easy question for you chopper guys

[Kerosine]

I am a fixed wing man myself, and have always been safe in the knowledge that when (if) we have engine failure, we can just glide down to the nearest airfield for a cup of tea.

Now with choppers, I'm assuming this all becomes a bit more dangerous. I've heard about 'autorotation', and I'm assuming the blades produce their own lift as it falls? If someone could satisfy my curiosity I would be much obliged.

Thanks

Dave

[Vertical T/O]

Yes that is true. About a third of the blade provides lift. The other 2 thirds are producing drag and the actual rotation power. You have complete control on the way down and all the way to zero knots not like in fixed wing. Assuming we have a landing spot you can safely put the helicopter on the ground with zero ground run. Just look up autorotation on Youtube and you can see loads of videos where they have been landed safely.

[freeride]

Helicopters don't fly, the earth repels them. Simpler explanation :\

[Whirlygig]

(if) we have engine failure, we can just glide down to the nearest airfield for a cup of tea.


Depends how far your airfield is!!! The advantage with a helicopter is that we don't require so much space in which to land so, although we possibly only have a couple of minutes to pick the scene of the accident, there are more suitable open spaces available to us as rotary than with fixed wing.

Cheers

Whirls

[Pandalet]

Assuming we have a landing spot you can safely put the helicopter on the ground with zero ground run.

Don't some smaller helicopters (notably the R22) suffer from a lack of rotor inertia at low airspeed, meaning that you can't trade RPM for cushioning as you hit the ground? So unless you have a fair whack of headwind to autorotate in, an auto without a run-on isn't really an option (without serious damage)?

[cyclic flare]

Don't some smaller helicopters (notably the R22) suffer from a lack of rotor inertia at low airspeed, meaning that you can't trade RPM for cushioning as you hit the ground? So unless you have a fair whack of headwind to autorotate in, an auto without a run-on isn't really an option (without serious damage)?
NO.
The R22 will land as softly as any machine with the right man (Or girl) at the controls. Its all about timing it right. Very easy when you know how

[Gomer Pylot]

Low inertia is only a problem if there is low skill. The AS350 has low low blade inertia, as well as many other models. That isn't a major problem, provided the pilot understands it and takes the proper actions at the proper time. Pulling full collective at 20 feet isn't the proper action, and will result in a less than graceful touchdown. In a 206 it might be recoverable, but there should be no need for the recovery in the first place.

In the event of an engine failure, a helicopter is far safer than any fixed-wing. Poor technique in either will result in bent metal, but even great technique in a fixed-wing can be futile, depending on the situation. Great technique in a helicopter will almost always result in walking away from the scene. At least you don't hit the obstacles at high speed.

[Brian Abraham]

Great technique in a helicopter will almost always result in walking away from the scene. At least you don't hit the obstacles at high speed.
One theory has it that any vehicle that needs to travel at 61+knots to stay airborne is inherently dangerous.

[arismount]

Yes, *theoretically* an autorotational landing following complete power failure is *safer* in a helicopter than is an off-airport landing in an aircraft with complete power failure. However...

...what helicopter pilots tend to gloss over is the great degree of pilot proficiency to pull off a "successful" autorotation. That is, if everything isn't done just right from 50 feet or so to touchdown, severe damage to the aircraft, or even injury to the occupants, is quite likely. This demands a great deal of practice. The problem is, we don't get much practice. Sometimes, none. How many turbine pilots get to do touchdown autorotations with a frequency that is even slightly likely to produce and retain proficiency? How many pilots flying have *never* done a touchdown autorotation in the type(s) they're current in? I rest my case.

Having flown both helicopters and multi-engine airplanes professionally, I can assure you that handling an engine failure on takeoff in a twin requires much less finesse and pilot technique than a touchdown autorotation. Yet, as a twin turbine airplane pilot, I had annual simulator training in the former, while the last time I did an actual touchdown autorotation in a helicopter was some 18 years ago...courtesy of the military.

Undoubtedly the civilian pilots most likely to have a "successful" touchdown autorotation outcome are the folks who are active CFI's. But their level of proficiency will, ironically, also start to decay as they move out of instructing and into larger and turbine-powered equipment. Helicopter simulators are few and far between, and few if any operators do touchdown autorotation training, even in initial qualification; it's just to risky.

The fact that the training is looked on as risky gives you a fair idea of the likelihood of "success" when a real total power failure comes along.

Also conveniently ignored is the tremendous degree of complication to a "successful" autorotation stemming from the lack of availability of a clear, level, and smooth emergency landing site. Quite a high percentage of the time, we fly over trees, slopes, marshy ground, etc., etc. Touchdown on one or more of these types of "surfaces" is again, quite likely to result in severe damage or injury.

In conclusion, far be it from me to come across as a prophet of doom, however I submit that most helicopter pilots greatly overestimate their skill and proficiency, and greatly underestimate the dangers and difficulties involved, in performing touchdown autorotations without damage to the aircraft or injury to the occupants, or to folks or property on the ground. Yes, an airplane off-airport landing involves more terminal energy, however the skill set involved is much less than that required in a helicopter touchdown autorotation; my gut feeling is that you have about equal chance of walking away from either.

[MLH]

You may indeed be able to make that airfield from cruise altitude but, what to do in a fixed wing if the engine quits on climb out at say 200 ft agl? With a heli it's no big deal because of the kinetic energy in the rotor system. Down collective, pedal for yaw and a flare before touchdown.

[remote hook]

Airsmount,

I too have flown both FW and RW commercially, and I'm not sure where you've trained/worked in rotary, but I have done hundreds and hundreds of Full-on Auto-rotations covering every type I fly.

I do agree with your assessment that it takes more finesse and skill to handle an Auto than the loss of one turbine, unless that's a V1 cut... then same same, but different. As long as full on Autos are practiced regularly, the working pilot is every bit as likely to pull it off safely as the working FW counterpart.

Comparing apples to apples, I'd rather have an engine failure in a single engine helicopter than a single engined airplane, weather the terrain below is good, or if it's poor. In the multi, it depends, an engine out in a piston twin at the wrong time can/will be disastrous if not handled exactly right, but in an aircraft like the Challenger, or almost any airliner these days it's a yellow light event. The 212 fully loaded while hovering/slow/low loosing one is trouble, the AB139.... not so much.

At the end of the day, I'll take the helicopter.

RH

[Um... lifting...]

I have to go with arismount on this one and say it ain't all that easy when it sneaks up on you (from 500', you maybe have 15-20 seconds until you're on the ground, one way or another).
I've had the great good fortune to do literally hundreds of touchdown autos in the 206 and the 407, and after a while, one can get pretty good at them (as the instructor from Bell said: "a week of non-stop autos, your grandmother could do them").
However, as arismount astutely points out, it is rare indeed to do one to touchdown in a twin (I never have, in several thousand hours in twins, the bulk of my time), except in a simulator (where the time to pull is only a guess anyway and the consequences of error are minimal) and whenever I have done any auto in any machine (or a simulated engine failure at altitude to be terminated well before landing) it was over a tended field or paved surface (not over trees or the like). In short, planned, by someone (be it myself or an instructor). If you have to put it down in woodland, your last 50 or so feet might be vertical, hoping to avert rotor impact with the trees. That whole tree/rotor interface can break your neck, the loss of wind effect below the treetops may kill your lift and you fall at 32.2ft/s2 (9.81m/s2 in Europe) and hope it comes out alright.
In the end, (and I may not be right), in a single, I scrupulously minimize the amount of time I spend over places where I can't safely auto to a controlled touchdown and when it can't be avoided, I'm nervous as a long-tailed cat in a room full of rocking chairs while I'm there.:=
But, even with all that, I'd rather deadstick a helicopter to the ground than an airplane, but that's just me.

[Kerosine]

Thanks for the input. I've always had a funny feeling about how tenuous your grip on the air can be in a chopper, but that's just through ignorance I suppose. Now I know better!

Might be gettin myself up in one for the hell of it while I'm doing PPL(a).
(Flying a chopper looks so bloody hard though.. jesus.)

Dave

[Pandalet]

For what it's worth, when I saw my first auto during my trial lesson, if the instructor hadn't said "right, entering autorotation", I would have assumed that was the usual way of descending in a helicopter. While I'm sure the real thing is scary as hell, if everything is done properly, it really feels pretty normal (apart from the last 8 feet when the ground suddenly jumps up at you).

[arismount]

remote hook wrote,

>>I too have flown both FW and RW commercially, and I'm not sure where you've trained/worked in rotary, but I have done hundreds and hundreds of Full-on Auto-rotations covering every type I fly.<<

Well, that would certainly make you and the operators you work/worked for very much the exception to the industry rule. Based on my personal experience, which includes 15 years of helicopter flying in two military services and in commercial offshore and EMS work, I seriously doubt that even 5% of pilots flying commercially today could truly make that statement.

[topendtorque]

Kerosine.
funny spelling:confused: We have an outback ditti that starts,

have yer ever bin on the kerosene?
when the metho's runnin low.

Just like swapping from F/W to R/W, easy, just hold your mouth right.

no doubt the other comments will allay your fears of this precise, absolutely essential but extremely basic maneuvre prior to license issue.

For my tuppence worth,
1) I have yet to see anyone who was trained with thorough discipline in autos who couldn't pull one off even without recurrent training some thousands of hours later.

2) for those who fudged through their training for whatever reason, slack instructor or whatever, it's a real hard slog to get them up to speed even when things are set up right and you never really know whether they will pull it off, anytime.

I am not saying though that once learnt properly there is no need for recurrency.

Don't some smaller helicopters (notably the R22) suffer from a lack of rotor inertia at low airspeed, meaning that you can't trade RPM for cushioning as you hit the ground? So unless you have a fair whack of headwind to autorotate in, an auto without a run-on isn't really an option (without serious damage)?

bit cheeky there Pandalet, :ouch: in fact i've seen a R22 cut down several four inch thick gum trees several times before coming to rest right side up, skids juuuust bent.

Blades were still straight but badly rippled.
changed my opinion at the time i'll say.
tet

[remote hook]

remote hook wrote,
>>I too have flown both FW and RW commercially, and I'm not sure where you've trained/worked in rotary, but I have done hundreds and hundreds of Full-on Auto-rotations covering every type I fly.<<
Well, that would certainly make you and the operators you work/worked for very much the exception to the industry rule. Based on my personal experience, which includes 15 years of helicopter flying in two military services and in commercial offshore and EMS work, I seriously doubt that even 5% of pilots flying commercially today could truly make that statement.


5%?

Sorry, I have to disagree there. If you're involved in the Offshore and EMS work, of course you wouldn't, there's no reason to take a twin to the ground. Flying singles there's been one outfit I've worked for that did exclusively power recoveries, and even they did numerous hovering autos from all types of hover heights.

Now, I'm not saying that in any given situation I, or anyone else can be certain of a positive result, but I know several people who've lost the engine in cruise flight, and not only walked away, but left the machine relatively undamaged. Those of us involved in extensive long line work, especially in the mountains, are certainly less likely to achieve the ideal result. That doesn't mean we don't practice those situations as well.

RH

[Pandalet]

bit cheeky there Pandalet, :ouch: in fact i've seen a R22 cut down several four inch thick gum trees several times before coming to rest right side up, skids juuuust bent.

Blades were still straight but badly rippled.
changed my opinion at the time i'll say.


I stand corrected - would love to see the photos of that, if you have any!

[topendtorque]

I stand corrected - would love to see the photos of that, if you have any!

will try, the pilot works with me now, may take some time, silly season here at the moment.
myself down south,
trying to figure out - mundy - wensdy - hyundy
and the sceneree, streuth, no good for a bushie.
cheers tet

[Above Datums]

Autorotation, like all flying related things, is all about style! Enter auto, pick the big the tennis courts at the sixth form girls school, put out a short Mayday call so you sound calm and in control, Flare, Check, level, grease her onto the ground then walk over to the crowd of eager girlys to collect some phone numbers while the crewman rings for a taxi! :ok:


Or more likey........... Swear, enter auto, swear a bit more, pick the big green field and pray its not boggy or on a slope, swear at Mr Bell, scream MAYDAY and your callsign on any freq trying not to swear, flare, swear some more, check, final bit of swearing, level, thump her on to the ground, thank God/Allah/Mr Bell, then walk over to the farmer and start explaining why you just scared his cows and give him your Sqn ops number while the crewman gets the fire axe! :ouch:

[Thridle Op Des]

I think a little realignment need to be made here. It is not possible to compare a complete power failure manoeuvre in a helicopter with a single engine failure in a fixed-wing. The initial question is based on the more suvivable outcome of a complete motive power failure (irrespective of the number of engines you started with). My two major types are the Bell 212 and the Airbus 330. I know without any doubt what I would prefer to have that never-hopefully-in-my-lifetime experience. I might write the 212 off, the insurance company will pay for it, but I know that a stable auto in a 212 is about 30kts down and 70kts forward (minus the wind) as opposed to 170kts forward 60kts down in an Airbus 330. As an ex TRE on the 212, I have found that most pilots will do a survivable but not necessarily pretty auto if required. Most surfaces will take an autorotating helicopter fairly well, If both RR's quit in a 330 then sure I will probably be in a good position to get a relight - as long as I took the reasonable precaution of carrying enough fuel, however just taking the discussion to the limits, a 330 requires 2km of flat surface, preferrably something pretty hard and while it can be done - getting the energy management right to land a dead 330 onto the runway at Lajes from 120 miles out requires spectacular abilities, I know the guy in the rhs on that day - trust me!

Regards

TOD

[212man]

TOD, all that ME sun must be fuddling your memory: 70 kts in auto (for the 212)? I thought it was 60 kts (56 kts is Vy) ;)

On the subject of the Transat glider (you mention), the most bizarre thing that sruck me from reading the report by the AIB was that the CVFDR was shed with the double gen failure (double engine failure)! If any scenario is going to lead to a need to study the CVFDR, surely it must be a double engine failure in a twin engined jet :ugh:

[Thridle Op Des]

Hi 212, Ah ha, I was considering IMC autos to keep the equation the same since we never look out the windows in these high speed planks, I was just giving the 1/2 mvv a bit more margin - that,s my excuse and I'm sticking to it!

Its interesting what doesn't work then you are left on batteries only - Airbus has a lovely comment in FCOM 3 about battery only flight to the effect that it's not supposed to be done for a 'long time' since I guess it will never happen since the Emergency Generator will always be powered by the RAT.

What you doing up this time of night?

TOD

[212man]

In the US delivering our 3 S-92s to Bradley International to be loaded onto an AN-124. They Should arrive Thursday.