go wrong....you do the best you can.

I once handled a Cockpit Hydraulic Fluid fed Fire, Utility Hydraulics Failure, and a loss of a tail rotor control pedal (physically lost the pedal from under my foot) while IMC with a Sling Load in Mountainous terrain.

The Checklist and prior Emergency Procedures Training did not cover that situation with much detail if any.

We did not look at the Checklist or actually conduct a single drill as laid out in the Manuals and SOP's.....but we handled the problems and recovered the aircraft to a safe landing zone.

Past Training helped structure our actions but being able to think our way through what we needed to deal with and set the right priority to it was the key.

That holds to performing an EOL or recovering from a single engine failure in a Twin.....you have to apply the right technique for the conditions you find yourself confronted with. There are some systems failures that demand nearly instantaneous reaction from the Pilot.....and certainly an engine failure on a Single Engine Helicopter is at the top of the list....as if Rotor RPM is lost then nothing good will happen after that.

[DOUBLE BOGEY]

To lighten the mood somewhat....the worst thing that has happened to me in a helicopter is ****ting my suit on the first leg of a double Brae. The worst thing I have done in a helicopter is complete those double Braes......without breaking the neck seal!!

DB

[500guy]

I think the point Pete was trying to make is regardless of how much you "know" your brain is not yet engaged in the 1-2 seconds it takes to arrest the rotor RPM decay at high speeds.

To respond to a stimulus it must be detected by the senses, processed through the cerebral cortex, verified, and then muscles must move to respond, then the aircraft itself must respond. This whole process takes 4.6-5.0 seconds as confirmed by numerous tests in many countries including the UK. I may be able to dig them up if anyone is interested; they were cited in a Wirestike lawsuit I was involved in. The only reason pilots are able respond quickly enough with control inputs in a real sudden engine failure is exactly because they DO NOT use their brain, not the cerebral cortex anyway. A reaction can occur in just a fraction of a second, butr eactions must be conditioned, contingent.

If you teach as PG advised to make the aft cyclic part of your reaction then you can survive high speed engine failures. True, that on some engine failures below vy, it might be un-needed, or it’s possible it could even prevent you from getting to a better spot because you have slowed yourself to much.

The alternative however is to teach as TC suggested, to lower the collective and consider your spot which is going to take 4.6-5 seconds and in some highspeed engine failures that are truly surprises, time might not be sufficient to do that.

Pete has been teaching autorotations to experieced pilots for 35 years. He is one of the most highly respected instructors in the us, he is not over inflating his esperience.

Like many of you I agree, that it isn't that pilots do not know that at high speeds aft cyclic is required. If asked in a classroom they will all tell you that. What Pete's point is they dont do it when they need to because it has not been trained to be a reaction and he sees it person, likely daily.

I learned down and aft simultaneously, and then consider your spot and I believe that is the way to go.

(Edited to add the last paragraphs)

[SASless]

The worst thing I have done in a helicopter is complete those double Braes......without breaking the neck seal!!



Errrrrr.....ahhhhhhh.....don't you mean the "Second Worst Thing"....as I believe breaking that Neck Seal would have been far worse than not.:uhoh:

[soggyboxers]

FC80,
Sorry, age and a long day with the hot African sun burning my pink shiny helipad, combined with your surprised reaction, caused me to look at my last post and correct it - what I meant to say was that I never had an engine failure in a single, but I've had 3 double engine failures in twins :O. I was always taught that in forward flight I should simultaneously lower the collective with a touch of aft cyclic to prevent the nose dropping and use the flare effect to preserve Nr and prevent too much altitude loss, giving a few microseconds more to try and figure out how to get the beast down without killing myself. I guess it worked out for me because I survived and I always told my few students that watching their efforts at energy management helped me to learn that there are many ways to skin a cat. I had a few interesting single engine failures in twins which actually involved more problem solving and delicacy of control input than was ever the case with my own experiences of double engine failures. Anyway, what do I know, as I'm now reduced to reading what real aviators do :}

[Devil 49]

Autos are energy management; you have three lots of energy (height, airspeed and Nr) to manipulate and arrive safely on the ground. How you manage that is dependent on many factors and there is no initial reaction that fits all of the possible entry scenarios.

Dogmatic posts such as the OP don't seem to have grasped that reality.

Exactly right (spot on?) regarding energy management. But I am more than a little sympathetic to the OP's point regarding autorotational training regarding disk loading and energy transfer in the autorotation entry which if I may- is the primary point attempted to be made- not airspeed, a separate energy variable that certainly has to be considered.

A sudden and complete power interruption at twice Vx/Vy is a very different experience than most training exercises and is complicated by surprise and shock, especially in twin-tin, as SASless points out. I am constantly shocked to hear otherwise competent pilots excuse poor decisions because "they have two engines". Double engine failures do occur, not to mention drive train and antitorque failures.

[FC80]

FC80,
Sorry, age and a long day with the hot African sun burning my pink shiny helipad, combined with your surprised reaction, caused me to look at my last post and correct it - what I meant to say was that I never had an engine failure in a single, but I've had 3 double engine failures in twins http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/embarass.gif. I was always taught that in forward flight I should simultaneously lower the collective with a touch of aft cyclic to prevent the nose dropping and use the flare effect to preserve Nr and prevent too much altitude loss, giving a few microseconds more to try and figure out how to get the beast down without killing myself. I guess it worked out for me because I survived and I always told my few students that watching their efforts at energy management helped me to learn that there are many ways to skin a cat. I had a few interesting single engine failures in twins which actually involved more problem solving and delicacy of control input than was ever the case with my own experiences of double engine failures. Anyway, what do I know, as I'm now reduced to reading what real aviators do http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/badteeth.gif

I was going to say - if you went into autorotation every time you had a single engine failure in a twin, you were missing a trick, old chap! :8

Anyway, the fact you're still here after a string of incidents like that surely attests to the fact you know what you're talking about!

DB - lucky you had one of the old style suits and not one of those fancy new ones with one-way valves under the epaulettes! :ooh:

[Thomas coupling]

170: Careful now...you're getting soft. Personalities aside - even some of the hardened crims in here are agreeing to what you and I profess. It makes sense, that's why. Hopefully the message is now delivered and you can go back to sticking pins in my effigy :E

DB: In case you didn't notice this thread has absolutely nothing to do with the Glasgow crash which is why the majority decided to split it off.
So no need for the sympathy vote bucco. :yuk: PS, I am sure 170 will lend you some hat pins too :E

[nigelh]

I've been thinking about it and personally I don't think I have ever entered an auto without needing to pull back on cyclic . Also I was taught that as one tends to fly quite a lot with your hand away from collective it makes sense to start a flare immediately ( also my early flying was crop spraying where you certainly do not want to drop collective first !!!)...just because your hand is already there and it will buy you precious seconds of extra time in which to drop collective . As for which should happen first in a perfect world .... I'm not sure it really matters . If you keep the rrpm in , or just above the green it works for me .

[G0ULI]

Funfly
The windmilling blades would be in the same plane of rotation as the powered rotor, so they would be affected by the same aerodynamic forces and stall at the same time.

There were experiments with ballistic parachutes as a recovery mechanism, but explosive bolts in the rotor head and large lumps of rotor blade falling away from the helicopter when the system was activated discouraged further trials.

[alouette3]

I learned my helicopter aerodynamics by reading the section in the AP3456.In that venerable document (Thank You, the UK MoD) the section on autorotation has the phrase "apply aft cyclic to restore Rrpm" Drummed into me since I was a baby pilot. Case closed and no big secret ,as far as I have been concerned.
The second thing I learned and have applied all my life while flying twins and singles is "linger not in the curve of the dead man ,lest the earth rise up to smite thee". I know there are good, well-paying helo jobs out there that require a high hover,but, for the rest of us, that would be a good rule to follow.
Finally, an instructor once made the comment that a good autorotation is judged by the entry not by the ending.He went on to explain that you can be over a football (or soccer) field or over an airport,but, if you screw up the entry after an engine failure, you will still end up dead.The other side of that coin is that you can be over a confined area and yet if you do everything right you will survive.Cuts and bruises and broken bones and a badly bent helicopter,but alive. Fair points,don't you think?
Alt3.

[funfly]

Gouli,
Thanks for your reply to my question, on reflection I am surprised that you have not given me the reply I deserved for what was, on reflection, a fairly stupid idea. (and one that my embarrassment has required that I deleted!)

I think the question I was really asking is that there may be some way of offering additional security to rotary aircraft that operate low and in the vicinity of crowded areas even if this was at a cost to performance. I appreciate that it would generally be too low for a ballistic parachute to be practical.

I remember when ballistic chutes were first considered for fixed wing the general reaction was not positive for a number of reasons. Nowadays, however, they are accepted and the pilots using them no longer considered 'cissies'.

[G0ULI]

Funfly
As a fixed wing pilot of very limited experience but a lot of theoretical knowledge, I have found this forum to be most informative about helicopter operation and hazards. Perhaps it would be technically possible to design a rotor head that would allow the blades to be angled sufficiently to unstall a stalled rotor disk given sufficient height. I don't think it would have helped in this particular incident. Perhaps a 'one shot' system with a small rocket fitted at the tip of each rotor could be used to bring a stalled main rotor back up to speed? The system need not be complex or heavy and the added rotor inertia could be advantageous. Not sure that health and safety would approve.

[DOUBLE BOGEY]

TC - why do you always assume the role of self-elected thread policeman. Even when you are not talking technical bollocks you still manage to irritate me.

Actually, I guess on reflection this thread belongs to you seeing as it was your utter dismissal of Peters very competant post that generated this in depth discussion on Autorotations.

Now I am going to assume that you clearly know how to enter auto, in all stages of flight. Your subsequent postings demonstrate that.

However, had you given a little more thought to Peters post I think you would agree that the only practical and available method to restore a seriously decayed NR is to extract the energy from airspeed using the flare.

A flare is not an option at low speed/hover. This is precisely the point Peter is trying to make!! Now, just for once, read my post twice before you react, as you usually do, with arrogance personified!!

DB

[Savoia]

Goolie's rotor-tipped in-flight-autorotaion-restart-system:

iVCFWwYaZ6c

[4Greens]

As a former fixed wing pilot, my real worry is a bunch of helo pilots arguing about how to fly a helo after an ehgine failure.

[Savoia]

Been done.



Quite so.

Indeed since the days of the Catherine Wheel!

[awblain]

Vertical speed and horizontal speed each have v-squared energy terms.
Rotor speed has an rpm-squared energy term, and a drag/work-done-moving-air v-squared dissipation term. Potential energy has a height dependence.

These components of energy all have to sum to zero at the end of the process, and the key goal is low vertical speed at zero height.

Having lots of energy dissipated in drag from the rotor is good, but there's only one solution to the energy sum with horizontal and vertical speed both zero on touchdown. That might not be achievable.

The potential energy in a 200 feet drop is about equal to the kinetic energies of a 70 knot speed and a ~200rpm rotor speed. There's also the initial groundspeed, and the energy lost beating up the air to be considered.

[Dick Sanford]

Firstly, may I add to the many messages of condolence to the families of the people on the ground, the helicopter flight crew, and the Police Force involved.

We have the best people in the World investigating the accident; the AAIB. Please let them do their job.

I had the pleasure of meeting Pete and his lovely wife in October this year.
Pete may be new to PPrune but he is most certainly not new to flying helicopters; he would most likely put a reasonable number of you 'experts' to shame, a true professional.

Pete (and he will correct me if I am mistaken) is referring to the use of available stored energy that the pilot can call upon to prevent Low RPM Rotor Stall should they find themselves in a situation where their single engine has failed.

Cruise Flight:
With a low inertia rotor system, the least amount of energy stored in the helicopter and which is immediately available to the pilot, is that stored in the main rotor (kinetic). Hence the rotor RPM decays quickly.
However, the most amount of stored energy available is stored in the forward airspeed and this is available to the pilot instantly. The pilot can call on this energy to prevent rotor rpm decay during the entry into autorotation by applying aft cyclic.
In fact if I take an R22 at a 90kt IAS cruise flight condition I have some 8 seconds of stored kinetic energy that would allow me plenty of time to lower the collective (Note: it does not change the intervention time). It is there…. so use it.
For those that say 'well I might need it for range' then range is of no use to you if you are a brick! The primary task is to establish autorotation. If you fly defensively you will reduce the requirement for range autos (I am talking single engine operation).

In the hover the pilot should lower the collective lever and allow the helicopter to descend and regain the RRPM before applying fwd cyclic for airspeed; the positive effect of increasing the airspeed is an increase in RRPM.
However there is a negative first, and that is a reduction of RRPM. So if the pilot should apply fwd cyclic before the RRPM has recovered this will add to their problems.

There is more but I am due out to dinner.

R

[xlsky]

one might end up in IMC conditions at some important part of the rocket assisted autorotation? perhaps better with compressed air..

[awblain]

I think the answer is - it depends.

Can your helicopter descend vertically without power at a steady speed?
Is that speed slow enough that it can be exchanged for rotor speed by increasing collective pitch just before touchdown?

If not - higher weight? smaller rotor? - then some forward speed is inevitable, to give more lift at lower collective pitch, so that the vertical speed is slow enough that it can be pulled away on touchdown.

In the video it looks like - from those heights/speeds and in that helicopter - forward speed is required. It never looks like a stable state of descent is reached in the time available (although the ground is out of shot), and so there's a juggling of rotor speed, forward and vertical speed throughout the descent.

A lot of relevant issues seem to be be raised in the text with
Height?velocity diagram - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Height–velocity_diagram)

In steady vertical descent at speed v_d, potential energy is being exchanged for kinetic energy of the air beaten down through the rotor disk at v_f, and a little into turbulent motion too. From energy conservation M.g.v_d ~ A.rho.v_f.v_f.v_f/2, and from momentum/Newton-II M.g ~ A.rho.v_f.v_f. This gives v_f scaling with the square root of M/(A.rho), making it easier in dense air, with low weight and a big rotor, and gives a simplistic vertical speed of v_d ~ v_f/2. That's not comfortably distant from a vortex ring state - as v_f ~ v_d, rather than v_f >> v_d.

For the R44, A~75 sq-m, M~1000kg, so v_f ~ 10 m/s, v_d~5 m/s: I'd say that 5 m/s makes sense from the video.

[SASless]

Watching the video of the R22 doing HOGE autorotations reminds me of Shooting Craps with Loaded Dice.....it works so long as the Dice are your own and you know what numbers they will show when rolled.

As we have pointed out in the past....knowing the engine is going to quit and being prepared for it does not happen in the real World.

I wonder....what would the Video look like if you added in a mere 1.0 Second delay to the Pilot moving any controls? Better yet add a 2.0 second delay which would still be a pretty quick response by a Pilot who experiences an engine failure for real.....reckon the end would be as pretty?

Ask Nick Lappos, Shawn Coyle, and John Dixson about that.....as they have all done it in their Test Work.

[chopjock]

SAS
I wonder....what would the Video look like if you added in a mere 1.0 Second delay to the Pilot moving any controls? Better yet add a 2.0 second delay which would still be a pretty quick response by a Pilot who experiences an engine failure for real.....

But any pilot HOGE would be primed and waiting for that yaw and change in engine noise. Unlikely just freezing on the controls...

[[email protected]]

Unless your job involves long periods of OGE hovering when you are usually concentrating on performing a task or mission.

There is no ONE way of entering autorotation that will optimise your chances in every given situation but the basic idea that lowering the collective fully WILL prevent any further Nr decay and flaring with the cyclic WILL (if you have any forward speed) help recover the Nr - is what we should be highlighting to all and sundry, especially the low timers.

One exception maybe - the Germans used to teach, on the Huey at nap of the earth flying heights, to raise the lever first to get the tail clear of the ground before flaring so you didn't add a tail rotor strike to your list of woes. But of course the Huey had massive rotor inertia - try that in a Robbie and it would go very wrong very quickly;);)

[Lonewolf_50]

The aft cyclic also loads the head a bit in opposition to the unload that lowering the collective may induce, depending upon rate of control movement. HC raised that point early on in this discussion, and given how rotor blades get their autorotational qualities, his early point on "don't unload the head!" remains sound advice ... and is consistent with various posts on energy management, Nr maintenance, and control manipulation.

I guess Pete has seen this as an instructor, but Savoia talks to what I have observed. Lowering the collective does not/should not happen in isolation. When flying a helicopter, one typically has to move the cyclic (and pedals) in compensation when the collective is moved depending upon the maneuver and probably on the amount of automatic/stabilization features that a given helicopter has, and has on at the time. For example, if you have an "altitude hold" feature engaged when the engines quit, you either have to override is with force or disengage it while lowering the collective and adjusting attitude at the same time.

Without a bit of practice at that, the reaction won't be instinctive, and one could indeed get a bit behind the aircraft. The Real Life experiences shared in the last few pages are most instructive, and I thank the gentlemen for taking the time to share with us their actual experiences. The only engine failures or rollback I ever had were on two engined machines, so a precautionary landing was done: hooray for two engines! :ok:

I am not sure why Pete made the case about a deep dark secret. What he may be reflecting is what he's seen people actually do, which means, he may be pointing out what reflexes and instincts seem to happen in aircraft, rather than what someone may or may not have been taught.

From the Australian teaching manual: LEARNING OUTCOMES:
The student will be able to follow the PFL drill and satisfactorily enter autorotation, glide towards a selected area, make a distress call and secure the aircraft for a landing. For the practice situation, the student will be able to overshoot safely by 500ft AGL.
An unpowered helicopter does not so much glide as plummet. :E
(With a nod to Monty Python and the flying sheep sketch :hmm:)

[SASless]

But any pilot HOGE would be primed and waiting for that yaw and change in engine noise. Unlikely just freezing on the controls...

Done any long lining....Forest Fire fighting....fertilizing with a bucket....fish hauling....construction work.....Cherry Drying?

Pilots do not go about their business day after day....hour after hour....sat up on their seat with their mind alert and focused upon responding to an engine failure....that just doesn't happen unless something alerts them to a problem beforehand.

You focus your attention on the immediate tasks at hand and hopefully your training and experience is such that you react properly when the time comes and you do so in a very timely manner which requires that initial response to be instinctual and correct for the situation.


Crab,

The US Army did the same as the Germans on that.....as when flying very close to the Surface at or above 90 Knots....you did have to "Pop" the Collective first....then apply a large amount of Aft Cyclic to Climb to about 300 feet before reaching 60 Knots and initiating a "normal" autorotation.

Yes....the old Huey has lots of Inertia in the Rotor system....which has saved a lot of lives over the years. The transition to the Huey from Low Inertia Rotor Systems takes some understanding and acceptance, in the past I have found some reluctance to that when doing Conversion training.

Usually it takes doing a Hovering Autorotation....landing to the ground....then picking the aircraft up and repeating the maneuver while turning the aircraft 180 degrees without using any throttle, to get the point across.

Don't be trying that with your Gazelle.

[[email protected]]

My point entirely SAS;)

Personally I have always taught a co-ordinated entry to auto such that the rate of lever lowering or the rate of application of aft cyclic are variables based on the situation. The only real exception is the high hover although, as has been said before, the nose will drop as the lever is lowered so some aft cyclic will be required unless you want to gain airspeed.

[170']

Chop Jock

Someone who doesn't fly much OGE hovering might be primed I agree,and they should be! But by far; most slingloads percentage wise are performed by people who do it all day everyday and it becomes just a standard flight regime.When I'm assembling something with a 150-200 foot line, I'm mostly focused on not screwing up and hurting someone on the ground/tower or whatever. That and not looking like a schmuck if I do screw up!
The actual flying is just automatic.

In my experience and speaking only for myself. I do not respond in 1.6 seconds (I read somewhere I should) It takes me longer than that to think
F*** what is it now!

As I said earlier, it's impossible to stay primed and ready for immediate action all day long (very long days in utility work). It's such a normal procedure you can compare it to taking off from a runway for an airplane. yes a degree of alertness is always there, but fatigue and sometimes boredom take their toll.
We as a species are just unable to function in a constant state of super heightened alert.

Just an opinion, with no math or stats to back it up ;-)

[SASless]

Takes us back to a discussion about Mode White, Green, Yellow, and Red Modes of Piloting!

The transition from each is pretty quick....but to jump a Mode does not go quickly or well and to jump two Modes scares the Bejeesus out you.

Pilots should stay in the Green Mode....and never the White! Occasional visits to the Yellow Mode are normal, expected, and consistent with good Piloting.

Forays into the Red Mode suggest unexpected mechanical problems with the aircraft or sudden abnormal events occurring from outside sources not under the Pilot's control or having been caught smack dab in the middle of a White Mode Experience.

The White Mode is that warm, fuzzy, feel good, thinking about Dinner, cuddling with your Girl Friend before going home for Dinner with the Wife sort of mental state....where you are miles away from where you are sitting.

The Green Mode is you are paying attention to what is going on....are attuned to the situation so you are anticipating any actions you might have to take, still relaxed and comfortable.

The Yellow Mode is when you tweak to the need to pay attention to a specific issue that may require distinct action in either maneuvering the aircraft or taking some unique action to correct a problem or situation.

The Red Mode is triggered by something that grabs our attention which unattended to will result in much worse things happening. That is when the Adrenalin flows...the Heart Beat turns into a Snare Drum Tattoo....and your focus turns to exactly what is the threat.

[170']

Exactly..Couldn't find the succinct words...Well done lad! :D

[NickLappos]

Some general thoughts on the topic of recovery from OGE Hover engine failure:

1) The Dead Man's Curve is a decent guide to how much trouble you are in. If below 250 to 300 feet AGL when the engine quits at a hover, you WILL crash. The operative issue is the stored energy in the rotor (high for a Bell, low for a Robbie), and the quickness of the pilot in getting the collective down.
2) The maneuver from low altitude is hardly an autorotation, it is more related to a controlled drop and a race to gain enough forward speed to help create a cyclic flare at the bottom. The trick is to fall while gaining forward speed by lowering the nose sharply (25 degrees, which is like pointing at the ground). Lower the lever a bunch and try to keep the rotor in the green. As the earth looms up, sharply pull the nose up to flare, and pull the collective to your armpits to use all the rotor energy left to cushion the blow.
3) If you are at 500 feet AGL or more, the forward speed you gain will be enough to get you to normal autorotation speed, so bottom of the maneuver will look like a normal autorotation, and the success is virtually assured.
4) any helicopter can establish a zero knot autorotation, with the rotor rpm stabilized in the green, and no forward speed, in a true auto state (windmill brake state). The rate of descent, however, will be horrendous, and no safe landing can be made from this condition. It is likely to be 4,000 feet per minute descent rate or higher.

OGE hover at lower altitude is a crap shoot. From anywhere near the top of the dead man's curve downward, it is very likely that an engine failure will be a real mess.

[170']

If you visit Penticton BC. You will find hovering autos from 100 to 150' performed all day long in Bell 206's.Zero forward airspeed, just a vertical hovering auto.
A check or two on the collective on the way down.

Very spooky the first time the IP demonstrates it and then easy peasy- Once those guys show you how! and are sitting alongside in case you muff it

I am definitely not the only guy who went through the CHC mountain flying course so corroboration should be forthcoming...

Racing to get forward airspeed is the last thing I'd want to do in the bush!

[Thomas coupling]

This will be interesting...................

[NickLappos]

170'

Chest-beating and youtube videos of light helos flown by experts is one way to determine how to fly your aircraft. Its approved flight manual is another. You get to pick which one you want, but your passengers, should they be foolish enough to climb into your aircraft, trust you to use the right procedures. Here is a copy of the Dead Man's Curves for two helos. As a pro, I made a living producing these curves, with the help of a local fire department standing by, and with the full knowledge that little extra exists when we make these charts. Several times I bounced off the ground, saved by the toughness of the machine I was in and a little blind luck.

If you make your living from flying, you will find yourself driving a taxi should a government inspector see you "youtubing it." For your own fun flying, use 170 feet as a safe hover altitude if you wish, but should the engine quit, don't expect a warm welcome from the ground when you reach it.

Bell 206B:
http://www.copters.com/pilot/pictures/206HV.gif

Robinson R22:
http://www.copters.com/pilot/pictures/R22HV.gif

[170']

Why...I'm pretty NL has bumped into JR and knows what they do!
Now! Where's those ****** hat pins :E

[170']

What is it Nick! You can’t accept that you’re a test pilot/engineer and Sikorsky salesman and have minimal experience in bush work with light and medium helicopters. Which constitutes the biggest part of the industry numerically I guess.

You have a tremendous knowledge about the flight test, development and theory end of this business and I won’t get into a head-butting contest with you in your specialized arena. I’d be taking a knife to a gunfight!

But you are not the all-knowing guru in all aspects of this business, regardless of the lavish praise placed on you by many. I don’t think you have any idea what it’s like for most guys working in the less rarefied atmosphere.
I’d like to know when was the last time you worked a machine in the typical end user mode. Excluding military and offshore clients?
------------
Chest beating - your childish response when cornered?

170’ is just my preferred line length when working 100% legally in an OGE hover in the bush, ever hear of part 133?

Where does taxing driving fit in? Where do passengers. Where do you tube videos?

I work much of the time in a hover between 100 and 230’completely legally and I did it in H models and 205’s for many years, so I guess I spent a lot of time contemplating the HV diagram or dead man’s curve as you prefer.

Not everyone flies high end state of the art equipment, not everyone wants to! Some people are very happy bumming around in Huey’s and whatnot and refuse to be bullied by someone beginning to believe the admiration fawned on him by rookies.

There's no doubt that the IP's in Penticton are experts, but because they are, they help the rest of us to survive in a world of under-powered older machines, because that's what many of the rest of us fly! And in spite of your consistent comments that everyone should upgrade to the latest and greatest gear, the working end of the market can't or won't support it financially.

I post very rarely, and typically only about the work I do. External load operations.

You on the other hand are an expert on everything! and jumped in half cocked saying bull**** like:

1) The Dead Man's Curve is a decent guide to how much trouble you are in. If below 250 to 300 feet AGL when the engine quits at a hover, you WILL crash.

I pointed out that this is done daily, and rather than let it slide you had to jump in and try to bluff your way thru it with insults and bravado!

...

[Ornis]

Courage to spare? Work in air
Engine fails, learn right details
In a chopper, it seems proper
Unless you dare, make a flare
But in a hover, do not bother!
In a plane there's much less pain
RT call, then touch down in stall.

[Senior Pilot]

What is it Nick! You can’t accept that you’re a test pilot/engineer and Sikorsky salesman and have minimal experience in bush work with light and medium helicopters. Which constitutes the biggest part of the industry numerically I guess.

You have a tremendous knowledge about the flight test, development and theory end of this business and I won’t get into a head-butting contest with you in your specialized arena. I’d be taking a knife to a gunfight!

But you are not the all-knowing guru in all aspects of this business, regardless of the lavish praise placed on you by many. I don’t think you have any idea what it’s like for most guys working in the less rarefied atmosphere.
I’d like to know when was the last time you worked a machine in the typical end user mode. Excluding military and offshore clients?

Before you embarrass yourself any further, I strongly suggest that you research Nick's background before he became a test pilot.

He does know what he is talking about as an all round helicopter pilot and good egg.

[170']

Senior Pilot

I know much about Nick Lappos and have shown him the respect he has earned in his field of expertise as a high flying test engineer. That does not give him the right to insult me. I have only a little less overall experience than Nick in terms of years albeit in the simple working arena, and have earned my right to an opinion! Or is that unreasonable of me.

I hold to my position that Nick has little experience in the 'workaday' world of helicopter operations at the typical level as his comments over the years reveal this. I did not try to disrespect his professional standing in general.
But His life has been spent in a different arena!
Perhaps grander in many respects, but the proof that infallibility has no favorites, look at the last video...

[chopjock]

SLFool
Impressive but I'm guessing the number of people who can do this reliably is about as tiny as the margin for error is

I used to do that in my Enstrom. No problem.:ok:

[Senior Pilot]

170'

I see nothing insulting in what Nick posted. I suggest you've either misread his post or seen something that I haven't.

[JimEli]

If you visit Penticton BC. You will find hovering autos from 100 to 150' performed all day long in Bell 206's.Zero forward airspeed, just a vertical hovering auto.


Ask for a full fuel load, engine shutdown demonstration.

[HeliComparator]

HC,

Well, that shows you in your true colours. I trust your friends will show better judgement when they step up to the mark for you.


My point really is that I would like to think that moderators, in a position of power and influence, use that power and influence impartially. I suppose the difficulty is that it's not clear whether you are posting as an individual with your own personal opinion, or as a moderator. Short of having 2 identities on the forum, I'm not sure what the answer is but perhaps, when supporting your friends, you could say that is what you are doing, rather than somehow reflecting the opinion of "the forum" in an official way.

But anyway, I stand by my post. NL has a lot of good points but, just like everyone else, he isn't perfect. It is always dangerous to put total and unquestioning faith in another's opinion.

[170']

Senior Pilot...

Nick's a big boy and more than capable of defending himself.
Is it the role of a moderator to defend his friends? I thought you were supposed to be an impartial bystander simply maintaining a pre-determined level of decorum within the forum. Nick has plenty of support from many fans on this site.Surely you could at least use a different user name to support your buddy and display your feelings as a regular poster, rather than add unfair weight to your thoughts as an Official of the website!

As for your comment of yours regarding Nicks previous experience in 'workaday' operations. He's been in 'flight test' since 1973 according to the latest Bio, so I'm guessing that 'workaday' experience is passed it's shelf life by now? Although I still have trouble putting driving a snake in the 'workaday' world?

A final point. I challenged Nick on one issue, it has morphed into an apparent hatred I must have for Nick, and that's not the case.

I have given him huge credit where huge credit is due in 'flight test' and high level formulae, but argue about his being out of touch with end users at my level. My level being heavily populated with older airframes often driven by older pilots who spend a lot of time in the HV diagram and we do know what we're doing (much of the time)

I'm superstitious by nature so I'm going to hang it up now as I just realized that I have sim Monday and then a 12 hour flight to go hang out in the HV for 30 days again. Luck might have it that I get a double flameout at 200' and **** up the recovery attempt, which would give you and Nick the biggest 'Gotcha' of all time... so that's all from me!

As far as I'm concerned, No hard feelings!

ps: HC posted while I was writing, it wasn't a set-up re your impartiality!

[rjtjrt]

170's posts have been reasoned and moderate and valuable, whether you agree with him or not.
Nick Lappos' post was informative but could well be read as belligerent and demeaning, in anyones language, and this has detracted from what is otherwise a very valuable contribution.
I for one want both these contributors to continue, but in a civil discussion that contributes to this important topic.
Senior Pilot is not helping, this time - can he please steer this back on topic?

[G0ULI]

As a lay person with regard to helicopter flight, what I take from all these discussions is that helicopter flying is inherently dangerous when hovering below 6-700 feet and flying at slow or very high speeds when close to the ground. Pretty much any rescue operation, surveillance or low level lifting work involves flying for extended periods within the performance avoidance curves.

The concept of helicopters seems to have been sold to the general public on their ability to hover, fly slowly and great manouverability together with the ability to drift to the ground like thistledown using autorotation in the event that things go badly wrong at any time.

It seems that the time has come when we should really be considering airships for these tasks since they seem to be capable of similar flight roles and when filled with helium are inherently safer. This is especially applicable over populated areas.

Clearly helicopters are still needed, for example, by the military and search and rescue in the teeth of a North Atlantic gale, but are we using the right tool for the job now that possibly better and eventually cheaper alternatives could be manufactured?

[HeliComparator]

Helicopters only have an "avoid curve" if they are either single engined, or twin engined above a certain weight. Therefore the answer is to fly twins at an appropriate weight which, with some modern types, can be close to max all up weight.

Alternatively, consider just how much risk there is of a gas turbine engine failure. For aerial work over non-congested areas it is probably better to spend the money on top notch maintenance, HUMS etc rather than on the extra cost of a twin. After all, if you eliminate any risk from an engine failure, helicopters and their pilots have a habit of finding alternative ways to crash.

Airships have been around for a long time. If it were advantageous to use them, I sure that would happen. They are not used in these roles for a good reason.

[henry_crun]

I don't understand...

People are describing cyclic back as 'flare' as though it's an exponentially decaying manoeuvre.

I see it as 'gybe'. Sailors will recognise this as a quick change of sail direction across the wind. In this case it is a movement of the rotor disc leading edge from below to above the slipstream.

By suddenly raising the front edge of the rotor disc you get the slipstream flowing UP through the disc, a necessary stage in approaching autorotation if you were in powered forward flight.

henry_crun
dull old engineer

[awblain]

The idea of a quick-reaction airship is an odd one.

The chances of launching airships in Glasgow's windy weather more than 20% of the time is also of concern.

Apologies if that seemed brusque - no offence to raising the idea of airships, just the usefulness of airships.

I contend that the features of loitering airships over the tropical pacific in WWII are especially different from those desired by coppers to whizz about over Glasgow. The US Navy abandoned airships 50 years ago, presumably for good reason.

The criminal community is probably wise enough to run and hide on the airship-shadow side of a building, knowing they'd have minutes not seconds before it moved to bring them back into view, especially if it was to their east, given the prevailing winds.

Instances of arson on parked police helicopters suggest that they are a major impediment to criminals. I suspect that an airship would have less chance of being targeted for malicious damage on the ground.

[G0ULI]

I thought the idea was too good to be true.

[SASless]

Ah....but with an Airship cruising 60-80 Knots and an endurance of a couple of days....quick response is a moot point. The Craft is in the air already....and has been for a day or so.

Some folks need to remember the etiquette in this parlor......play the ball folks.....not the player.

We all have contributions to make....even if we do not always agree.


USN K model Blimp (WWII Tecnhology)

Performance
Maximum speed: 78 mph (125 km/h)
Cruise speed: 58 mph (93 km/h)
Range: 2,205 miles (3,537 km)
Endurance: 38 hours 12 min

[NickLappos]

Were we talking about opinions, 170', it would be interesting, but we are talking about facts. I respect those who must fly into the H-V avoid area (perhaps such as you - we cant know for sure because you do not identify yourself) but that doesn't change the lethality of an engine failure in that region.

[[email protected]]

The video is of a constant attitude EOL, not a vertical zero airspeed one.

It had been taught for many years in the Brit Mil and is a perfectly normal exercise. It is flown at 30 -35 kts until the last 100 feet or so when the attitude is maintained (hence the name constant attitude) and then a check with the lever at about 30' followed by the cushion at about 5'.

It is not, however, even slightly representative of a vertical, zero airspeed EOL from a high hover where the RoD would be much, much higher and that technique would certainly bend the aircraft very badly.

[serf]

From my RFM;

1. Maintain Heading and Attitude control
2. Collective-Adjust
3. Cyclic - Adjust to obtain desired autorotative AIRSPEED (in capitals)
4. Attempt restart
5. Throttle closed
6. Fuel off
7. Flare to lose airspeed
8. Apply collective to cushion landing
9. Shutdown

[HeliComparator]

Lethality seems a strong word. An engine failure in the avoid curve means you are going to hit harder than the test pilot was prepared to accept. That may mean you get a sore back, may mean you damage the helicopter. Yes it may mean you die if you are well into it, but lethality is certainly not assured.

[170']

Ok Nick…You can have the last word on this - immediately after this last post ;-)
It’s deteriorated into a very personal exchange and my participation serves no further purpose. I have said clearly that hovering autos are performed regularly from within the HV diagram and you cry bull**** on that. Nobody has jumped in to support me on this, and at the time I went thru that particular course cellphone cameras weren’t around and I have no video. So unless someone else jumps in to support my claim. You win!
For the record, we’re not talking about operational weights, nor unexpected failures. It’s an engine out drill that’s been fully briefed. But your blanket statement didn’t refer to operational weights either.
The last comment :
(perhaps such as you - we can’t know for sure because you do not identify yourself) seems that now you’re taking me to task for - posting anonymously on an anonymous forum
I’m fairly sure that you don’t believe that Crab-SASless-Heli-Comparator-TC et al are given names. So I can only think it’s a cheap shot to discredit me. As I said in a previous post. I would welcome a closed forum on proon where people provide bona fides before posting.
That really is my final comment for this go-around…

[DOUBLE BOGEY]

Nick I do not know you and have never met you but I think I would like to.

Big respect for 170' earning his living doing things that leave very little margin for error.

I left SEH flying a long time back and when asked by friends why I do not fly privately (on my wages only a SEH is feasible), I simply say "I will probably kill myself because those necessary skills, and courage to use them, have long gone"

I remember doing my first big twin Type Rating. The beautiful and forgiving S61. Training in the old SIM in ABZ and stressing out my Instructor by generally panicking and doing things far too quickly as he slowly and surely weaned me from my inappropriate SEH habits.

However, some things never change, like physics and the theory of rotorcraft flight. Therefore I am somewhat dumbfounded by the bizarre reaction some Rotorheads have to the most simple of concepts.

NR when lost, only comes back by trading energy. The best source of energy is airspeed. In the OGE low speed hover, the immediate need is airspeed to avoid landing heavy. Nicks HoV curves are exactly what this is about so why do some posters get so upset with this. We all know it!!

For MEH pilots like me, the Glasgow crash may prove to be a critical point on how we view flight in the sticky parts of the envelope and in particular, our continued training schedule to develop fully those skills and instincts we may all need for when the 10 to the minus 9 event occurs.

A while back I did a lot of police flying in BO105s and AS355s, spending a lot of time in the OGE hover. I never really considered a double flameout as a real possibility. I don't think we were taught to consider it, rather relying heavily on the OEI concept and escape routes should one donkey stop.

I had two power losses in a BO105 over Leeds at night. The first was caused by my inadvertent beeping down of RRPM, while all time wondering why the NITESUN was not moving. (Both identical coolie hats side by side on the collective).

The second was caused by my large Bobby moving his helmeted head back, fitted a few days prior with a hard visor cover, neatly slotting number 1 power lever into the idle gate while I was keeping station on the PURPs through my RH window.

In both cases I vividly remember the poor little 105, plummeting (P&J readers know this word) towards the houses with me blubbering something like WTF!! and simply not comprehending what was happening. Probably a full 5-10 seconds in both cases before I eventually did the right thing.

(For the second case.....thank you Eric, wherever you are for eventually pointing to the little red lever and issuing those immortal words "Is owt tae dooo wie thar lever" as I scraped across the rooftops at VTOSS.)

Good times spent in blissful ignorance of the probable true horrors that faced poor Dave and his crew that night.

DB

[HeliComparator]

Can't remember if I've mentioned this before, but following the s76 accident in the states where a bird strike retarded both engine control levers to idle, and they failed to enter auto successfully, we embarked on a training programme to cover simultaneous double engine failure. Prior to that, autos were generally done from an already OEI condition whereby the crew were at an enhanced level of arousal.

For me, what came out of seeing many crews perform in the Sim (and knowing it was coming at some point) was a fair degree of certainly that a simultaneous unexpected double engine failure during cruise etc will almost certainly result in a failure to enter auto successfully. It's just human nature and the way we respond whilst at a low state of arousal.

[SASless]

I can recall being the odd man out in tea room discussions about Bell 212's and choosing safe landing areas along the flight path just as in Single engined Bell 205's. My argument was predicated upon a Drive Shaft Failure.....not a simultaneous Dual Engine failure (although the results are exactly the same).

Having come within a Gnat's Ass of having exactly that kind of failure over the North Sea one ugly Winter night while shuttling in the Ninian field using an S-58T....perhaps I was being a bit sensitive to the topic.

Something as simple as a Rubber covered Torch left in a bad place by an Engineer can morph that 10 to the -9 event into reality.

Yet we have to admit....just how many simultaneous dual engine failures have we experienced over the years?

If I am not mistaken....there have been far more Tail Rotor Failures than dual engine failures.

[muffin]

Looking at that video of R22 EOLs reminds me of something I have never quite understood. All the EOLs that I have ever done in the training environment in the UK over the last 15 years have been to a grass surface, whereas every US video that I have seen shows them terminating on a hard surface such as tarmac. Is there any reason for this? If you are going down for real and you have the luxury of a choice, should you pick grass or hard?

[paco]

Less damaged helicopters on runways - the UK seem to like risking hitting rabbit holes rather than wearing out the bottom of the skids :)

Other than that, use whatever is there.

Phil

[SASless]

Grassy areas can be too soft....and if you have any forward speed there is a risk of getting into serious trouble.

If you land on a paved surface....unless you arrive to firmly....there is a very good chance things will turn out okay....if not pretty.

In this situation....the hard choice is better than the soft although if crashing....crashing into the softest things around is the better choice.

[FH1100 Pilot]

HC - It's funny that you mention the PHI S-76 "bird strike" crash. My friend Greg was flying an S-76 for PHI at the time. In the sim in Recurrent soon after the reasons for the crash were figured out, the IP gave him the dreaded dual engine failure in cruise. Greg did what was necessary and put the ship down successfully. Reportedly, he was the *first* pilot to do this; every other one before him crashed.

Now, no doubt Greg is a great pilot (probably even better than me), but so were the other S-76 guys "great pilots" too. I think the difference was that Greg really understood how a helicopter flew. He never verbalized this, but I believe that he instinctively hauled back on the cyclic as he lowered the collective. He knew what Pete Gillies is trying to remind us of: that it's not enough to just get the angle of attack of the blades to a minimum value - you have to get the angle of attack of the disk up to a positive value!

Furthermore, I don't know this but I suspect that the other crews (the ones who crashed) merely lowered the lever and let the RRPM drop to an unrecoverable value. That, or they never got the thing in a stabilized auto until it was too late.

We should be thanking Pete instead of vilifying him. Engine failures don't always happen way up high, with plenty of time and altitude to sort things out.

[Thomas coupling]

He never verbalized this, but I believe

Furthermore, I don't know this but I suspect

Fascinating...guess work I mean.......fascinating....:rolleyes:

[henry_crun]

AStar Accident Shines Light On Autorotation Training | Aviation International News (http://www.ainonline.com/aviation-news/aviation-international-news/2013-05-01/astar-accident-shines-light-autorotation-training)

[NickLappos]

This is a great thread, as it makes us think. Why I weighed in is very simple: Today especially there exists a certain kind of distrust of some of the fundamentals of our existence, think born out of the intellectual freedom the web excites (a very good and powerful thing!)
This thinking that goes something like this:

"Those idiots who make XXX (insert a term like: vaccines, evolution textbooks, public laws, medical procedures, missions to the moon, reports on assassinations, flight manual procedures, investigations of 911 acts. ......) are all YYY (insert a term like: too stupid, on the take, drunk with power, ......) and I know because ZZZ (insert term like: I saw a youtube video, my cousin's Aunt's brother told me, a great web site proves otherwise, Glenn Beck told me,....).

The thing that makes me laugh is that within 100 meters of my desk are world class experts who have spent 20 years of so studying, designing, building and testing helicopter stuff. They (like their peers in France, Russia, Texas, Philadelphia, and Yeovil) have become very expert in ways that operators cannot fathom, any more than they can appreciate what a night rig approach is like.

When I read of a person who basically says "that page in the operating limits section of the flight manual is just bull****, do it this way and you will be so happy you will pee your pants!" I react.

Ppruners, do what you will, but while you do, please respect the flight manual, and those who wrote it. Trust them, they know so much more than you can fathom about the machine, because it is their job. That is not an arrogant statement, it is a simple fact. It take nothing away from your expertise, it is a simple statement of how we are a team, and that we rely on each other to stay safe and productive.

[HeliComparator]

... Reportedly, he was the *first* pilot to do this; every other one before him crashed.


And of course for real, the guys probably had to contend with a face full of bird feathers and guts, and a good peppering with broken plastic - something that is fairly hard to replicate in the Sim!

[FH1100 Pilot]

Oh, Doubting Thomas... I was not there to witness it, but I would never doubt my friend Greg's truthfulness or sincerity in telling me about the sim session. And if it's true that he was the first S-76 sim pilot to survive the dual engine-failure scenario then I, as an experienced helicopter pilot have to make a couple of educated guesses. That's exactly that they are, and that's exactly how I qualified them.

While I've never flown the S-76, I do know how quickly the RRPM decays in other helicopters if you do nothing but lower the collective after an engine failure at cruise. It takes aft cyclic to bring the RPM back, and sometimes a lot of it. If you're starting from 500 feet that doesn't leave you much room or time. While you're working to get everything under control and get into a stabilized auto, you're losing altitude and your choice of landing spots is getting smaller and smaller.

So I won't go as far as to swear on a stack of Bibles in a courtroom as to why my buddy was the first pilot to pull it off and the other presumably good, competent pilots crashed, but it doesn't take a scientist of rocketry to figure it out. All I'm saying is that those of us who actually know how to fly a helicopter flies...as opposed to, say, you... we understand what Pete Gillies was trying to convey to us.

And HC, it's true, the guys who actually crashed the real one had a lot of things working against them. That other pilots in the relatively sanitary conditions of a simulator also crashed is telling...at least to me...and probably to them as well.

[HeliComparator]

... Ppruners, do what you will, but while you do, please respect the flight manual, and those who wrote it. Trust them, they know so much more than you can fathom about the machine, because it is their job. That is not an arrogant statement, it is a simple fact. It take nothing away from your expertise, it is a simple statement of how we are a team, and that we rely on each other to stay safe and productive.

In general of course I agree with you. However in the particular case of the HV diagram they are often not very well produced. I suppose in part it is because gathering the data is a fairly taxing procedure for a TP who values his job (and his back, if not his life!).

The ones I have seen do not properly allow for variations in mass and density altitude, which affect the outcome in reality. On the (twin) type with which I am most familiar, the HV curve is a single line oblivious to any of the above variables. Fortunately, although the graph is in the limitations section, no-where does it say that you shouldn't operate within the blue zone. Which is just as well because every offshore takeoff puts us into it!

Perhaps one answer to having the HV better respected, is to improve the HV diagram.

[Ornis]

Presumably the HV diagram is based on demonstration - what a competent pilot should achieve at MAUW and no wind.

There must also be a purely theoretical diagram based solely on modelling or calculations. How different is it?

[SASless]

Nick,

Did Sikorsky ever run models of the HV's to accommodate head winds of say....20-30 Knots and if so....what effect does Wind have on the shape (Limits) of the HV Curve?

I can recall doing numerous constant airspeed Auto's at Redhill in the Bell 206....holding 25-30 Knots/Miles Per Hour IAS and doing a slight Decel at the bottom and using up all the Collective during the landing. It quite a pleasant ride.

Add some head wind.....and it made for a very short ground slide.....and an almost vertical descent due to the wind effect.

[Savoia]

I can recall doing numerous constant airspeed Auto's at Redhill in the Bell 206....holding 25-30 Knots/Miles Per Hour IAS and doing a slight Decel at the bottom and using up all the Collective during the landing.

Is what you refer to in any way similar to this:

CJGvm1IOgwk

[SASless]

Don't know Mate.....kept my eyes closed the whole way down!:E

When the other guy did that last gulp of air thing filling his lungs to scream....I pulled Pitch to the up stop and held on for the impact.


Actually the video does not completely compare to the maneuver we were doing.....as we did a noticeable deceleration but no where as deep or held as long as in a normal ordinary Autorotation in that there was very little airspeed to trade for RPM or need to slow. It did require some ground slide if the wind was slack....and none if there was some decent wind.

Practice Autorotations in a Jet Ranger are pretty tame.....as compared to the Hughes 500 Series or the BK-117. The Hughes and BK are far more fun and sporty.

[JohnDixson]

Unrecoverable Nr first.

Peter Gillies wrote:

Very few helicopter pilots realize that if, with a total engine failure, the rotor rpm is allowed to fall more than about 5% below low green, the flight is over. OVER. There is no recovery possible regardless of what actions the pilot may take or how high the helicopter is above ground. This fact is not mentioned in the sales literature for helicopters nor in the approved rotorcraft flight manuals. It is not mentioned in any of our FAA publications having to do with how helicopters fly and how to fly them. It is treated as a deep dark secret, unfortunately.

Then, in a second post, reiterated:Easy. As I said in my earlier post, allowing the rotor rpm to drop below the critical point with no engine power to bring it back into the operating range will cause this to happen every time. No exceptions. And as I said before, there is no recovery from this situation. None.

By virtue of several affirmations in this thread, it seems that Peter Gillies has wide experience in the operational side of this business, thus I conclude that this is a case of his being misinformed (by someone equally misinformed).

Truth is, that, though the test standards for US military and civil qualification are somewhat different in the area of transition to power off flight and the testing required to substantiate the H-V plots, one thing is true, and that is, during the course of flight testing any of the machines I have been involved with, this area of testing has always resulted in Nr excursions below the low end of the published green arc ( into the low 80% range ), and I am sure that the test pilot group at the other manufacturers will attest similarly. Thus one's flight is not " over " as Mr. Gillies suggests.

The aero guys at SA in answer to an internal query on an accident investigation some decades ago, did some simulation and opined that there is an Nr number, where at least from the lift vector and angle of attack calculations, the Nr can reach a point where the decay is unrecoverable, and hence ( and this was assumed at full low collective ) you need to put the throttle(s) forward or use your chute. Number was in the 60% range. So there is some margin between where the qualification test crews operate and the point at which the situation turns really dangerous. With an Nr decay rate of 10%/second, though, one does not have all day.

Since either the FAA or the cognizant military test organization gets copies or witnesses all of this testing, the actual Nr behavior is anything but a " deep dark secret ".

As to the H-V subject, I think Nick has said it all. Hard to comment on other manufacturers/models H-V diagrams, but I and Nick have more than a passing relationship with the UH-60, SH-60, all S-76 models and the S-92 models, and for those, I will pass on that the H-V tests were flown to the required structural limits of the machine by pilots who had experience doing that stuff. If one wants to ignore their validity, as at least one poster suggests, have at it, but do have an adequate supply of band-aids on hand.

Thanks,
John Dixson

[HeliComparator]

Does a rigid head, vs a fully articulated head, make any difference? I am thinking of the differing coning angles at least towards the root, between the two technologies at low rpm. I have it in mind that a high coning angle reduces the increased angle of attack caused by high rate of descent.

[PeteGillies]

Hello, John. The information about there being a point of no return came to me from Bell Helicopter years ago. Where is this point? The manufacturers won't tell you and don't want you to try and find it for obvious reasons. Just "keep it in the green." My research says that our FAA requires that the rotor rpm be recoverable within 5% below the lower red line. Some rotor systems may be recoverable below that point. I don't know, and I'm not about to experiment with the engine off line. In our light turbines, the idling engine normally keeps the rotor rpm within the green with the collective full down, so the only way to experiment would be to force the engine to idle more slowly or to flame it out (dumb).

The real world many of us fly in every day is often light years away from the finely tuned world of the test pilot. I admire all of you that possess this fine, sharply tuned knowledge, skill and understanding of rotor dynamics and flying on the edge. My comments, thoughts and suggestions to this forum are meant for all the rest of us who simply fly the aircraft and hope we never have to deal with engine failures and the like.

Pete Gillies

[Savoia]

The aero guys at SA in answer to an internal query on an accident investigation some decades ago, did some simulation and opined that there is an Nr number, where at least from the lift vector and angle of attack calculations, the Nr can reach a point where the decay is unrecoverable, and hence ( and this was assumed at full low collective ) you need to put the throttle(s) forward or use your chute. Number was in the 60% range. So there is some margin between where the qualification test crews operate and the point at which the situation turns really dangerous. With an Nr decay rate of 10%/second, though, one does not have all day.



John: I have heard similar claims of lower numbers and it provides some comfort to know that there may be a small contingency available in the Nr recovery range.

However (and needless to say) one's objective must be to do all possible to maintain Nr within the green.

[Vie sans frontieres]

Why do manufacturers design a hoist facility on their helicopters and market them as SAR aircraft if they know that any normal winching height for SAR is within the avoid curve? Sounds a bit irresponsible putting a facility in place that might encourage users to spend extended periods of time loitering in an area considered unsafe. Should the guy hanging underneath the helicopter take out extra insurance?

Or b) can it not be accepted that for the best to be got out of a helicopter's capability then sometimes its crew have to take the manufacturer's advice with a little pinch of salt? :confused:

[PeteGillies]

Jim -

You are so right! Flame the engine out and then see how the landing works out!

Pete Gillies

[henra]

Number was in the 60% range. So there is some margin between where the qualification test crews operate and the point at which the situation turns really dangerous.


Was that really in a fully developped descent at a high rate?
A transient drop to 60% - 70% (e.g. due to pulling collective while still in Forward flight) while the RoD hasn't built yet is something very different from a constant drop at a high rate of descent. The AOA figures in both cases will be quite different and thus the reaction of the rotor System.

I would be very careful spreading values in the range of 60% as survivable.
For a fully developped descent I have serious doubts. It will depend to some extent on the type of helicopter as well (Disc loading, pitch angle range)

[PeteGillies]

Good afternoon to all PPRuNe Rotorhead readers and posters. I have more thoughts to add to this thread concerning the satisfactory entry to a real autorotation.


It is obvious that many pilots understand the real picture of what will happen if cyclic is not brought back almost instantly when a total-surprise engine or drive-line failure happens.


The problem is the definition of “instantly.” I put it this way: When something happens to your helicopter that you did not purposely initiate, do two things as quickly as you can. 1. Start the cyclic moving aft, and 2. Start the collective (or “lever” as I'm learning to say on this forum!) down towards the bottom. This must be a gut reaction, not a thought-out move on the pilot's part. DON'T take time to troubleshoot the situation before moving the flight controls.


One can take any procedure and find faults with it. Is Cyclic Back needed every time no matter what the mode of flight? Of course not. Hovering or making a low-power descent are two examples. But I'll put it this way: Whatever prompts you to quickly bottom the collective lever in an emergency, real or otherwise, must cause you to apply aft cyclic simultaneously when in forward flight, especially in a climb or cruise configuration.


Do you fly anything powered by the excellent PT-6 Twin-Pac? Take a flight in a sim and ask the operator to fail the one-and-only drive shaft by surprise during powered flight. Unless you apply aft cyclic “right now,” you will probably crash and burn. How do you prevent this? Cyclic Back!


A serious yaw? Big upset? Loud noise? Sounds you've never heard before in powered flight? Applying aft cyclic and lowering the lever will not cause you any problems. AFTER you've done this is the time to try and figure out what has happened. Have you lost the power plant? Do you still have yaw control? Check the panel. Is something wrong? Warning lights on? Horns blowing? SIC screaming? Or did you just dream this...


Dick Sanford, thank you for joining this thread and applying energy management to Cyclic Back. I am going to use your example of trading airframe velocity for rotor rpm. You are so right. For years we've been teaching the three sources of energy available to the pilot when energy from the engine is no longer available, trading energy back and forth as needed, but I've never included your simple explanation in what I've written and lectured about concerning Cyclic Back.


And Shawn Coyle, I thank you too for joining this thread. How often I dream that I could have the knowledge, skills and background that you and Dick have.


I extend my most sincere thanks to every poster who supports Cyclic Back or who is at least open to learning about it. To those readers who have the “My mind is made up; don't concern me with the facts...”, or “Secret? What secret? Everyone in the world of helicopters knows all about this, Pete, and you don't know what you are talking about...” Well, I hope you'll reconsider and come on board with this before you find yourself in a situation where you wish you'd brought the cyclic back more quickly.


Two more things: Probably more than half of my career has been spent flying well within the H/V curve. I've been lucky and never had a mechanical problem while doing this. But those of you who have practiced and demonstrated hover autos initiated from within the H/V curve, in turbine-powered helicopters, have not seen a situation involving REAL engine or drive-line failures.


Several posters have made this point. Try this: Hover at 250 feet agl and have your SIC flame out the engine while you are looking out the window. Now let's see what happens! Even chopping the throttle to idle is a lie. No matter how rapidly you or your SIC “chops” the throttle, the fuel control is in charge of how rapidly the engine heads towards flight idle. The best example is the very popular Allison/Rolls-Royce C20 series found in so many makes and models of helicopters. Wonderful engines. I've trusted them for years and never been disappointed.


Do a hover auto in a JetRanger or 500. Watch the dual tach. Notice something? The needles never split! The fuel control dials down N1 rpm at a rate that will not cause the engine to flame out or compressor-stall. YOU don't control this; the fuel control does.


Each make and model of turbine engine has its own rate of deceleration to idle when the throttle is chopped. The C28/C30 engines used in the 530FFs and LongRangers L-1 through L-4 drop much more quickly to idle, and a needle split usually occurs, but the idling engine power is over 40 horsepower to make the pitch pull look so easy... Same for AS350Bs/Squirrels.


And when you pull pitch...er,the lever...just before ground contact, you are benefiting from the 35 horsepower the C20 series will give you at that time! Do you doubt that? Check your Rolls-Royce technical publications. Look under “Horsepower available at idle.” See the number 35?


How about in the wonderful Huey? Same thing. Could you use over 80 horsepower to make you look so good when pulling pitch at the bottom? Sure you could. And the result makes you look like a super pilot...with a bit of credit given to the “high inertia” rotor system. And for you “Hook” drivers, each of your engines will put out about 300 horsepower at idle. See where I'm going with this?


No, if you want to see just how little time and rotor energy are available to you when the drive shaft fails or the engine(s) flame out, list me on your insurance and then find someone who will flame the engine(s) out OGE when your eyes and mind are elsewhere. This is the real world.


Every “contact” maneuver, whether a practice EOL (see? I'm catching on, guys!) at the end of a normal or hover auto benefits from the idling horsepower from the turbine. This is the same power that makes the rotor blades move at idle! It's always there, making the pilot and the rotor system look good when doing these training maneuvers.


By the way, several posters mentioned situations where the pilot does not have his left hand on the collective. This is true and getting truer as our cockpits demand more and more heads-down attention from the pilot. Lots of things to do with your left hand; frequencies to change, waypoints to insert, switches to switch, and on and on. It's beginning to look like a Space Shuttle cockpit. Except when on autopilot, most of us keep one hand or the other on or very near the cyclic. The collective requires very little attention unless power changes are being made. It is, after all, simply the thrust control, right? In a turboprop airplane it would be called the Beta control (prop pitch control). So it is very common to not have one's left hand on the collective at all times. Here we go; Cyclic Back, and THEN find and lower the lever...er, collective.


A few days ago I was thinking I'd made a big mistake in wanting to share Cyclic Back with my fellow professional pilots on PPRuNe. The snarky remarks were beginning to grind on me. But those of you who echo my thoughts or who have at least been willing to consider them have given me the confidence and support to stick with it. For this I thank all of you.


Pete Gillies

[John Eacott]

Henra,

John D was very careful in explaining that the decay was calculated by the SA guys in response to an accident investigation: not done in 'real flight', and also that the number 'was in the 60% range' which could be 69%!

For you to allude to a drop to 60%Nr can be considered is a bad move on a helicopter forum, since it can morph into an assumption by some and then, before you know it, we're into the 30 minute S92 run-dry scenario where it becomes a firm belief.

I hope that you can see the sense in modifying your post to remove your reference before it becomes assumed to be valid.

[henra]

For you to allude to a drop to 60%Nr can be considered is a bad move on a helicopter forum, since it can morph into an assumption by some and then, before you know it, we're into the 30 minute S92 run-dry scenario where it becomes a firm belief.

I hope that you can see the sense in modifying your post to remove your reference before it becomes assumed to be valid.



Hmm, I'm a bit confused. My Point was exactly that I think assuming 60% might be recoverable is very dangerous grounds. I would consider everything below 75 - 80% sustained as potentially irrecoverable.


When doing the Maths 1g at 60% corresponds to 2,78g at 100%. Even taking into consideration drag effects of the cabin /airframe itself in a rapid descent this means a very significant AoA of the rotor system. Doubtful if you can achieve autorotation at such angles.

[Savoia]

Why do manufacturers design a hoist facility on their helicopters and market them as SAR aircraft if they know that any normal winching height for SAR is within the avoid curve? Sounds a bit irresponsible putting a facility in place that might encourage users to spend extended periods of time loitering in an area considered unsafe. Should the guy hanging underneath the helicopter take out extra insurance?

Can it not be accepted that for the best to be got out of a helicopter's capability then sometimes its crew have to take the manufacturer's advice with a little pinch of salt? :confused:

I'm not sure if taking "the manufacturer's advice with a little pinch of salt" is the best approach.

Helicopter operations (like many other modes of transport) have been subject to continuous development. Since the end of the Korean War in the early 50's (where the helicopter first 'proved' itself) helicopter development (both military and civilian) has been pursued in earnest.

With each new 'generation' there has been a constant and relative increase in performance and reliability resulting in today's models which allow professional SAR organisations (for example) to conduct winch operations in the knowledge that, if flown within the manufacturer's prescribed parameters and in accordance with proven operating procedures, there is every reason to be confident that in the event of, say, a loss of a power from one engine, it remains possible to fly away.

Most (if not all) of the early helicopters (including the early twins) were woefully under-powered and (as with initial single-engine helicopter operations) pilots and operators had to do their best to mitigate as much of the risk as they could but .. this was played-out alongside the need to continue proving the helicopter as a viable vehicle in an increasing arena of activity.

That 'struggle' continues to this day in different parts of the world .. and for different reasons (primarily financial) where operators in regions where helicopter use is relatively new or where a new uses are being pioneered .. and where an operator is under pressure (often self-imposed as part of commercial endeavour) to prove the viability of helicopter use. That's where (for example) you could get a single-engine helicopter being sold to a country with a limited budget and the aircraft is fitted with a winch.

Safety (in broad strokes) is expensive and often it takes an operator and or client a little time develop adequate recognition of the value of 'helicoptering' before they will commit the resources necessary to raise the standard of their operation to the best that the market has to offer (I speak mainly of clients/operators with considerable budget limitations .. such as some of the developing nations .. but not only the developing nations!).

These are just two considerations .. but there are several more.

What I can say is that the RFM limitations are there for a reason and I believe those reasons to be valid and for the benefit of all.

[John Eacott]

henra, you missed quoting the first line in which I tried to point out that JD did not say 60% as a specific number.

That was my issue, and something that I felt needs nipping in the bud.

[SASless]

Do you fly anything powered by the excellent PT-6 Twin-Pac? Take a flight in a sim and ask the operator to fail the one-and-only drive shaft by surprise during powered flight. Unless you apply aft cyclic “right now,” you will probably crash and burn. How do you prevent this? Cyclic Back!

I taught in the 212/412 Sim.....and used that very event in training many Pilots.

I do not endorse your comment about the the "Crashing and Burning" due to the absence of Aft Cyclic during that situation.....in fact I would suggest that just is not the case at all. It might be part of the resolution of a problem but it alone is not the most important part of the response.

Reaction Time is the key.

Followed by use of the most critical response and then doing secondary control movements.

What is far more key to the outcome is the amount of delay in reacting to the failure and thus being able to minimize the decrease in Main Rotor RPM.

I think you put way too much emphasis upon "Aft Cyclic" as again....where and when the failure occurs is far more important and directly affects the amount of time that can elapse without a Pilot response to the failure before the situation becomes unrecoverable.

It is far easier to make up a small loss than a huge loss....that is plain commonsense. Any Helicopter Pilot who has an automatic response to lower the Collective when "Bad" things happen suddenly in a helicopter will probably live to see Retirement as compared to one who sits there wondering what the hell just happened before reacting. Anything you do to keep the Rotor RPM in the Green Normal Range is the right thing to do until you figure out the exact situation you are dealing with.

Rotor RPM is the very foundation of Life in Helicopter flying.....always has been....always shall be.

As you note....low power setting with a moderate IAS....and time is not as critical as compared to a very high Power Setting and a very high airspeed.....or no forward airspeed. In the latter....response time is very critical to defend against a large decrease in Rotor RPM. If moving the cyclic will assist in minimizing a loss of Rotor RPM then it should be done to the extent possible without causing other problems.

I will accept moving the Cyclic Aft will not necessarily hurt you in most situations....depending upon the amount of cyclic movement you make. Too much and you risk chopping off the Tail Boom on a 212.


Your other comment about the lack of Needle Split on some aircraft.......just how do you check for proper function of the Free Wheeling Unit? If you cannot split the Needles then that would be an indication of a malfunctioning Free Wheeling Unit.

If you have done much Maintenance Flying then you know that check is a normal test flight procedure....usually done on the ground prior to take off.

I am thinking you have some good ideas, and genuinely good intentions....but you are using much too broad a brush in some of your statements, in my opinion.

[FH1100 Pilot]

SASless:Your other comment about the lack of Needle Split on some aircraft.......just how do you check for proper function of the Free Wheeling Unit?

You don't, at least not in a Bell 206, FH1100, H-500 or just about anything else powered by the RR250 series.

You do this before start, by turning the main rotor backward. (Haven't we been through this like a million times?)

[JohnDixson]

Henra, that number, in the 60% range was a calculated value. To my personal knowledge, transient power off flight test experience goes down to around 80%. Talking about the in flight data. Power off Nr may well go a bit lower during the landing phase ( although, one better have the machine close to the ground and the rate of descent within limits by the time Nr has drooped to the low 90% range because, well as you all who do these landings know, your ability to produce more than one G, and thus decelerate vertically, is about gone by then).

So, I completely agree with your, may I say, " experienced reluctance " to use that range as usable. I did not mean to covey that idea.

[Two's in]

When the Lynx first came in with BERP blades, every auto was major excursion into some corner of the Nr envelope. Eventually the accelerative Nr nature became more familiar and you soon learned to control Nr with judicious use of the collective. The point being there was no magic collective setting, you worked fast and furious at keeping everything in the governed range on the way down. It's should be the same for every helicopter, you enter autos in the prescribed manner and keep the Nr in the governed range through use of the collective, plus of course whatever you might want to be doing with the cyclic to get your speed/field/flare sorted out at the bottom.

I am perplexed by this "here's what you do with the controls" approach to an auto. There is no fixed solution, just the one that saves your life on the day. But as SASLess has mentioned, without Nr you have no vote or input in the subsequent events, so you really should get that sorted out at the start - assuming you aren't prevented from doing so by some other malfunction.

[G0ULI]

The Robinson Flight Safety video certainly scared me as a fixed wing pilot. 1.1 Seconds for the rotor rpm to decay to a critical level does not seem allow a lot of reaction time if there are other distractions in the cockpit. I appreciate that this is a worst case scenario, but it certainly made me think. The other point made was that autorotation is a pretty quick process when trading height for maintaining rotor rpm. Descent at 1,500 ft per minute doesn't give a whole lot of time to pick a landing spot. Okay, two engines make it more unlikely, but there appears to be virtually zero margin for error. Makes one appreciate just how skilled helicopter pilots are considering the accident rates per flying hours.

[Bertie Thruster]

Flaring the cyclic 'aft' might not be effective if whatever problem you are responding to is turning the airframe backwards.

[DOUBLE BOGEY]

John Dixon and John Eacott - the very fact is has taken you both a few posting to explain the numbers.......and then qualify that by saying you need to be close to the ground at low NR is testament to the utterly misleading and dangerous content of your posts.

Nick Lappos preaches "follow the RFM limitations"

No helicopter I am aware off has a power off limitation in the 60% range.

You cannot have it both ways.

Honestly I cannot believe the stupidity of such posts that seem determined to disprove what has clearly been proven on so many occasions with extensive loss of life. Quite possibly again at Glasgow.

I have a high regard for test pilots but the crap spouted on this last few pages makes me seriously wonder f that regard is misplaced.

Maybe Peter is right when he says "Cyclic Back" is a secret. You lot seem oblivious to its merits.

FYI - LOW RPM AT HEIGHT IS A STONE COLD KILLER. All helicopter pilots know this and every one should be taught how to avoid and recover from this situation.

Talking numbers beyond that published in the RFM and clearly printed on the NR gauge demonstrates that you know the price of everything and the value of nothing. This chest beating arse was responsible for the demise of the S92 in Newfoundland! Rubbish beyond the content of the RFM spouted by people who should know better.

DB

[Grenville Fortescue]

Double Bogey

I don't see where John Dixon or John Eacott are advocating the use of 60% Nr. My understanding is that John Dixon was relaying research findings.

FYI - LOW RPM AT HEIGHT IS A STONE COLD KILLER. All helicopter pilots know this and every one should be taught how to avoid and recover from this situation.

You've just said it's a "stone cold killer" but then you say everyone should be taught to recover from it! :confused: Are you also trying to have it "both ways"?

Talking numbers beyond that published in the RFM and clearly printed on the NR gauge demonstrates that you know the price of everything and the value of nothing.

What exactly do you mean by that statement?

This chest beating arse was responsible for the demise of the S92 in Newfoundland!

Who are you referring to and in what context?

All in all, a somewhat confusing post. :confused:

[DOUBLE BOGEY]

Grenville - if you do not understand my post just do yourself a favour and follow Peter Gillies advice.

DB

[Thomas coupling]

OMG! What a page of posts.
A lot of "big hitters" all turning up at the same time. I have to say this in itself is a reason why I find Pprune fascinating and very enjoyable at times. It's a shame it has to be spoilt by erroneous and undeserving out of control comments from DB at the end of it all and I apologise on his behalf.:=

Peter Guliies - you started all of this :rolleyes: If I may, I would like to commend you for your contribution. You are obviously a passionate end user and (from others) recognised 'expert' in your field. Comments from people such as your good self are always welcomed, I would suggest.
Might I shine light on where,perhaps it has caused enormous consternation from others (me included)?
It is you way with words, it is the way in which you convey your message that has raised a few eyebrows amongst the old and bold amongst us.
Words and statements such as "best kept secrets" and "AFT cyclic" first.....are bound to wind some of us up for all the reasons posted here.
It really boils down to semantics, I would suggest. Perhaps if it could be kept benign, the best way forward for ALL of us to agree, would be to state the following:
In the event of a total power failure or malfunction requiring an entry into autorotation the pilot is required to maintain Nr (ideally in the green:ugh:) by judicious lowering of the collective whilst maintaining attitude.

My reasons for this wording being that ALL helicopter pilots irrespective of their background, are taught from infancy to maintain Nr (it is their life blood). The EASIEST way to retain Nr in ALL circumstances is to lower the collective. Yes I totally agree with you that selecting aft cyclic will also assist, but it is NOT guaranteed is it: Example (as mentioned by you): in a climb (at say 70kts), if the donk stops, one would instinctively lower the lever but one would not wish to select aft cyclic becuase of the unwanted speed reduction. Again in the hover - aft cyclic is not requried. So I think that because there are situations where AFT cyclic is not necessarily essential/mandatory then it should take second place to "lowering the collective" during that instantaneous window of decision making. I hope you understand where I am coming from. You are not wrong in what you say, it is how you have conveyed the mantra.
I have to say that SASless's post in responding to your entry are exactly my thoughts, so too are Two's In. Also excellent posts from the great JD - thanks for your post and good to hear from you.

Finally Peter - I have done hundreds of real engine failures in singles most of which were not at FI, but actually stopped - fuel and all. So HP drag didnt come into it I'm afraid.

And I agree - a real engine failure inside the dead mans curve may result in damage to airframe and/or those onboard. The curve has been designed for the use of Joe average responding at an average response time. The words FATAL are not used when describing operations inside the H/V diagram and never have been in my experience.

[SASless]

DB,


This chest beating arse was responsible for the demise of the S92 in Newfoundland! Rubbish beyond the content of the RFM spouted by people who should know better.



The failure of the Captain to comply with the Emergency Checklist and the Co-Pilot's desire to do so.....by Ditching in a timely manner was the cause of the outcome that resulted from that refusal to ditch.

The descent that followed the first indications of a problem took Eleven Minutes, a conversation with Base Ops took place, and the descent was stopped and a return to level cruise flight was undertaken.

During that process, the Co-Pilot on two occasions reminded the Captain of the Checklist Entry that CLEARLY called for a Ditching.

So despite the Checklist and a Co-Pilot being in favor of ditching.....into very cold and very rough water.....the Captain elected to continue flying.

The existing Sea State, OAT and Wind, and the lack of a Ready Crewed SAR aircraft.....and perhaps a mistaken notion about the 30 minute Fly Dry capability....and whatever guidance the Management Rep provided the Captain....all played a role in the fatal crash that should have been a Controlled Ditching.

SA had run a MGB for an extended time to meet the FAA's Certification requirement.....which we all know now was not representative of an actual "Dry" gearbox. So you need to lay some blame on the FAA as well.

You and HC need to tell the whole story when you bang the Drum about the 92 Crash off Newfoundland. We know the two of you are very much proponents of the 225 which is a direct competitor to the 92. You should be wary of coming across to others as being incapable of having a professional, business like discussion about all things helicopter.

Neither Dixon or Lappos made any comment or suggestion that would lead any Pilot to thinking operating outside the published HV Charts or Main Rotor RPM Normal Operations limits was safe, authorized, or recommended. Just the opposite in fact.

To say otherwise as you have done is not being accurate.

Dixon and Lappos are Professional, experienced, and very capable Test Pilots who know of what they speak. They grant you the courtesy of respecting you in discussing your posts......you should do so in return.

Inquiry finds 16 separate problems in 2009 Nfld. helicopter crash - The Globe and Mail (http://www.theglobeandmail.com/news/national/inquiry-finds-16-separate-problems-in-2009-nfld-helicopter-crash/article587515/)

[DOUBLE BOGEY]

SAS - I consider myself mildy admonished......HOWEVER....

The S92 is a fine ship and there is no intimation in my post that the AC let them down. A poorly timed set of maintenance requirements within the airworthiness constraints contrived to cause their problem. But as you clearly allude to, the mistaken belief that the crew may have had more time to react due to a false assumption may have been the reason for the final catastrophe.

It is to this which I refer when seemingly qualified people dismiss Peter Gillies doctrine to recover NR by challenging the values of NR using alternatives that are not in the RFM. Proffesional they may be but these are dangerous statements made in direct contradiction to the very sound advice from Peter that, unless we are morons, is completely irrefutable. Surely SAS you must agree that the most efficient and sensible way to recover decayed NR is to flare. If you do not have the speed to flare you are in deep do do.

TC please do not apologise on my behalf. Your ridiculous presumption that the cyclic should not be moved in case you need to do a range auto sets you apart from your peers as not really knowing of what you speak. However, being a fair man I will offer you a chance to withdraw that statement and agree that the number one priority is to safely establish into autorotation....followed by assessing your options.

Regardless of the totally distracting irrelevant information posted by some on this forum I have and will continue to follow Peter Gillies doctrine. If the pilots instinct is to trade speed for NR, ASAP, he will always end up in a better position than any possible alternative.

DB

Edited: to say on reflection I did not want to be rude to the two Johns although reading my post this seems apparent. I would just like them to step in line with Nick's posting that the RFM, is our only reference and in doing so hope that the Test Pilots (maybe them) got it correct the first time.

[Nubian]

TC,

Finally Peter - I have done hundreds of real engine failures in singles most of which were not at FI, but actually stopped - fuel and all.

F..k boy! You must be the one pulling up the stats then! That must be an achievement by itself:D

[HeliComparator]

OK SAS, I'll bite just a bit. Yes the Cougar accident was down to not following the correct drill (although of course a more timely technical response to the oil filter issue would have prevented it in the first place). However there was always a suspicion that the publicity machine of the manufacturer could have laid a seed of doubt in the minds of the pilots. Or maybe not, we will never really know.


But what I do know from first hand experience was that, when the subject of 30 mins dry run etc was aired extensively on here originally, NL was far from up front about it. I don't think he actually lied, but he was obfuscating in his replies to clear and unambiguous questions. And he certainly had no courtesy for me, trying to expose the truth as I was. OK he had his job to think about but sorry, trust is hard won and easily lost. For me, that trust is lost because as I said, whilst in many ways he is a great guy (I once had dinner with him and it was a great night), he blotted his copy book big time.

So whilst you and your fellow Americans (and even SP!) can worship him, you will hopefully forgive me if I am not a member of that religion.

[SASless]

The Canadian TSB Report on the Cougar Crash off Newfoundland.

When we talked of a "Shields Down" review of the Offshore Helicopter Industry....this Report would be a good start.

http://www.tsb.gc.ca/eng/rapports-reports/aviation/2009/a09a0016/a09a0016.pdf

Surely SAS you must agree that the most efficient and sensible way to recover decayed NR is to flare.

NO.... I do not agree with such a blanket, covers all possibilities, statement.

As I have said before....in this thread....if you have airspeed to trade....yes....it cannot hurt and does use "energy" that is available.

I have said...."moving the Cyclic Aft in most cases will do no harm...".

I have also said....Cook Book Pilots kill themselves with great regularly.

Knowing instinctively what is the best reaction to a sudden dangerous situation is the key to Survival.....and one cannot do that using a single reaction derived from a "Cook Book" way of piloting.

By the way.....I was wrong.....I count the Co-Pilot recommending "Ditching" three times to the Captain.

Also....the Captain mis-diagnosed the problem and failed to properly assess the indications being provided by the aircraft instrumentation.

There was no discussion in the Cockpit about the 30 Minute Run Dry capability at all. It would appear the Sea State and Weather combined with his thinking it was a pump failure that drove his decision.

I suggest a slow methodical reading of the TSB Report....as it might prove beneficial to one's views on that Crash.

The TSB found issues in multiple areas, Certification, Training, Aircraft Documentation, SOP's, Engineering/Maintenance, HSE, CRM, and Human Factors.

[Tailspin Turtle]

This chest beating arse was responsible for the demise of the S92 in Newfoundland!

DB: This statement is beyond reprehensible. I wish I had the power to ban you from the internet, not to mention this forum.

[DOUBLE BOGEY]

Tailspin Turtle - please explain why that statement is in correct?? I am willing to be corrected!! Seriously.

DB

[Thomas coupling]

DB:
You're nearly there - one more hurdle and that is have some humility and accept that not only are you now saying it (see below), but you might even be believing it:;)
However, being a fair man I will offer you a chance to withdraw that statement and agree that the number one priority is to safely establish into autorotation....followed by assessing your options

Surely SAS you must agree that the most efficient and sensible way to recover decayed NR is to flare. If you do not have the speed to flare you are in deep do do.

Think about that for a while...take a deep breath and ask yourself if you genuinely believe that THE most efficient and sensible way to recover Nr is to flare. If I asked that exact question to a 1000 helicopter pilots in the street and without warning, what do you hand on heart really think they will say DB?:hmm:

[DOUBLE BOGEY]

TC - as I suspect we are both products from the same flight school the technical answer as follows:

1. Lever fully down
2. Flare to recover NR
3. Reapply collective to control NR
4. STABILISE
5. Think - options- checks.

This is for forward flight. Did I pass your test??

I have never had an engine failure in a single. I had a few in a twin. Including some self induced decay in NR. Plenty of EOLs with the engine running at idle - Including from a 500 foot hover. However like I said some posts back these are skills that are 20 years old. I fly large MEHs and up until this accident and the postings by Henra and Peter I had not properly or fully appreciated how fast the NR becomes unrecoverable.

May I ask how you have managed to do a lot of EOLS (I think you said hundreds) with the engine shutdown??

PS I have answered your question and note that you did not answer mine!!

DB

[John Eacott]

John Dixon and John Eacott - the very fact is has taken you both a few posting to explain the numbers.......and then qualify that by saying you need to be close to the ground at low NR is testament to the utterly misleading and dangerous content of your posts.

Nick Lappos preaches "follow the RFM limitations"

No helicopter I am aware off has a power off limitation in the 60% range.

You cannot have it both ways.

I said no such thing.

My post was to henra, suggesting that he refrain from bringing 60%Nr into the discussion since he had misread John Dixon's post.

The inability of some people here to read a post never ceases to amaze me.

Edited: to say on reflection I did not want to be rude to the two Johns although reading my post this seems apparent. I would just like them to step in line with Nick's posting that the RFM, is our only reference and in doing so hope that the Test Pilots (maybe them) got it correct the first time.

Not only were you rude, you were unnecessarily so since I said nothing of the sort. You and HC (with his obsession that any support of Nick is a capital offence) are leading this thread into disrepute, and contributing nothing.

[DOUBLE BOGEY]

John Eacott - please accept my apology. You are absolutely right! My mistake.

DB

[SASless]

DB,

In response to your question to Tailspin.....do you really not grasp the "Wrongness" of your post....as it purely stinks on multiple levels.

Read the entire TSB Report....every word, sentence, paragraph, page, photo, diagram and reference....then check back in with us will you?

Then....read up on the ROE here at Rotorheads....and consider your comments.

When proven Experts are greeted with comments as they have here....no wonder they have to be asked to post.

We lose very good sources of information as a result.

Do you treat the designers of the Comet as harshly.....or the designer of the Titantic.....or the EC MGB Design Engineers....the way you are some here? Every new aircraft has its teething problems with most being unforeseen.

You spoke out of turn.....admit it.....apologize and move on.

I shall make a public apology to Brother Dixon and Nick Lappos.....as I asked them to join this discussion as i felt they had some valuable experience doing Test Work that wrote the Book on several aircraft particularly doing Test Work that led to the compilation of HV Data. I apologize to them for the way they have been treated by some here as it was unwarranted and unprofessional.

They have been very gentlemanly by their lack of response to the insults made here....which speaks to their good Character and decorum.

I cannot say that about those who resorted to insults to them.

Brother Dixon...Nick....accept my sincere Apologies!

Friend Eacott....pointing out some poster's demonstrated Bias is as it should be. Likewise, pointing out the detrimental effect it has on the Forum is spot on.

[HeliComparator]

?.. and HC (with his obsession that any support of Nick is a capital offence) are leading this thread into disrepute, and contributing nothing.

You may give your full and faithful support to Nick as you see fit. What I suggest you (or rather, others) should not do is to require everyone else to have blind faith in absolutely every word he utters. Much of it is of course good. Some of it is not (in my opinion, of course) and it is often rather bullish, which tends to rile.

[SASless]

HC....you reckon continuing to pour gasoline on a fire is a good way to put it out?

Let he who be without Sin cast the first Stone.

You have been chucking Rocks for quite a while and in most cases Nick merely filings them back. Granted he has thrown a few himself over the years but then it takes two to Tango you know.

My advice to all parties of that Bun fight is to withdraw to neutral corners.

With the less than stellar record of the EC Line on the North Sea of late....casting dispersions on the 92 does seem a bit lame you know.

Added to the fact the 92 is out selling the 225 does not lend much credence to the claims of superiority of the 225 over the 92.

Most of us have grown weary of that line of talk and would much rather our attention be directed towards topics that are productive and beneficial to improving the level of discourse here.

[HeliComparator]

HC....you reckon continuing to pour gasoline on a fire is a good way to put it out?

Let he who be without Sin cast the first Stone.

You have been chucking Rocks for quite a while and in most cases Nick merely filings them back. Granted he has thrown a few himself over the years but then it takes two to Tango you know.

My advice to all parties of that Bun fight is to withdraw to neutral corners.

With the less than stellar record of the EC Line on the North Sea of late....casting dispersions on the 92 does seem a bit lame you know.

Added to the fact the 92 is out selling the 225 does not lend much credence to the claims of superiority of the 225 over the 92.

Most of us have grown weary of that line of talk and would much rather our attention be directed towards topics that are productive and beneficial to improving the level of discourse here.

SAS - I don't see any "225 vs 92" here except from you - as you say that has been done to death and will always be ultimately fruitless.

In terms of casting aspersions on individuals, I agree and am happy to desist, but it should be remembered how it started - by some folk attributing near godlike status to individuals and proclaiming that they cannot be argued with. That inevitably begs a counter point to be aired resulting in the unpleasantness you mention. It would be much better if people were left to speak for themselves, and be judged on the content, not on blind faith in everything they utter as seems to be expected by some here.

By all means support a point someone makes by agreeing with them, just don't tell others they mustn't argue because of the reputation of the originator.

[DOUBLE BOGEY]

SAS - actually NO I do not see the wrongness of my posts apart from a misinterpretation of John Eacotts intent.

When very qualified people start posting complex explanations in direct contradiction to what is clearly, I mean very clearly, sensible guidance that is supported by the RFM, it makes me wonder of the motivation of such.

If its just to demonstrate to us mere mortals how little we all really know it is unforgivable. In my view these kinds of statements can lead to pilots believing the bull****. A factor that cannot be ruled out in the Newfie crash.

SAS - you are temporarily blinded by your loyalty to SK. I understand that. However, in my view the Newfie crash would have been very different had they followed the guidance in their checklist. Why the P1 choose not too is a subject for debate but it does not actually matter. What matters s that we at least learn that inappropriate statements, made by influential people, can be severely misleading if believed and followed by the unwary.

In a total power loss the pilot has but seconds to react - do you agree?

If this is the case what possible merit is there in JD posting details that suggest he may have more time than we think??

Honestly I am willing to listen to any sensible argument to the contrary on both elements of my post!!

DB

[Thomas coupling]

DB: I haven't seen any previous questions you require an answer to - have I missed something?
Meanwhile on planet Earth:

I got to thinking about these EOL's I used to do:
I used to do EOL's at the end of every trip with my student (other than the bleedin obvious like taxiing back from IF etc). But there were dedicated EOL trips (I think they were "D20" and "D21 low level EOL's") I did on average one of each of these every week. Each trip usually comprised maybe 10+ EOL's dependent on student capabilities. So at a conservative estimate that was 20 a week minimum for say 20 weeks a year (the other times were other non GFP sorties). Tha makes 400 EOL's a year. A tour in the RN is only 2 years, so 800 EOL's. Three tours in my 17yrs = 2400 EOL's. Now let's all agree that these "EOL's" as I call them are not really EOL's in Peter Gillies dictionary because the engine stayed at FI throughout and even if one did complete the exercise by landing on the ground with "no engine" there was engine drag in there somewhere - he is quite right about that. But you have to agree as I am sure you must have done similar (though not to the same excessive numbers - in the Army with the Mk1) on the day of the race there is absolutely no room for error.
Now - of those 2400+ EOL's, I would suggest that every now and again, naughty Instructors (those who paired up for some SCT flew all these EOL's with the fuel cut off lever all the way back which replicated a total engine failure and a pleasure to fly because of the lack of that high whine turbine in your ears. Again being conservative, let's make it less than 10% of all my EOL's carried out like this, shall we = 200 full on EOL's?:E
So, yes I'm proud to declare that I have carried out hundreds of real engine out landings in my life and not bent one a/c.
Next question buddy?

Oh - PS:Glad to see you have fallen into line vis a vie the Collective and then the cyclic - good boy.

PPS: Take note of this drubbing you are getting from others - only yourself to blame old boy. Take it on the chin and move on.......I do :sad: It's called humbleness.

[DOUBLE BOGEY]

TC - thank you for your nice informative post. When I went through Wallop we did less SEOL (Simulated cos engine at idle) than we should have done because the ground was frozen and the skid shoes were AOG.

I think you have misunderstood my postings and maybe that is my fault but of course, lever down always followed by flare. The fancy variations low evel down wind.......well nice in training. Not sure how it migrates to reality.

As for the drubbing. Thanks for the advice but my position stands.

DB

[SASless]

HC.....it does not matter how it "started"....what is important is bringing it to a close.

DB,

I am no more loyal to Sikorsky than i am any other builder of Helicopters.

I never worked for SA, own no SA Stock, and am not flying any SA aircraft and am not employed by a company that does.

We both know that.

Can you say the same?

This is not about SA vice EC vice Bell vice AW.....but about treating each other with some respect. It is odd that the most vocal are the ones that perceive a slight even when it really wasn't there.

I see some very large Chips on some Shoulders that really do need to removed.



Reaction time.....simply stated.....should be as short as possible commensurate with applying the best or least the least harmful response that goes towards improving the situation.

As to the RFM.....who do you think has the most input on the content of the RFM? Want some hints about who here has been a Subject Matter Expert on at least one if not more than one RFM?

Your reading of Dixon's posts differ greatly from mine. No where did he suggest what you say is correct. He provided the results of empirical data that shows the range at which RPM could be recovered and in no way opined that operating at ranges lower than published in the RFM was acceptable.

Does it not make sense to you that we are given safe limits that are greater than the actual minimum limits? That should not be a difficult concept to understand. That a "thinking" person would understand the one set of limits afforded a "safe" range for normal operations and the other would not is also an easy concept to grasp or at least I thought so until recently.

Perhaps the next time you run into some EC Rotor Design Engineers......you have a chat with them about this topic with them and see what they have to say. You might find they are pretty much in line with the SA guys....or the Bell guys....or the AW guys.

One thing for sure....having had conversations with Lappos....I KNOW he knows far more than i ever dreamed about when it comes to how Helicopters are designed, built, and tested. Likewise, Brother Dixon spent a great many Years doing Test work and flew aircraft well outside the "Normal Limitations" as that was how they arrived at what those Limitations needed to be.

It is a giant step from reading about it....talking about it.....and by God doing it!

I will listen to them that have done it....thank you.

[HeliComparator]

HC.....it does not matter how it "started"....what is important is bringing it to a close.


Bringing it to a close is easy, preventing it from recurring require knowledge of how it started.

[DOUBLE BOGEY]

SAS - sorry bud but its not going to be that easy!!

Peter Gillies

STATEMENT - stated that the unrecoverable NR happens at a certain value from nominal.

MOTIVATION - to help pilots realise just how little time available and the best source of energy to recover - the flare. He hopes this might save someone's life.

Test Pilots

STATEMENT - The Test pilots pop up to discredit Peters claim and state that almost twice as much time is available and back up this claim with lots of data. Read JDs post again. It specifically states Peter is wrong!

MOTIVATION

?????


This has noting to do with EC or SK. Its about misinformation.


DB

PS - I respect the work that the Test Pilots do but maybe their world should never be fully visible to us in Industry. The bit we need is in the RFM. What bothered me most about the posts was the motivation behind them!! The could have said "Hey we tests pilots fully agree with Peter. Time is short so get the lever down and flare if you can to get your NR back. Its nasty at the bottom of the NR envelope"......but they did not say this SAS did they!!

[SASless]

If Peter says 85% and Test Data says 60-70%....which is correct?

If One embraces Peter's number as being the "safe" limit....although higher than the actual limit.....then that is fine as it provides for improved safety.

If One accepts the lower range....but embraces Peter's number....who is hurt?

If One accepts the lower range and then attempts to operate at that number....who is being the Silly Boy?

Again....there was no way to interpret what was said as encouraging using the lower range of Rotor RPM.

Why is it you are hung up over this?

You did make the statement that 8 or 10 prospective Instructors failed their Employment Check Rides because they did not use an Aft Cyclic Input. You did not respond to my questions about the conditions of that event for each of them to include the REACTION TIME and other factors that may have explained their failure to succeed in recovering from the Dual Engine failure you initiated. Simply not moving the Cyclic Aft cannot all by itself cause such catastrophic reactions by the aircraft. It is the "Absolute" certainty in statements made by some there that is the problem....not the general concept of using all the flight controls to trade energy for RPM.

The way I am reading all this....is you embrace the Notion that the Cyclic MUST be moved Aft upon any loss of Main Rotor RPM due to an engine failure or other drive to the Rotor System......and that what others have said challenges that firm hard position you staked out early on.

The bulk of the discussion has been that moving the cyclic aft to use some energy from the Rotor System provided by Airspeed is a good thing. No one is arguing against that. A lot of us are pointing out that there are many situations where that hard fast rule does not apply...does not provide any noticeable increase in Rotor RPM. That directly challenges your hard and fast position.

What we all agree upon is Reaction Time is the most important factor in the successful Recovery of Main Rotor RPM post loss of Engine Drive to the MGB. Second most important is getting the Collective well down....then....followed by use of Cyclic as appropriate.

It cannot be any other sequence of priorities.....if you do not respond that is the end of it.

If you do not get the Collective down to reduce the rate of decay of the Rotor System....then anything else you do will only have a temporary effect.

The secret is to minimize the Loss of RPM and generate as much driving force as possible....which can also include turns as well as decelerating.

Peter did us a service by raising the awareness of this important facet of Helicopter flying but his posts are not the absolute last word on the matter. His concept is quite valid and effective but as in all things Helicopter there is much more to it than his posts have shown.

[DOUBLE BOGEY]

John,

I have apologised to you for being rude. That was not my intention. However, Hendra was not promoting the use of 60% Nr he was specifically questioning that value.

JD brought up that value. You added another (69%) Nice number!!

You confused Hendras post and defended JDs position.

This is exactly the kind of confusion that arises when people start quoting inappropriate values.

The only ones that matter are those printed in the RFM - If this is wrong I am willing to be corrected!!

You accuse me of contributing nothing. Fair enough. However, on the basis of the above just what did you achieve with you posts other than to confuse Hendra by not reading his post and add another confusing number to the mix that yet again does not feature in flight manual I have read.

Once again I did not intend to be rude.

DB

[DOUBLE BOGEY]

SASLESS - I agree with every single word of your last post. In regards to details of training flights - I claim Patient/Doctor immunity...as I am sure you would understand.

If it helps - I am finally on the same page as you!! Apologies for being so tardy!!

Dare I say "Cyclic Aft (but only if appropriate)"

Best Regards

[SASless]

Let's read what Brother Dixon had to say.....I am quoting from his Post. The Bold Print is mine and I have split up his post into individual sentences to make it easier for some to read and comprehend.



The aero guys at SA in answer to an internal query on an accident investigation some decades ago, did some simulation and opined that there is an Nr number, where at least from the lift vector and angle of attack calculations, the Nr can reach a point where the decay is unrecoverable, and hence ( and this was assumed at full low collective ) you need to put the throttle(s) forward or use your chute.

That Number was in the 60% range.

So there is some margin between where the qualification test crews operate and the point at which the situation turns really dangerous.

With an Nr decay rate of 10%/second, though, one does not have all day.

Since either the FAA or the cognizant military test organization gets copies or witnesses all of this testing, the actual Nr behavior is anything but a " deep dark secret ".

As to the H-V subject, I think Nick has said it all.

Hard to comment on other manufacturers/models H-V diagrams, but I and Nick have more than a passing relationship with the UH-60, SH-60, all S-76 models and the S-92 models, and for those, I will pass on that the H-V tests were flown to the required structural limits of the machine by pilots who had experience doing that stuff.

If one wants to ignore their validity, as at least one poster suggests, have at it, but do have an adequate supply of band-aids on hand.




Now let's read what Nick Lappos had to say. Again the bold print and highlighting is my work as is splitting some of his paragraphs.

This is a great thread, as it makes us think. Why I weighed in is very simple: Today especially there exists a certain kind of distrust of some of the fundamentals of our existence, think born out of the intellectual freedom the web excites (a very good and powerful thing!)

This thinking that goes something like this:

"Those idiots who make XXX (insert a term like: vaccines, evolution textbooks, public laws, medical procedures, missions to the moon, reports on assassinations, flight manual procedures, investigations of 911 acts. ......) are all YYY (insert a term like: too stupid, on the take, drunk with power, ......) and I know because ZZZ (insert term like: I saw a youtube video, my cousin's Aunt's brother told me, a great web site proves otherwise, Glenn Beck told me,....).

The thing that makes me laugh is that within 100 meters of my desk are world class experts who have spent 20 years of so studying, designing, building and testing helicopter stuff. They (like their peers in France, Russia, Texas, Philadelphia, and Yeovil) have become very expert in ways that operators cannot fathom, any more than they can appreciate what a night rig approach is like.

When I read of a person who basically says "that page in the operating limits section of the flight manual is just bull****, do it this way and you will be so happy you will pee your pants!" I react.

Ppruners, do what you will, but while you do, please respect the flight manual, and those who wrote it. Trust them, they know so much more than you can fathom about the machine, because it is their job. That is not an arrogant statement, it is a simple fact. It take nothing away from your expertise, it is a simple statement of how we are a team, and that we rely on each other to stay safe and productive.

No one should be insulted by what was said by either of the guys. They both said to operate within the Limits set by the RFM. Brother Dixson clearly is warning against operating outside the established Limits and Nick says the same thing as a Real Helicopter Pilot talks.

I see absolutely nothing wrong with what they said or how they said it.

That is their words pulled from earlier posts.

[Lonewolf_50]

DB, please read again, without hurry, John Dixon's posts. Neither he, nor John E, advocate letting Nr decay to the point of no return. I am grateful for John's joining our discussion. The back and forth between he and henra raise again the issue of what the AoA and the loading on the rotor blades becomes. Their discussion reminds me again of the wisdom of what I was taught: Control Nr.
That's the prime directive.

As to Pete and Cyclic Back as a memory aid:

Pete, if you oversimplify something you may create negative reinforcement. There was a time when we called that "negative training." Your "cyclic back" mantra is no better a simple maxim than the "lower collective" mantra since neither works in isolation.

Unlike our fixed wing brethren, the left and right hand don't influence different flight controls. They influence the same ones! :eek: (G0ULI, work with us here, it's OK! :} ) EDIT to clarify: FW even the right hands left/right stick and fore/aft stick operate different flight control surfaces, while L/H operates power (and often the flaps ...) while in RW both hands end up influencing the flight controls rotating overtop one's head.

Pete, it isn't either / or. As a helicopter pilot and instructor with your deep experience I am convinced that you know better than to teach that those are independent of each other.
When something happens to your helicopter that you did not purposely initiate, do two things as quickly as you can. 1. Start the cyclic moving aft, and 2. Start the collective (or “lever” as I'm learning to say on this forum!) down towards the bottom. This must be a gut reaction, not a thought-out move on the pilot's part. DON'T take time to troubleshoot the situation before moving the flight controls.
False dichotomy.
You have two hands.
You can do two things.
Helicpter pilots work both hands and their feet with some frequency, particularly when flying below translational lift, but that skill set does not magically disappear when flying above translational lift.
Control Nr.
One can take any procedure and find faults with it. Is Cyclic Back needed every time no matter what the mode of flight? Of course not
Thank you, for qualifying the previous point you were making.
I am going to use your example of trading airframe velocity for rotor rpm. You are so right.
It's what I was taught by Navy and Marine Corps instructor pilots over thirty years ago. No big secret. Granted, IIRC all of the birds I flew were "high inertia rotor heads." My carping above aside, I appreciate your energetic crusade on Nr maintenance / restoration. It is much more time critical for the lower inertia head birds.
There are two hands on every pilot. Step 1: control Nr.

If the instructional community teach how to control Nr, (you have two hands!!!!), and pilots learn to prioritize that and then get on with the rest, then that nasty region of decayed Nr where the jig is up will hopefully be prevented, and more people will walk away from, rather than be carried away from, accidents where it all goes wrong in a hurry.

SASless:
FWIW, we learned how to auto by doing run on landings to grass fields at Spencer Field, Whiting, back in the early 80's in the Jet Ranger. I think that's still in the syllabus. I don't remember doing full autos in the Huey ... I draw a blank each time I reach for that memory. I think they used to do full autos in the Huey at Rucker, but again, memory banks have lost that data. Been a few beers since our conference with the Army on that stuff ... hell, a lot of beers. :ok:

[SASless]

During my time at Rucker/Hunter....we did Touchdown autorotations on and off the airfields in the Huey.....lots and lots and lots of them. We did them Solo and with the Instructors. We did them with ballasted aircraft as well as empty. We did "Normal", "180", "Whatever it Takes", "Zero Ground Run"....and when the IP's were not looking ......competitions for the longest ground run.

But that was when we were all headed off to tropical climes where that "Skill" would be needed without a doubt and paid off with many lives saved and aircraft left able to be put back into service.

Times have changed since then I am sure.

That was back in '67-'68.

[Grenville Fortescue]

SASless, thank you for your post taking the time and effort to attempt to decypher previous comments made by Double Bogey. You are a gentleman.



Peter Gillies

STATEMENT - stated that the unrecoverable NR happens at a certain value from nominal.

MOTIVATION - to help pilots realise just how little time available and the best source of energy to recover - the flare. He hopes this might save someone's life.

Test Pilots

STATEMENT - The Test pilots pop up to discredit Peters claim and state that almost twice as much time is available and back up this claim with lots of data. Read JDs post again. It specifically states Peter is wrong!

MOTIVATION

?????



I find the basis for this comparison to be somewhat dysfunctional.

A statement was made by one person and a counter statement made by another. Both are entitled to express their view. What is more, both these perspectives would appear to have originated from the personal experiences of each individual and, so it would seem, each of them is willing to stand by their statements.

If John Dixon states that during the course of his test flying he has encountered Nr values in the 80's range, then he is simply conveying the facts of his experience.

The facts and the truth should never be discouraged.

Professional pilots are meant to be trained so that they will consistently deliver their duty of flying - with skill, discipline and accuracy. If, by making a pilot aware that there may be greater room for manoeuvre in certain emergency situations, his response is immediately to attempt to flout the prescriptions of the RFM, then we are no longer talking about a professional but a rebel and a cowboy, in other words, a non-professional.

John Dixon's relaying of his personal test flying experience was and is not (as far as I understand it) an invitation to depart from the parameters published by the manufacturer and I find suggestions to that effect to be fallacious.

[500guy]

I feel like im jumping into a fight amongst experts here but I will add something. I have done full downs in the R-22, R-44, S300, Bell 47, Hughes 500, and Bell 206. I've been through factory school for the R-22 and the 500. 95% of the auto entries were between 50-80 knots or fairly close to vy. I have done a few at high speeds inthe R-22 and the 500 and it was scary how fast RPM decayed even with quick reaction on the collective. I cant imagine school out there is doing training autos at 90 knots in an R-22 at max power. As stated in the Robinson trianing course it is 1.1 seconds before RPM reaches an unrecoverable point which was stated to be below 80% plus 1% per 1000' (as other have susggested, I'm sure there is a margin there, but it is better that the average pilot not know what that is.

My point is is the training autos most of us have done dont adiquately prepare us for a worst case scenario (high power, high speed, particularly in high speed ships that have low rotor inertia)

SAS, a 212 clipping along at 100knots in cruise is never going 2x vy and has a considerable abount of rotor inertia. So I wouldn't expect Pete's experiences to be the same as yours.

Fly something fast with a low inrtia rotor (like the EC135) and do some autos at high speeds. I think you will see that Pete's advice become quite appropriate.

I dont like how some of you guys are saying "maintian attitude" if you are in a S76 at a 140 knot attitude (or in a 500 for that mattter) you sure as heck dont want to maintain that.

Adjust your attitude to approx. vy. if you are exceeding it would be more correct.

[SASless]

If you will read back through my posts you will see that I advocate using the Flight Controls appropriate to the situation you find yourself confronted with.

I have flown a few Helicopters over my career....and seemed to have survived despite some very serious attempts at killing myself.

The one thing I did that worked towards keeping me around at the end of the day to enjoy a few cold Beers was understanding there was no way to predict what your initial reactions to a sudden emergency would be as very few of us are clairvoyant and thus can see into the future very far.

I agree with Pete, DB, HC, Nick, John, John, and a bunch of others when we talk of using Aft Cyclic as part of the process of regaining lost Main Rotor RPM following a sudden loss of Engine drive to the Rotors.

Where I differ from Pete is I do not see that Cyclic movement as being absolutely necessary every single time as there are a great many situations where it does not apply. I also said moving the Cyclic aft in most cases would do no harm either but would not be very useful.

Airspeed is just one of the factors that affect Rotor RPM in Autorotation. One example is the Bell 206 with its Vne Autorotation Speed marked in Blue not he Airspeed Indicator.

Other Airspeeds that apply are those for Minimum ROD and Max Range.

You are absolutely correct when you say "Practice" EOL's do not compare to the "Real" thing.....and for a number of reasons beyond that you note.

Please don't include me in the "Maintain Attitude" crowd....as I equate that mindset as having the exact same Fallacy that the "Always move the Cyclic Aft" theory....as it does not fit EVERY situation that one might encounter.

If you were doing a Spray Turn and had the Nose of the aircraft well up or well down....and the engine quit.....keeping the same Attitude would prove rather terminal (just choosing one example).

Your comment about adjusting your Pitch Attitude to about Vy is sound.....in most cases but again.....not in all cases.

That is the danger of making "Boiler Plate" statements about helicopter flying....One has to be very careful not to paint yourself into an uncomfortable corner by doing so.

Think back over this discussion we have had.....is that not the case....affirmative statements that did not with stand a critical review and the reaction to those who were challenged?

If you take that same EC-135 you are talking about and do your EOL from Vy....in descending flight....say with about a 1,000 FPM ROD....would you really be hard pressed to survive without the use of a large amount of Aft Cyclic? The honest answer is "No" as you are already in a good descent, at the right airspeed, both the amount and rate of Rotor Droop would be minimal provided you completely lowered the Collective in a timely manner.

Brother Dixson suggested a Droop Rate of about 10% NR per Second....so we can visualize the difference between a 1-2 Second hesitation....as compared to a 3-4 Second hesitation.

Alter the situation to what you describe....Collective up under your armpit....screaming along like a Raped Ape....at MAUW.....have that complete loss of Engine Drive....then hesitate 3-4 seconds before you take any action? Reckon the outcome would be unattractive?

Now put yourself in the other extreme.....HOGE....pitch up under your armpit....lots of pedal in counteracting TR Torque.....and have that loss of engine power. You reckon that aft cyclic is going to do a lot for you?

We have to stay away from absolutes when we talk about flying helicopters....there are too many variables that we have to consider that affect what we do.

[500guy]

I want to comment about the "dead mans curve" as some of you have called it.
We happen to fly 500s doing poweline work, so I keep very close stats on all of the accidents within our industry.

In the 35 years our industry has been operating there have been 17 power losses by powerline construction/repair contractors on the line (either on patrol, below 200feet or in several cases in a hover on the line. In at least 3 cases they were bonded to the wire. All were Hueges 500s, essentialy the only ship used for this type of work in the US. 2 Accients were listed were AUS, the rest are USA.

Pilot Inuries Accident Reference

Minor WPR12LA022

Serious WRP12LA328

None NoReport – Aircraft not substantially damaged

None NoReport – Aircraft not substantially damaged

None NoReport – Aircraft not substantially damaged
Serious SEA07LA135

None MIA93LA055
Serious NYC88LA083

Serious See ATSB Report
None NYC99LA055

None LAX99LA245
Serious MIA99FA158

Minor CEN13FA075
None CHI00FA110

None CHI96 FA099

None No Report – Aircraft not substantially damaged
Minor CEN13FA075

These accidents are literally a worst case scenario for engine failure 100-200' agl low or no airspeed and tons of obstructions, yet in every case the pilot survived.
5 serious injuries
3 minor injuries
9 no injuries
(There were a couple fatalities of lineman on the platform, or carried has HEC)
Also as you can see, in at least 4 cases, they didn't even bend tin.
Please stop perpetuating the theory that a engine failure in the avoid curve is certain death or serious injures.

[DOUBLE BOGEY]

Grenville I had to look up the definition of "Fallacious" as it had me slightly concerned. Apologies but I'm the product of a Secondary comprehensive education.

Just as soon as I had done this I had to do the same for Lonewolfs "Dichotomy"

Are we still on an Aviation forum??

I appreciate the outpouring of support for our industries finest but note that JD has declined to comment. Now it may be that such exchanges (being challenged) is beneath him or it may be he hates conflict. However I suspect it is because there is no motivation justifiable for challenging Peters assertion that NR decay is far worse than most of suspect in high speed cruise as it is a "Fallacious Dichotomy" to risk ones life to prove limits that we all need and then to promote the "extra" bit available in the safety margin.

Having said that I think we have made progress. I now know how to get into Auto (thanks TC).

As an aside, in UK, operations requiring prolonged hovering in a single (such as filming) used to be supported by the Hover SEOL exercise in the OPC specifically because the cyclic input has to be reversed to stand much chance of survival.

Is this exercise included in MEH Police OPCs today. It was not in my time??

DB

[DOUBLE BOGEY]

500 Guy - 5 Serious Injuries and two dead Line Men. How can this not be serious?? It's utterly fallacious. I liked your previous post. The last one sucked!!

DB

[SASless]

Nick's post back about #135, the one with the two HV Charts (R-22 and B-206)....when viewed carefully show the Annotation "Avoid Operation in the Shaded Area". That is a far cry from stating certain death and destruction will occur.

The Charts are generally described by Manufactuers as setting forth parameters where "Safe Landings" cannot be assured. Which does not mean "No Safe Landings Are Possible".

I do believe 500 Guy's short list of events proves that without a doubt.

[check]

We have pages of theories and counter theories, but no one has mentioned the basics. There is no argument about lowering the collective in the event of engine failure but plenty about the subsequent action ie. cyclic aft, forward, maintain attitude, all we need is shake it all about and we have a full house.

Why don't we just say "control the aircraft". With the engine failure and a lowering of the collective there is going to be an element of yaw, roll and pitch, the response will be to correct the attitude which will require a correction in roll and pitch and of course yaw. This should be instinctive now the thought process begins, do I need to slow down, accelerate or turn. The aircraft is now stabilised, what you do with the cyclic now depends on speed or lack off to set up the EOL.

Having had three, one of which was at night this worked for me.

[500guy]

I did not say it was not serious. I said it was not certain death.
the linemen died because they were outside of the aircraft.
As far as the pilots go, and the five serious injuries, one is a friend of mine and he would be the first to tell you that a broken wrist (the FAA clasifies any broken bone as a serious injury) is very different form death.

[Devil 49]

SASless:
A semantic quibble-In most cases it's NOT an "instinctive" reaction when one responds to a situation without conscious consideration. It's situational awareness, prioritizing potential reactions and anticipating the most likely and dangerous problems. Example- flight check w/instructor, one might be a little more aware of wind direction and forced landing areas because you will have at least one power chop with critique. There's a lot of low-effort semi-conscious intellectual contextual analysis proceeding during a flight if you're ahead of the machine. If one is forcing that attention to that decision making process, you're task saturated.

Mr Gillies:
Thank you for refreshing certain theoretical points on residual thrust. It makes a difference in descent rate and angle, but huge change at cushion/pitch pull versus training.
Thoughts on turns to load the disk and increase NR if one was having a really, really bad day?

[[email protected]]

Thoughts on turns to load the disk and increase NR if one was having a really, really bad day?
I think I mentioned this several pages ago regarding an Nr decay demo and it obviously works in the right situation but could not possibly be advocated for EVERY situation (yes Devil 49, I understand that is not what you were advocating but someone here will overreact and assume that):ok:

Lowering the lever first will NEVER be a bad thing (unless you are in a low hover - the exception to prove the rule) because it will prevent further Nr Decay.

Flaring while you lower the lever can often be a good thing but NOT ALWAYS.

Therefore advocating Aft Cyclic as an immediate action for all entries to auto is disingenuous (another one for you DB;)) to the low timers here.

[G0ULI]

The debate about exactly when the main rotor rpm will fall to a point where it is irrecoverable is impossible to resolve because all stalls, fixed wing or rotary wing are the subject of chaotic behaviour. Put simply, given identical failures on two separate days, one day you will get away with it, another day, you won't. The exact point that a stall occurs is dependant on the angle of attack, air density, humidity, temperature levels, wind gust levels and a dozen other factors that could vary. The manuals and red lines painted on the instruments may give some latitude, but they are the values that have been tested and proven to work reliably for the "average pilot".

I remember years ago expessing surprise at seeing the police helicopter refuelling at a local flying club and doing a rolling takeoff. Apparently with the temperature hovering around 30 degrees centigrade, they couldn't take off from their base, only about 250 feet higher but needing a vertical departure with the tanks more than a quarter full. So clearly the weather can have huge effects on performance and I have to conclude that rotor stall would occur at a higher rotational speed in hot weather than on a cold day as just a single practical example of the variables that have to be taken into account.

Naturally fixed wing aircraft have similar limitations, but they are generally along the lines of make sure you have enough runway to get airborne!:rolleyes:

[Thomas coupling]

500guy/SASless:
As devil 49 succinctly put it, there is a lot of mental agility and subsequent dexterity ongoing when the donk stops. We all agree the collective goes down.
Might I suggest that instinctively and in that first 10th of a second, the pilot should/would hold the attitude - why: because he/she is trained to maintain that which is known to reduce the effects of that which is not known (moving the attitude). THEN and only then does the pilot make the next decision which may be a new cyclic position appropriate for that solution.
The transfer from donk stop to moving the cyclic to its final position might appear (a) instant and (b) instinctive but I bet you, the pilot subconciously maintained attitude initially.
Thus (500) K.I.S.S. Keep it simple - lower lever, maintain attitude and then we haven't got to worry about Vy, 2 x Vtoss, half Vmin squared for each damn a/c:ok:
[SAS: Don't demean others by disassociating yourself from the 'maintain attitude' fraternity...its trite and unbecoming of you].

Dead Man's curve:

Afraid to say 500, you didnt just shoot yourself in the foot with that post about H/V eol's.....you blew your damned leg off:D

How about this:

"...As a consequence of ignoring sound technical advice as shown in the FRM, Operations and Limitations Sections, the following were injured and millions was spent repairing damaged helicopters due to prolonged operations in the H/V curve..." Thank God no-one was killed......
Talk about glass half full..............:ugh::ugh:

[Thomas coupling]

Gouli - how do EC135's do rolling take offs then???

[G0ULI]

The chopper I saw had full landing gear. I hadn't considered the case with just skids. But it only goes to prove the point, every aircraft is different and has its own little foibles. What works in one, doesn't necessary apply to another.

[henra]

henra, you missed quoting the first line in which I tried to point out that JD did not say 60% as a specific number.

That was my issue, and something that I felt needs nipping in the bud.


Ahhh, now I got it. Sorry was a bit slow.
I will amend my post to make it more precise, don't konw if it changes much, though.

[Lonewolf_50]

G0ULI
I remember years ago expessing surprise at seeing the police helicopter refuelling at a local flying club and doing a rolling takeoff.
If it had wheels, no big deal. If it had skids ... an interesting day! :} The maneuver you describe might be what we used to call a running take off. Or, a MGW take off. Not sure what it was you saw.
Apparently with the temperature hovering around 30 degrees centigrade, they couldn't take off from their base, only about 250 feet higher but needing a vertical departure with the tanks more than a quarter full.
Gross weight versus DA, versus all other performance factors (to include how much wind and from where) influence the ability to hover in and out of ground effect.
If you can't hover without some droop, do you want to take off? If yes (there will some factors and rules and SOPs that drive that answer) you will want to get a bit of translational lift flowing through the rotor head to reduce power required.
So clearly the weather can have huge effects on performance and I have to conclude that rotor stall would occur at a higher rotational speed in hot weather than on a cold day as just a single practical example of the variables that have to be taken into account.
Do you mean powered or unpowered?

DA influences everything a helicopter does. If your power available versus power required are an unfavorable balance, when you try to lift up into a hover you'll tend to see the NR droop, which is often a good performance flag to put it back down and either get rid of some weight, check that your performance planning didn't have an error, get into the wind ... depends on the situation.

My mentors who used to fly armed Hueys in Viet Nam used to tell stories of having to use an IGE take off run (get some speed and translational lift so they'd have enough power margin to begin a climb away from the forward operating base) when they'd come back to rearm/refuel so that they could actually take off and return to the fight. I am pretty sure SASless and a few others could tell us some real life experiences along those lines.

[[email protected]]

GOULI - cock-all to do with rotor stall but lots to do with engine limits (usually T4/PTIT/T6 on a hot day) - the 'rolling takeoff' will likely have been a cushion creep transition to maximise power available in ground effect.

[Thomas coupling]

Gouli, by you living in Norfolk, it would have been a skidded police helicopter and they do very poor impersonations of rolling takeoffs, I would suggest.
Try again? What was it you actually saw and who told you he had DA issues?

Lonewolf: no please, please no more vietnam stories, please:ugh:

[Lonewolf_50]

TC, given where that flying took place, DA was a non trivial performance variable. Trying to provide helpful answer to our fixed wing friend, eh?
Thread drift from autorotations to max performance takeoff doesn't help the discussion intended, so objection sustained. :ok:

[xlsky]

how do EC135's do rolling take offs then


smooth round pebbles on the tarmac and your take of is rock'n roll

[awblain]

Gouli,

I suggest that the hot-day density dependence reflects nothing more than the relatively marginal nature of helicopter flight. In exchange for those special capabilities, there is a compromise in the ability to carry great loads cheaply.

The power demands to haul vertically upwards are very significant, and when air density is down by about 10% at 30C, as compared with a freezing day, it gets tough. More rotor speed and angle of attack, and more power, wastefully beating up more intense tip vortices, and imparting rotation to the wake is required.

Then again, with fixed wings, the speed at which lift is adequate for flight also depends on the density, although the leeway between getting adequate lift and compressibility of the flow becoming an issue is likely greater.

While different outcomes might be achieved on different days, straying into territory where the outcome is that marginal is probably not a good idea. I would not encourage stalls to be considered as "chaotic". The airflow over the wing is chaotic post-stall, but when the flow breaks down for a certain set of temperature-pressure-humidity-turbulence conditions is very reproduceable. What about the Elmendorf C17 crash, where to paraphrase "the stall warning always sounds here"? It doesn't sound like a message you want to be giving.

Was that a "rolling take off" for a helicopter on wheels, or choosing/being required to accelerate in ground effect? I guess they're effectively the same thing.

[G0ULI]

Thanks all for the clarification of what I witnessed. It all happened years ago just outside London. Probably a Bell Jet Ranger. i haven't always lived in paradise:)

Lived in Australia during the Vietnam war. Watched the news reports every day. Never bothered me as a kid, it did when I was old enough to understand later.

[Lonewolf_50]

Was that a "rolling take off" for a helicopter on wheels, or choosing/being required to accelerate in ground effect? I guess they're effectively the same thing.
Short answer is "yes" more or less the same thing.
As above, we used to call them "running takeoff" but I am not sure if that is only on this side of the pond. Likewise, at the bottom of an autorotation with forward GS maintained, we used to call that a "running autorotation" to differentiate it from an auto to a spot.

[henra]

Gouli,

I suggest that the hot-day density dependence reflects nothing more than the relatively marginal nature of helicopter flight. In exchange for those special capabilities, there is a compromise in the ability to carry great loads cheaply.




In practical Terms you are probably right.
In theory it will make a small difference.
Higher DA means lower IAS of the blade. This corresponds aerodynamically already to a lower RPM. AoA at the same RPM will be higher. Stall will occur at somewhat higher RPM.
Since we don't know to an exactness of 10% what that RPM is it won't matter much, though.

[John Eacott]

Some of the comments and posts on this thread are beyond contempt, especially from supposed seasoned aviators. To insult and demean those who created the Flight Manuals in such a derogatory manner is beyond me.

On my part, this is neither hero worship as implied by HC, nor blind faith. These guys wrote the books that we rely upon to do our job; they come here to share their knowledge in an open discussion and get abused and denigrated.

DB, your post is just appalling: I hope that you are ashamed of yourself and realise that if we never see contributions from the likes of Nick and John ever again then you and HC should go, too.

This chest beating arse was responsible for the demise of the S92 in Newfoundland!

A simply shocking thing to say.

[500guy]

TC.
I'd like to see you install markerballs while staying out of the HV curve.
These aircraft were made to be hovered. The utility industry is proof of that. There is an increased risk when hovering in the curve, sure, but when looking at that risk along with all of the other risks we are exposed to its a drop in the bucket, hardly the difference between a mission that is overall safe, vs unsafe.

The statement in the RFM is little more than a disclaimer not "sound technical adivce". If you need to be there to work, you need need to be there. I dont know anyone who would spend more time there then is needed to do the job.

Before you say, re-evaluate the job, the aircraft, etc..... that is for a different thread....

[pilot and apprentice]

Thomas Coupling
G0ULI (golf zero uniform lima india) happens to be my radio callsign, although I admit it might be deemed unfortunate in the context of this subject. I have fixed wing flying experience and attended the scene of a fatal light aircraft crash in a professional capacity many years ago, which prompted a lifelong interest in flight safety. I was mystified as to what set of circumstances could cause an apparently perfectly functional helicopter to fall out of the sky. It would seem from the answers in this forum and information elsewhere that something such as a vortex ring formation could in theory put a helicopter in such an attitude that the engines would stop from fuel starvation and in that event, the pilot would have very little time to recover the aircraft. I never knew that the main rotor rpm had to be constrained to within such tight limits or fully appreciated that a full main rotor stall would be unrecoverable irrespective of altitude. This thread has been most enlightening, irrespective of some of the irreverent comments. I have had several opportunities over the years to take a flight in a police helicopter, I never took up the offer, although friends thought I was mad not to. I will stick to fixed wing aircraft.

Funny, I don't trust airplanes. Anything that can't stop before landing just isn't safe!

The transfer from donk stop to moving the cyclic to its final position might appear (a) instant and (b) instinctive but I bet you, the pilot subconciously maintained attitude initially.
Thus (500) K.I.S.S. Keep it simple - lower lever, maintain attitude and then we haven't got to worry about Vy, 2 x Vtoss, half Vmin squared for each damn a/c
[SAS: Don't demean others by disassociating yourself from the 'maintain attitude' fraternity...its trite and unbecoming of you].


I had a friend have a non-catastrophic engine failure for want of a better term. He did what we all really do in the real world. As the RPM tried to drop he maintained it, looking for a spot. He used cyclic as req'd to maintain attitude and speed. When it was on the ground and the rotor stopped turning, he was certain it was an engine failure.

That's real life for many of us. No cut and dried directives, pearls of wisdom, or checklists of robotic control movements. Just pilotage.

[G0ULI]

I love that phrase! True or not, it represents the content of many of the posts in this thread, helicopters are apparently flying on the edge of the performance envelope quite frequently. If that is the case, then relatively small changes in density altitude, humidity and temperature could have quite large effects on the performance of helicopters and particularly so with relatively low powered, low rotor inertia helicopters.

[Thomas coupling]

500: I am not demeaning (thats a word that is getting used a lot lately) of your endeavours - far from it. In fact as I told 170' recently, I salute your bravery. And bravery is the word (not bravado) because you sure as hell need it to get your job done, when it is a known, well tested, well tried fact of life that hovering inside the H/V curve ends in tears.....as it did with your previous post statistics.
All I ask is (a) that operators like you recognise the work done by those test pilots who have laid out the danger zones for us mortals to fly around and (B) you don't try to mitigate your reasons for being there in the first place. Given the choice one would never do what you do ...but you have no choice it seems (as I dont know your industry).

PS: Describing the H/V curve as a "Disclaimer" is atleast disingenuous, at most ignorant.
Fly safely 500..................

Pilot and apprentice (you sure you arent rvdt as well?) IF he had done waht you suggested, the drop from his flare would not justify the impact crater size and depth. That is a very substantial deep crater: I'd say 30+ G?

[500guy]

Thank you TC,
We are not to far apart on this.
Every operator I know reccognizes and respects the performance envelope put out there by the test pilots and engineers. However, staying out of the avoid curve is just not a reality to our industry. Like you said, we do our best to limit the time there, limit weight to increase options in the event something goes wrong, and we all do far more than minimum required maintenance.

I called the avoid curve a disclaimer becuase that is exactly what it is. The manufacturer cannot assure a safe outcome if you are within it during an engine failure. If their objective was to keep you out of it they would have put it in the limitations section of the RFM. They know, as well as we do, that inside the avoid curve is where these machines (particularly utility machines) were ment to operate and they woiuldn't sell many if that were a limitation.

We are getting off topic

[SASless]

SAS: Don't demean others by disassociating yourself from the 'maintain attitude' fraternity...its trite and unbecoming of you].


If you are offended by that comment....perhaps some Self Reflection is in order.

Am I walking on your Corns or something?

I prefer to stick with Aviators and that leaves out anyone who embraces Cook Book Methods of Helicopter Flying.

Sadly, for some reason, we seem to be plagued with an over abundance of them lately.

As Cowboy Logic tells us.....lead a Horse to Water but you will have to wait for him to make up his own Mind to drink.

[RVDT]

Pilot and apprentice (you sure you arent rvdt as well?

No he isn't.

Cant think of anyone on here that is a worthy match for you though TC. :ok:

[HeliComparator]

On my part, this is neither hero worship as implied by HC, nor blind faith. These guys wrote the books that we rely upon to do our job; they come here to share their knowledge in an open discussion and get abused and denigrated.


I see absolutely no reason why a TP should be treated any differently from anyone else on here, though I am all in favour of courteous interaction rather than personal abuse of course. TPs have been trained and are just doing their job like the rest of us (well not me, I'm retired!). There are some good TPs and some incredibly useless and stupid ones. The good ones are not perfect, they have good ideas and attitudes, but also some bad ones at times. They are after all just human, and not gods, even if you would wish it were not so.

[Grenville Fortescue]

After the AAIB Special Bulletin was released I stated that in order for the aircraft to meet the CAA's description of a high speed vertical impact with rotors stopped, it was likely that the aircraft suffered a complete loss of power and that, for whatever reason, pitch was maintained on the main rotor. (This being the only probable explanation for such an impact, albeit speculative).

From the examples provided in this thread, and from experience, we know that in single engine flying there is an attentiveness (or at least there is supposed to be) towards the potential for a loss of power. This attentiveness is geared towards rapid response in the event of an engine failure with the certain knowledge that it will be necessary to conserve and manage Nr. The lever is going to have to do down in nearly all cases (apart from a low hover etc.) meaning this action can be taken (along with the necessary cyclic inputs) without delay.

With twins there are additional considerations, principally the second engine, and specifically determining which one has failed. The multi-engine pilot response to a power failure is therefore slightly delayed (in principal) to that of a single engine pilot. This delay is compensated for to some extent by the relatively low risk of double engine failures in twins.

However, on those rare occasions that a double engine failure does happen, it is possible to see how a multi-engine pilot may not instantly take the required action in the same way as a single engine pilot would, and for the right reasons, because the multi-engine pilot must assess the nature of the power failure, even if it is to determine that both engines have failed. In a single, any sort of interruption to powered flight is not only obvious but it is equally obvious that there is no recourse. This is not the "normal" mindset of a multi-engine pilot who will be trained to recover from a power failure with partially powered flight from the remaining engine.

Now that Eurocopter have officially admitted that there is a problem with the EC135 (and related types) fuel indication system and that this problem includes the possibility of over reading, are we seriously looking at the potential of a double engine failure due to a shortage of fuel? A prospect which I had initially discounted as being improbable.

If the ill-fated G-SPAO suffered a double engine failure below 1000ft, at night, I am starting to see how it may have been possible with a low inertia rotor to maintain pitch for some moments after both engines failed - even though a part of me still struggles to accept this.

What I am still unable to envisage is how the rotors stopped so completely prior to impact in order to achieve the unscored and unmarked blades which were apparent at the crash site. We are talking about a few seconds from a loss of power to "blades still"! :confused:

[Thomas coupling]

SAS: That lure certainly worked - I'm out of your peanut gallery it seems....:uhoh:

500: Can you tell me how operators like yourselves get insurance cover? The company I mean not the pilot. Do the insurers know you live inside the H/V curve?

RVDT The reason I asked apprentice and pilot was because you said you were a pilot and engineer, just thought it was a close coincidence.

It getting close to Chrimbo, I finish work on Friday for 18 days - it's a tough life.
Let's see if we can get along in the run up - to set the scene over the festive season. Ooops I ve done it now...heh heh...:ooh:

[henra]

Lowering the lever first will NEVER be a bad thing (unless you are in a low hover - the exception to prove the rule) because it will prevent further Nr Decay.


Coming from a technical side I want to refrain from commenting anything from a piloting perspective.
However, from a pure technical perspective that is not entirely precise, it will not prevent NR decay but it will reduce it.
If done very violently at a very high forward speed you might even be able to achieve a rotor stall when keeping the cyclic forward.
That said no one would do that in reality.
However, maintaining RRPM Comes from the tilted back (read flared) rotor disc vs. the flight path during autorotation. However a tilted back rotor disc will slow down the Helicopter. This has to be balanced in order to maintain the necessary airspeed and thus airflow through the disc. Lowering collective will do that. The sequence in which you establish this stable condition won't matter unless it takes too much time.
In which case both ways if done to the extreme (Only flare without lowering collective as well as only lowering collective without relaxing cyclic) would render you equally dead.


The strange thing in this discussion is that when reading carefully everybody here seems to have the same actions in mind. It's just whereupon the emphasis is laid where the difference lies.
All the more unfortunate that such a harsh discussion has ensued. As (primarily) an interested Reader I hope the emotions calm down a bit and the interesting discussion can continue.
@John Dixson: Thanks for the explanation! I found the discussion about technical limits interesting and therefore thank you for your contribution but I also understand concerns that this might be taken by some out of context (which I hope really doesn't happen).
Any such values will only apply for a certain situation and numbers will vary significantly depending on Type (I would expect see a drastic difference between a lightly loaded S-70 and an R-22 close to MAUW), Weight and circumstances.

[500guy]

Yes they do, our premiums may be higher for that reason, I'm unsure.
As a company our accident rate over the past 10 years is lower than that of the industry single engine turbine accident rate of 2.96 per (100,000 flight hours) as reported by the HAI. (3 year moving average)

the #'s are all that matters to insurance companies

[PeteGillies]

Thank you, TC. The Best Kept Secret obviously does not apply to those of you trained and flying in the UK. But here across the pond we apparently have a different situation. The Best Kept Secret is not that cyclic must be applied quickly to stop and reverse falling rotor rpm. The "secret" is what will happen if the rotor rpm falls below the critical point for the particular make and model and the flight variables that exist at the time power to the rotor fails. Most helicopter pilots, from new to old timers, don't realize or believe that when this happens, there is absolutely no recovery from the situation, and that pilot and passengers are just along for the ride.

I have great admiration for the test pilots who gather the data needed to pinpoint the lower red line on the rotor tach of each make and model, and this lower red line must work for all possible combinations of load, DA, airspeed, c.g., etc., and must have some sort of cushion, too. I respect and teach pilots to observe these limits, and I have no desire to explore them with the engine(s) flamed out.

Almost every poster assumes the pilot will have both hands on the controls at all time. This is simply not true! As I pointed out in an earlier post, the collective is nothing more than a thrust control. All of us at times are not guarding the collective, and if a problem happens the cyclic should be brought aft without hesitation while moving one's left hand back to the collective.

Note that I say "Cyclic back and collective (lever) down simultaneously, or in that order." It is simply wrong in my opinion to prioritize the collective ahead of the cyclic, especially if one's left hand is not on the collective. This would mean not moving the cyclic until the left hand could find the collective and lower it. This would be a huge mistake.

And some posters say that the amount of aft cyclic should be determined by such things as airframe attitude, load, speed, DA, c.g., etc. Why? Why not treat cyclic back the same as lever down? When the engine fails do you stop and think about how far down you should lower the lever? Of course not. You lower it rapidly and fully, and then, if you determine that some pitch is needed for some reason, you raise the lever accordingly.

The same should be true for the cyclic...and even more so. There is no harm at all in starting the cyclic back immediately to stop, not slow, the reduction of rotor rpm, which is all that lowering the lever does.

The first group that needs to know about the Best Kept Secret is the old timers who have never heard of it. This obviously excludes those of you fortunate enough to be trained in the UK. The second group is the flight instructors who have never heard about it, and we've got plenty of them in the business (again, not in the UK). And the third group consists of the FAA and NTSB and the people who write and/or control the publications we depend on such as the PTS, the rotorcraft flight manuals and the slew of FAA-approved helicopter-related publications that do not even mention applying aft cyclic for any reason at all.

Pete Gillies

[Gordy]

I have read with interest this thread and been lurking..... Too many new people, and I do not do well in crowds... :hmm: One thing stands out though:

TCAs a consequence of ignoring sound technical advice as shown in the FRM, Operations and Limitations Sections.........prolonged operations in the H/V curve

You do realize the H/V diagram is NOT in the limitations section of many flight manuals right?

PS: Describing the H/V curve as a "Disclaimer" is at least disingenuous, at most ignorant.

Not ignorant at all. I realize it is different in the UK, but there are a few of us who make a living flying inside that curve. Hence on this side of the pond it is often referred to as the "money curve". We do not go in there blindly, but with much forethought and risk mitigation as far as possible. As 500 stated it best:

Every operator I know recognizes and respects the performance envelope put out there by the test pilots and engineers. However, staying out of the avoid curve is just not a reality to our industry. Like you said, we do our best to limit the time there, limit weight to increase options in the event something goes wrong, and we all do far more than minimum required maintenance.

For the record----I am on Pete Gillies side of the fence with the aft cyclic, have been for many years. It simply buys time and to be honest, my right hand is almost never off the controls.

See you in 14 pages.....

[G0ULI]

Pete
I think that non helicopter pilots such as myself initially visualise the control movements you describe as large, abrupt movements, when in fact nothing could be further from the truth. The various safety videos all make the point that the helicopter flying controls must be handled with authority but also with a light touch. So for example the cyclic controls should never need to be moved to their full extent in flight. I think it is the amount of aft cyclic movement required that is perhaps confusing people. The answer naturally depends on the individual circumstances at the time, the aircraft performance characteristics and the pilot's experience.

I had the good fortune to fly with an RAF instructor who made me form a ring around the joystick with my fingers and thumbs. He then flew a loop, barrel rolls to the left and right, and a stall turn, all without the joystick touching my hands, so demonstrating how sensitive aircraft controls actually are.

So when you say apply aft cyclic and lower the collective lever, you are not advocating pulling the cyclic back into your chest, it is a far gentler but authoratitive movement of the cyclic control back as far as necessary to deal with the immediate situation?

Until the tragic Glasgow crash, I had no idea of the consequences of an engine failure and main rotor stall in a helicopter. In my fixed wing mentality, I just assumed you pointed the helicopter at the ground, picked up speed and carried out an autorotation. The swiftness with which the main rotor rpm can decay and the absolute certainty that below a certain limit, it can never be recovered is quite shocking. Not a secret within the helicopter community, but something that few members of the general public are aware of.

[John Eacott]

That can be the trouble with some test pilots - overburdened with their own self-importance.

I see absolutely no reason why a TP should be treated any differently from anyone else on here, though I am all in favour of courteous interaction rather than personal abuse of course.

Well, HC: which is it? Demeaning and obnoxious comment as per the first sentence, or courteous interaction?

I'm certainly glad I'm not a TP, it would be so difficult to work out how to treat your dissertations.

I made my thoughts on the thread topic plain in page three of this thread, yet the moment I or anyone else pops their head above the parapet to suggest some courtesy towards Nick and John D then Rotorheads with an axe to grind try to make it a willy waving exercise. And a very unseemly one at that.

[henry_crun]

May I suggest that design and manufacturing companies might care to provide a Short Works Course for pilots where they can visit for a week and sit alongside the team who are designing, proving and testing the product?

This might enhance understanding of just how much there is to learn and how Test Pilots are very professional team members following carefully laid out test procedures in cooperation with the entire team.

[DOUBLE BOGEY]

John Eacott - let's get at least one thing crystal clear. The Newfoundland S92 comments I made are based on the intimation that the P1 was continuing flight under the misunderstanding that his MGB had a run- dry capability.

This discussion was, and has been in the public forum since that event.

Someone, somewhere released that erroneous information.

If this is incorrect challenge it.

The "shocking" thing to do is ignore it. As you seemed inclined to do by diverting attention to me. My only interest in this is SAFETY. Safety by following the limits and procedures in the RFM.

My comments about Test Pilots is that when they speak or post it carries implied credibility. I do not believe JD deliberatley set out to convince people that there is more time to irreversible rotor decay than Peter Gillies surmised but I rather suspect that Peters very informative, safety competant post was like a red rag to a bull for the TPs who think numbers are their game.

HC is correct. TPs posting on here are subject to the same scrutiny as are we all.

As for you I have apologised twice, publicly for misunderstanding your post and coming across as rude. You have continued to stick it too me, with I might add, no substance to your posts whatsoever other than you believe my statements to be shocking.

What is shocking is considerable loss off life that may have been caused by ill advised, incorrect, unjustifiable bull**** spoken by those who should know better. So John Eacott, get off your self fed Dobbin, stop the one line rhetoric (one for you TC) and Chunder up whatever is in your guts that's eating you.

DB

[DOUBLE BOGEY]

I have had a couple of PMs calling for me to explain my comments in relation to the S92 and they have caused meto reflect.

Firstly, I in no why implied that Nick or JD had anything to do with the s92 demise.

What I am implying, and stand by, is the possibility that the crew were not in full possession of the facts which caused them to continue flying when their checklist said land IMMEDIATLEY.

The S92 RFM calls for an immediate landing when Oil Px hits zero. That does not mean the MGB will explode IMMEDIATLEY. It clearly must run dry for some period of time to allow for the landing. However, the limits are clearly stated.

If the P1 was fully aware of the nature of this limit, and the likely outcome if ignored, he would surely of ditched. After the events there was strong intimation that crews believed that MGB would run dry.

In this case, decaying NR limits. The limits are clearly stated in the RFM. However, this does not mean that one percent below that limit the NR is unrecoverable. There is a safety margin. However, for us pilots there is only ne limit applicable.

Now when JD choose to call Peters post wrong, due tothe conservative values Peter quoted, JD choose to expose us to the safety limit. This has the potential to perpetuate the misbelief that NR can be safely reduced below the RFM limit.

My post harsh and uncompromising but I hope those of you who view safety asi do will see the reason behind this.

Once again I apologies if I gave the impression that ZJD was responsible or the 92. That was not my intent.

DB