SASless

DB,

Let me refresh your memory.


Do enlighten us as to who you think the "Chest Beating Arse" is that is responsible for the demise of the S92 in Newfoundland?

After you do....upon what evidence do you base that plainly held belief?

That is the comment I am holding you to account for....and shall continue to do so until you accept the impropriety of that.

DOUBLE BOGEY

SAS - I have said all I am prepared to say on this public forum and adjusted my position to remain within the scope of the NTSB report, which in hindsight is where it should have always been and for that I thank you.

I will say nothing more on this subject. To do so would be inappropriate and will not serve the prime purpose of my original post which, seeing as you seem to be constantly missing the point, is as follows:

Inappropriate information transmitted from credible sources can be dangerously misleading.

If you do not agree with this statement then I cannot help you any further.

DB

SASless

DB......who is the "Chest Beating Arse"you refer to.....that is the objectionable part of your post that demands explanation.

You continue to refuse to even acknowledge you said it.

Be a Man....not a Weasel.....explain yourself or admit you were wrong for saying such a thing. As you have said several times to others...."You can't have it both ways!"

Lonewolf_50

Helicopter flying isn't for the faint of heart. It's great, though. Give it a try.

Pete: I understand your point. As I pointed out earlier, and you seem to agree, the control inputs by either hand are not necessarily serial, they can be done together. The way you assert that one would NOT use the cyclic if one is not at the moment holding the collective strikes me as contradictory to that point.

Control Nr: that is the prime directive.

I may get slammed for saying this, but perhaps you gents in the civil sector could review what it means when the pilot says "I have the controls" or when there is only one pilot, just who has the controls, and what that means.
Like TC, I was military trained. You remove your hands from the controls, if ever, very briefly to do things like switch radios, write on kneeboard, copy clearances, etc. Then, your hands are on the controls if you are the pilot flying.
Please explain why this is not what you teach. Or did I misunderstand you? If so, apologies up front.
I realize that there are a lot of automation and autopilot features, but resting your hand on the controls while the aircraft is flying with automated assistance is not a taxing thing. I've done it plenty on those hours long drone-a-thons as radar or ESM picket, airborne, one each.
TC:
Agreed, but it's back on after a brief excursion.
I'll ask any of the experienced pilots and instructors here: how many fractions of a second does it take to get a left hand not on the collective back onto it to manipulate it?

Pete's point about 'not waiting' to control Nr with cyclic if necessary is a good one, if one is caught out ...

GF:
Really? When you get a power loss, do you always know it's only one engine when you are in a twin? Control Nr.
No, it isn't, since the word you used there "compensated" has nothing to do with flying and engine failures. It may have to do with risk calculations and insurance actuarials.
Not quite. Single or twin, the correct response is: Control Nr, fly the aircraft.
I'd say your reasoning has nothing to do with flying, and makes twin engine helicopter pilots out to be idiots.
I can't buy your line of reasoning.

Do you fly helicopters, GF?

awblain

Gouli & Lonewolf,

Having lightweight rotors - which is effectively all low-inertia means, give or take some ability to pull some mass inwards through clever composite structures - isn't necessarily a bad thing.

It does reduce the amount of energy stored in the rotor, potentially allowing it to winddown more quickly.

On the other hand, it saves fuel by having of order 100kg less to carry around, allows a quicker acceleration of the rotor with changes in power/airflow at low pitch should it get slow, makes debris a little less dangerous in the event of it coming into contact with something, and provides less gyroscopic restriction on the motion of the aircraft. By reducing the rotor mass, all of the bearings and shafts can also be made lighter, making the whole system more efficient. When there's not a huge overabundance of power available, as you say every 50kg counts.

Lonewolf_50

Thanks for your post. I am modestly familiar with the weight bogey chased by aircraft design engineers, and chased^2 by helicopter design engineers!

@ chopjock:
About your RC drones ...

Please look up the term "scaling" as it relates to design.

Also for your consideration: on all of the helicopters I flew, we had in the maintenance manual seasonal adjustments for autorotative Nr as a factor in control rigging. Each maintenance check flight I ever flew had at least one autorotation within a test profile, which was matched against GW, conditions of the day, and compared to the performance marks in the manual. A slight lengthening or shortening of control linkages were sometimes called for to get it right.

If you start messing about with control linkages to get negative pitch, you can run into some unintended consequences.

This was over 20 years ago, but I cannot forget an example in an SH-2.
I learned that a misrigging could create ground resonance due to "flat pitch" (no, not quite flat) trying to slightly pull the helicopter into the ground. We noticed it due to the wheel struts being compressed and the bird beginning to shake a bit. Shut down, worked with maintenance, and a few control rigging adjustments were made to remedy that error.

Your idea on pitch changes and rigging is likely to have undesireable outcomes.

DOUBLE BOGEY

SAS, my definitions in the context they were used:

CHEST BEATING

Making technical statements just to prove ones own knowledge - I am guilty of this too.

ARSE

The pointless nature of the content. Not the man saying it!
(as in........a load of arse!) - My wife reckons I spout a lot of this.


I really hope you did not think I was calling JD an Arse!! If my grammar led you to think that then of course I will apologise immediatley to you and JD.

I hope we have cleared that up!!

Lonewolf_50

DB: your missus probably also told you "when one has dug one's self into a hole, it is usually best to stop digging at some point."

DOUBLE BOGEY

Lonewolf - I have dug no hole. I stand by what I have said. When people make statements about capabilities beyond that published in the flight manual is, and always will be "ARSE".

Surely even you lot can form sufficient metal dexterity to form the link between:

This:



and this:

Quote:

"The pilots had been taught during initial and recurrent S-92A simulator training that a gearbox failure would be gradual and always preceded by noise and vibration. This likely contributed to the captain's decision to continue towards CYYT."

and this:

Quote:

The pilots experienced difficulties controlling the helicopter following the engine shut-down, placing the helicopter in a downwind autorotative descent with main rotor rpm and airspeed well below prescribed RFM limits. This led to an excessive rate of descent from which the pilots could not recover prior to impact.

and the merits of Peter Gillies posts.

If advocating that we follow the limits in the Flight Manual and stop making claims beyond those limits.....is digging a hole then I will gladly dig.

There is none so blind as those that cannot see!

Lonewolf_50

Since I didn't see anyone advocating not following the Flight Manual ... I see just fine, thanks.

Example:
If you bop on over to the V-22 discussion thread, and the back and forth about VRS, someone posted a link to the test flying done by test pilots, at altitude, who discovered a few things about how the bird reacts to VRS. That isn't something that goes into the flight manual "hey, go do this!" but it is useful information to understand the limits of a given airframe and a further admonition to do as the Flight Manual says, which is avoid to VRS. There is no harm in posting that.

Likewise, what John commented on regarding about where the engineers estimated the point of no return being for a helicopter he did some test flights on, I see that as further caution to make damned sure one doesn't even approach that region of Nr, but instead keep the Nr in the green.

With the various points made on how dire it is to reach that point of no return, I suppose the Flight Manual could include a memory item:
If Nr is now stalled, recite out loud as follows:
Our Father, who art in heaven, hallowed be thy name ...

But the point is not to get there.
Control Nr. Fly the aircraft.

Thomas coupling

DB: You're losing ground buddy. I had an element of support for you even before this debacle with SAS and JE - even when you were slagging me off left right and centre. But now it's fading fast.
For some reason you won't admit the error of your ways either in what you have said or how you practice your trade (denying the first rule of flying: keep the rotor in the green by lowering the lever first).
Are you so proud a man that you can't take the hit? Are you afraid of what people might think of you if you are wrong? Accepting you are wrong is what makes the man - no? [And before you start, I have openly admitted my misgivings on several other threads as much as I hated it. It comes with the territory ].
C'mon, give it a try....we'll still like you afterwards - ish You might even feel enlightened..................

helifreddy

Hello @ all.
I am a retired helicopter pilot who worked 35 years as IP in twin engine helicopters and have some EC 135 experience too.
What we trained in cruising flight, safe altitude, was:
In case of visual/audio warning of OEI or Low NR:
Lower collective immediately,aft cyclic to maintain RRPM and to reduce airspeed to Vy (60-65 KIAS).
During this manoeuver check RRPM and N2 Rpm of both engines (other indicators and WL too).
If OEI, pull collective to continue single engine,shut down proc.for failed engine.
If AEI, continue in the AR,follow autorotation procedure.

In regard to the low RRPM,I demonstrated max.range in AR with RRPM minimum (red line).If RRPM would be much lower,its true,it will not recover anymore. But I think it should be more than 5% below minimum.
For the crash in Glasgow I have no explanation at the moment.
I think we have to wait for the accident report.
Fly safe and best regards.

Grenville Fortescue

Lonewolf 50

Firstly multi-engine pilots are not "idiots" in my view and, while how you arrived at such a conclusion may be fascinating for some, it holds no interest for me. The comment itself was delusive and the connection, however made, does not reflect my own belief. Secondly, my career is well known among those with whom I have served and I feel no obligation, or interest, in qualifying this to you. My comments will stand or fall on their own merit.

My observation is based on the fact that in multi-engine operations (MEO) the process of response to an engine failure contrasts with that practiced in single engine operations. This contrast centres about the need to verify the engine failure in MEO and which process involves steps which (for the previously stated reasons) are unrequired in a single.

This consideration accounts for how it may be possible to encounter a delayed response to the control of Nr in a double engine failure scenario in a twin engine helicopter (something I have witnessed numerous simes in the sim). Bleating on about Nr control is irrelevant in this context because my previous comments presuppose this as a trained response. In other words, Nr control in response to a total loss of power, is axiomatic, or supposed to be, and which was (for me) not the issue. It is what tends to happen before Nr is controlled that I am highlighting.

If you cannot appreciate that in MEO there is a need to "verify" the malfunction (not at the expense of responding to Nr control, but which consideration in the specific scenario mentioned may in fact lead to just that) and that this same process of verification is more readily accomplished in singles, then clearly there is nothing more I can say to help you appreciate my observation.

TorqueOfTheDevil

The other exception is LL cruise flight, where dumping the lever may put the aircraft so low that it's impossible to flare without striking the tail. Hence the UK mil teaching which is (I understand) to prioritise flaring on entry to a LL EOL.

Nubian

TC,

Just the kind of response I had expected from you.

Say no more.

or in your own educated way, DUH!

Anyways, get well soon!

DOUBLE BOGEY

Dear Nick,

For some inexplicable reason PPRUNERS have formed the impression that I somehow blame you for the S92 crash. This is due in most part to my indvertant link to the detail in the NTSB report intimating that the crew training may have led them to beleive that they could continue beyond the safe haven of the RFM limitations and procedures.

If you have this impression from me it is not true and if I have somehow implied that I apologise completley.

Reading back through your posts You and I preach the same thing. Follow the bloody flight manual.

I may have made a mistake attacking John Dixons post about low NR but I really beleive when you guys speak...it matters and people listen.

I worry about posts that suggest there are alternative values to minimum NR and of course I am not naive enough to realise that there is a safety margin, thanks to the efforts of you guys. However there is a continued danger present when values are quoted beyond true capability.

DB

Devil 49

DAPT said:

"Robinson video vs UK military primary training
The explanation and graphic video is the best way to understand how a helicopter can drop like a stone with rotors not turning.

The only way for that to happen is delayed entry into autorotation it does not matter where you received your training."

There are other factors that could make the autorotation a hopeless maneuver- control rigging, for example. Once flew a fleet spare (twin) on an autorotative check that wouldn't maintain NR in the green as I pulled power back in an established AR profile. Don't know how low it would have fallen with with further power reduction.
How often do you check yours?

rotorfossil

Ref cyclic first or lever first. Bearing in mind that there are occasions when aft cyclic first is perfectly acceptable and others when it definitely isn't, such as in the climb, on the approach or at any time when the speed is low, it has always seemed to me that the best teaching is to lower the lever (damn quick) and INITIALY maintain the pitch attitude with the cyclic.When you have decided what you want to do next, like increase speed to increase range or reduce speed to lose it, THEN change the attitude appropriately.To try to teach different initial reactions when the priority really is to get the lever down is not likely to succeed. History seems to indicate (particularly in low inertia types such as the R22) that people who lower the lever, whatever else they do, generally live, but people who don't, die.I agree that in the special case of engine failure in a single at high speed and just above the avoid curve, both together seems to work.

Lonewolf_50

GF:
It's the way you wrote it. I didn't find your mixing systems level risk assessment with actual flying in response to a power loss (twin or single) to be a lucid way to frame your position.

I have flown both singe and dual engined helicopters. The advantage to having two engines is that sometimes, when you have a loss of power, you have a second engine to help you do something other than fly that auto down to the bottom. Fly it, which means control Nr first, and then see what your engines are giving you. If it's your good day, you can use the good engine to fly you home. If it's your bad day, you are flying as you should be and have a chance at a decent auto all the way down. (and on your really good day, you have some altitude and time for a possible restart, depending on why the engine stopped. The whole time you are figuring this out, you are controlling Nr, flying the bird. Helo pilots can multi task ... it's in the nature of helicopter flying).
Really? Are you telling me that you don't teach that control Nr comes first? (Say it ain't so).
Even with a partial power loss, or a compressor stall in one engine, or a roll back in one but not both engines, the First step is Control Nr
and the implied associated first step is fly the aircraft.

Time delay in acting is another topic.

Nothing further. Out.

PeteGillies

Thank you for your comments, Gouli. No, I do not advocate making any extreme yanking-type movements of the cyclic. But any delay at all in applying aft cyclic can be critical because this is the ONLY control movement that will lead to stopping and reversing the falling rotor rpm. The movement should be as instant as possible and done so there is no doubt that positive g's are being applied to the airframe.

When drive to the rotor system is lost, the rotor rpm begins to fall instantly and the reduction of lift causes the nose of the helicopter to fall, or pitch forward. This in turn acerbates the problem of air coming through the rotor from top to bottom. This along with the drag of the blades and gearbox, etc., is causing the rotor rpm to fall. Add to this the negative g's applied by lowering the lever which also increases the downward pitch of the airframe and rotor, and you can see where this is going.

Applying aft cyclic quickly is the ONLY way to reverse this chain of events.

THIS is the critical situation that Cyclic Back addresses.

Two posters have said that aft cyclic should not be applied during a climb. A vertical climb, no, but in every other type of climb, YES! Why? Because indicated airspeed is of NO VALUE AT ALL at the moment power is lost. The ONLY airspeed that matters at that moment is the airspeed over the wings, which, of course, means the rotor blades. Cyclic Back done in time will catch the rotor rpm before it drops to the critical point. NOW you have a flying machine and can then dial in whatever airspeed you'd like, but be careful when nosing over because the rotor rpm you've just saved will disappear in a heartbeat if you push over aggressively. Keep an eye on the rotor tach as you lower the nose to gain speed.

In the case of the two law-enforcement accidents I investigated, the pilots said they lowered the lever the moment the engine failed and then immediately applied forward cyclic to gain airspeed. Both of these accidents happened when the helicopters were on a routine climb at about 400 ft. agl and somewhere between 60 and 80 knots. The rotor blades were barely turning when the ships hit the ground. Damage to the blades was "downward" bending, not damage associated with the blades turning and hitting something hard. Both ships burned. Both crews survived but barely. One blade from one accident showed NO DAMAGE AT ALL per the NTSB report. And both ships crashed badly on the left side, the pilot's side.

The application of aft cyclic in time would have given both pilots a controllable helicopter all the way to touchdown. But instead they were just along for the ride. This was not pilot error! They had never heard about Cyclic Back. Both were high time and one was former military.

Pete Gillies