Are engine failures always recoverable in helicopters?
 

Assuming there's a large flat space on which to land, are engine failures always recoverable in a helicopter? I read on another site that an engine failure below 90 feet AGL or so is sure to result in a crash. I've heard of autorotation but don't know much about it, nor do I know much about helicopter flying in general. So, assuming a good pilot and flat terrain on which to land, how hard is it to land safely after a powerplant failure (everything else intact, just a total loss of power)?

In short - no.
To save typing out the whole theory, take a look at this:
Height-velocity diagram - Wikipedia, the free encyclopedia

Hi!

It depends, but, basically, with an engine failure, you autorotate to a safe landing area that is into the wind, and everyone walks away with no aircraft damage.

Obviously, there are variables.
Like:
If you are hovering, at, say, 100', then you are probably dead.
If there is an unsafe area, you are probably dead.\
Hovering at 5-20' or so, no problem.
All of the above also depends on the helicopter.
In the Huey, with an engine failure in a 5' hover, you could land safely, pick it back up to a 5' hover, rotate the helo 180 degrees, and then land safely AGAIN. I would guess that would not work in a Robinson R-22.

Landing the helo out of an autorotation is more difficult than landing a cessna-172 with an engine failure (more like a typical landing), but it is definitely do-able, as long as there are no negative factors (see above).

cliff
NBO

Depends on lots of variables - type of helicopter, airspeed, height, AUW, ability, wind, level of training etc. If all variables are favourable then there is a good chance of walking away from the arrival. If not then the outcome is debatable.

For more go to YT and search for "autorotation", there're plenty.

May I doubt that?

May I doubt that?

No, defenetly no.

A twin ( or more) engine helicopter, operated under CAT A limitation will NEVER crash if the pilot knows and applies the procedures depicted in the flignt manuel and mass limitations accordingly.

The engine failure may occurs in hover in ground effect, out of ground effect, during take off, in flight, nothing dramatic will happens and the pilot will land the helicopter safely either on an helipad or a runway.

Obviously, to reach such level of safety means mass reduction and appropriates procedures.

Dauphin N3 exemple: the N3 is CAT A approved on runway or unobstructed strip and helipad of at least 68 ft diameter. If the helipad is less than that, no CAT A available, thus, cat B flight and then, the safety during take off is no more guaranteed.

Well, the operative question for the OP is: "How many engines did you have when you started? 1? 2? 3?" In the latter two cases, unless the machine is old and in certain regimes, it's probably quite recoverable. Depends upon the performance characteristics of the aircraft in question. In the first case, it's not 'recoverable' if we mean continuing flight. But if we mean having the airframe be reusable, quite possibly.

Landing a helicopter out of an auto is (generally) a significantly briefer evolution and takes up a lot less real estate than landing an airplane of equivalent size. Difficulty depends a lot on what you've been trained to do. Most folks with a fair amount of Bell time can do a zero-speed auto entry from 100' and safely land the aircraft with a very low touchdown speed... in a Bell.

I'm often asked by non-pilots if it's "harder to fly a helicopter". My answer is: "not for me".

Just like airplanes, in general, the bigger the aircraft, the more challenging it is to get it all sorted out and put it on the ground without power without bending the machine or the blobs of protoplasm along for the ride. There are exceptions.

Many among us have autorotated numerous types made by numerous manufacturers to the ground. Some are easier than others. I expect most of us have preferences for aircraft we'd prefer to auto in an emergency if it came down to it.

In aviation, it is hard to answer any question that includes the words "always" or "never."

Not a heli pilot but just a few words on the HV diagram
they are composed for standard conditions so any deviation from the assumptions must be approach carefully and conservatively
the two worst areas are the low and slow and the very low and fast

Unfortunately, for me I'd have to spend big bucks for a good instructor but I've always wanted to learn those babies.

Very low and fast isn't bad - freeze collective briefly, cyclic climb, collective smartly down, auto attitude, flare, level, cushion, go to pub.

Aotw, you forgot the 360° turn!!!!!

Gomer (and others)
I have yet to see anyone who has had a real, unannounced engine failure from 100' not have damage to the helicopter and their body. There's a good reason for avoiding that area.
(I've probably done close to 100 demonstrations of the HV curve to budding test pilots and flight test engineers, as well as participated in a few real world HV curve demonstrations for certification, just to establish my bona-fides).
If you've convinced yourself through lots of training for autorotations that you can do a zero airspeed entry from 100' and got away with it, you're deluding yourself that when the real, unannounced failure happens that you can survive - the important part you're not thinking about is the surprise, it can't happen to me, this isn't true part of the real engine failure that deprives you of the very important two to three seconds that the training aspect doesn't consider. You're ready for the engine failure, know what's going to happen and are spring loaded to react to the first twitch of the throttle from the instructor.
and for those of you who think that you can get away with it from a 20' hover, much the same applies.
Everyone I've talked to who's had a real engine failure has said the same thing- the surprise factor caught them big time.
And just to round this out - when doing a zero airspeed entry from a high hover in a Jet Ranger (one of the more forgiving machines to do this in), it takes a minimum of 250-300 feet for the airspeed to start approaching something that will let you flare and have the rotor start to get back into the green. This is with a one second delay between rolling the throttle off and lowering the collective - a very short time.

To continue with Shawn's theme - the power loss following a real failure is likely to be more rapid than that resulting from simply rolling off the throttle. This is because the fuel scheduling of the AFCU/FADEC is set to prevent flame out (similarly a carburettor or fuel injection system prevents lean cut.)

So, the combination of anticipation and unrealistic power loss are giving a false sense of security.

False expectations
 

This instructor is passing on false expectations.
Just because Robinson euphamisticaly refer to this as the "avoid" curve, do not, for 1 second think this is actually really ok. (even you being a really good pilot and all)

Low speed / Low inertia rotor / Low Level ops will only ever end up in a world of hurt if the donkey really stops.
Frank would not be a happy man to see people deliberately operating and indeed training in this profile - and filming it for broadcast on You-tube no less!!:ugh:

Shawn, what you wrote about HV-curve for Vertical magazine would fit here perfectly, unfortunately the older issues are not available online, any chance to pass around the copyright, and have them here?

I have to put a sticker on the monitor reminding me to print all your articles :ok:

with respect - beg yours??

Well ahem, that jess depends on how low you really are.
it may well be much better of give the ol' heave ho stick a bit of a flick (then back down again) to position yon backside just a bit further from the ah-field prior to commencing yon flare.

sitting in a 100' hover, flat arsed, power on collective up, that is a real problem in an R22, not so much in some other types. forget the one second delay, you're in the wrong game if'n it takes you that long to sort it. not suggesting for one second that they are rcoverable without danage.

that 100' hover flight position is an indicator of lack of pilot acumen for sure.

rule of thumb is , when at 100' and very little if any A/S always try to plan to have the disc pointed at the ground, or at least the collective down quite aways, just zoomed up there, etc.
cheers tet

It's really a skill of power management when an engine failure occurs in a single-engined helicopter. Of course some machines have the edge (B206, B47 - providing you don't let high inertia blade rpm droop) but it doesn't mean lower inertia blades aren't manageable, for example, my CPL(H) flight school regularly trained autos down to 50' AGL in their singles (R22s among other types).

I keep reminding fellow helicopter pilots that engine failures are not a matter of "if" but a matter of "when". I have known many highly experienced pilots go through engine failures in their distinguished careers and the only common thread is the surprise and disbelief with the total denial "This isn't happening to me !".

Guess you haven't done those certain type of jobs then...