R22 down at Cannes

[n5296s]

An R22 crashed into the sea just off Cannes yesterday afternoon, killing the instructor and student on board. I'd watched it take off a few minutes earlier. An eye-witness, who happened to be a pilot, said clearly that the rotor was not turning. So in all probability classic R22 rotor stall. Very sad.

https://aviation-safety.net/wikibase/349815

[Agile]

R22 from greenbee helicopter, they are really good bunch. They come from the training branch of former azur helicopter. After it got acquired by blade.

[malabo]

So in all probability classic R22 rotor stall.

Is this a thing, or rote pprune Robbie bashing?

Trained on 22, instructed 1000 hrs, flew professionally 40 years, never heard of it.

[RVDT]

It's a thing - not many survivors around to talk about it.

Robinson Safety Notice SN-24 (https://robinsonheli.com/wp-content/uploads/2015/12/rhc_sn24.pdf)

[n5296s]

Is this a thing, or rote pprune Robbie bashing?

No, routine R22 bashing. Practically all my helicopter time is on R44s, which are very nice flying machines - despised primarily by those whose turbine flying time is paid for by someone else.

But when the engine stops, you literally have 1.5 seconds to drop the collective on an R22 - including the time it takes you to realise and react. When people talk about EFATO training in fixed-wing, they assume (iirc) 3 seconds to even realise something has gone wrong. The truth can evidently be less or nobody would have survived an R22 engine failure. But there have nevertheless been numerous fatals when people (including, as in this case, experienced instructors) didn't get the collective down fast enough.

[hargreaves99]

I seem to remember reading somewhere that an actual "real engine failure" in an R22 is extremely rare, with only a handful having ever occurred. Most "engine failures" are, in reality fuel exhaustion or carb heat issues (ie pilot error).

[Robbiee]

"Classic" R22 rotor stall is apt, as that was a problem waaaaaaay back when the machine was new to the world. Nowadays, you'd have to reeeeally be distracted to let one stall,... especially at sea level.

[Hughes500]

Er Hargreaves they are still engine failures though ! So need the same actions

[n5296s]

Nowadays, you'd have to reeeeally be distracted to let one stall

I don't follow. Have they made seconds longer since 1985? You still have <2 seconds to realise what has happened, get your hand back on the collective if you happen to be tuning radios etc, and get it down. Maybe you're more aware of it now, but thats all.

​​​​​​​In this case there was an experienced instructor with loads of R22 time on board. Didn't help.

[Agile]

I understand they had just taken off. I trained out of Cannes a bit (type rating). Heading toward the sea is normal to transition either east or west, (I forgot) to reach the training areas north of the airport. Do you recon a training event gone bad or an unexpected failure?

[n5296s]

Helicopters use 22/04 (04 that day) with a traffic pattern out over the sea, so their flight was normal pattern work. If they were practising autos, they wouldn't have started there. And the instructor would have had her hand on the collective spring-loaded to push in case the student wasn't quick enough. So the most likely case is some kind of engine failure.

[atakacs]

It's a thing - not many survivors around to talk about it.

Robinson Safety Notice SN-24 (https://robinsonheli.com/wp-content/uploads/2015/12/rhc_sn24.pdf)

Bit of a tangent but really love the way this note is written... not something you would see nowadays.

[Robbiee]

I don't follow. Have they made seconds longer since 1985? You still have <2 seconds to realise what has happened, get your hand back on the collective if you happen to be tuning radios etc, and get it down. Maybe you're more aware of it now, but thats all.

In this case there was an experienced instructor with loads of R22 time on board. Didn't help.

If you're saying that the accident was the result of a sudden engine failure, sure.

If you're saying the accident was the result of "classic rotor stall" then that is an engine still running accident, which generally requires the pilot to be "not paying attention" to happen.


Plus, if it was a sudden engine failure, the problem isn't so much getting the collective down in time (as we are trained diligently for that) but if the student raised the collective instead, THAT could most certainly cause the blades to stop!

​​​​​​​,...and the R22 came out in '79.

[[email protected]]

You can only get the rotor to stall if the Nr is very low - this can be power off (and failing to lower the collective following a loss of power) - or power on (massive overpitching).

In a circuit pattern it is most likely to be a practice (or real) engine failure with late intervention to lower the lever.

[RVDT]

You can only get the rotor to stall if the Nr is very low - this can be power off (and failing to lower the collective following a loss of power) - or power on (massive overpitching).

In a circuit pattern it is most likely to be a practice (or real) engine failure with late intervention to lower the lever.

And it is highly unlikely there will be a requirement for a post-flight debrief.

[henra]

Trained on 22, instructed 1000 hrs, flew professionally 40 years, never heard of it.
Never heard about it? Maybe you should start reading accident reports. Can be very enlightening...

[Agile]

You can only get the rotor to stall if the Nr is very lowYes it is that simple, let us not invent new wording around it, or assign to anything special to the R22.

The thing to remember is that lift is a function of velocity squared (L = 1/2 ρ V2 × S × CL) for every 20% RRPM lost you lose 40% lift.
Thus the problem with low inertia rotors, the speed at which you go into trouble is also squared.

fast RRPM loose will give you the feeling that the seat is falling from under you and if you instinctively raise the collective thinking it’s a downdraft, you are done!
you can call that a stall if you want, although this is more a fixed wing term.

Also I would say that recovering a lot of RRPM that you lost entering late into the auto in the R22 can be a quite a trip.
I did that ab initio early in my training, waited the whole glide down with the lever fully limit down looking mostly at the RRPM gauge.
It did make it to the green again as it was time to flare not a second too early, good wake call that day.

[212man]

for every 20% RRPM lost you lose 40% lift.

Not quite accurate - using that logic a 30% reduction would equate to 90% loss and 40%…..well, you get the idea.

Base it on the actual Nr, so compared to 100% Nr the lift (purely as a function of Nr, and not CL with the varying pitch and AoA):

80% = 64%
60% = 36%
40% = 16%

But the loss is exponential (by definition) and, so, dramatic!

[Robbiee]

,...or assign to anything special to the R22.


You mean,...like a Special Federal Aviation Regulation. :}

[Casper24]

You still have <2 seconds to realise what has happened, get your hand back on the collective if you happen to be tuning radios etc, and get it down.

You are correct if you aim to do nothing but lower the lever however remember that when in forward flight you can trade airspeed for RRPM by flaring. In fact in the cruise it is possible to not lower the lever for some seconds even in a low inertia system with the steady application of aft cyclic should your left hand be busy as you describe and not on the collective. We sadly do not seem to teach and stress the importance of how to manage the energy stored in ones rotor to students as much as we did in the past.

[hargreaves99]

https://www.youtube.com/watch?v=RJ8SAnwxD6I

Energy management is taught a lot more in the FAA system due to the SFAR 73 requirement, it's barely mentioned in the CAA PPL Syllabus.

[Robbiee]

https://www.youtube.com/watch?v=RJ8SAnwxD6I

Energy management is taught a lot more in the FAA system due to the SFAR 73 requirement, it's barely mentioned in the CAA PPL Syllabus.

Well, its been around since the mid/late 90's, so, there's really no excuse to not adopt the FAA's training syllabus if you're going to use our choppers.

[Agile]

In fact in the cruise it is possible to not lower the lever for some seconds even in a low inertia system with the steady application of aft cyclic
Yes it is a good exercise to train yourself, it takes a bit of finess to make the best of it, but one can easily get an extra 5 sec of no Nr change provided you are going fast.
you could also use that technique to get the Nr back in the green quick with a much more agressive flare, even if you are short on speed.

In that case, they were empty handed, taking off, I assume speed still arround 50knots +, altitude could not be much more than 500ft, and land was behind.

[jimjim1]

I don't follow. Have they made seconds longer since 1985?

Not that I have noticed. However Robinson added rotor tip weights to increase the rotor inertia and extend the time that a pilot has available to respond to an engine failure.

Change was made before about 1991 and as I understand it older aircraft were modified. Even with the weights time is short.