Dauphan Crash
 

Just seen a foreign (Middle East?) Dauphan spinning out of control and crashing while in the hover on the BBC news. One killed, a number injured. Engine failure was mentioned. Looked suspiciously like "fenestron stall" - been there done that.

Yep, just seen that and discused it with colleagues.

I thought 'fenestron stall' up to the ditching, but the subsequent pull up from the water(last in a series of "why did I do that" moves) tends to refute that. On the other hand, why was the fenestrom still turning? Most footage I have seen of tail rotor failure shows the tail rotor stopped during the 'spinning'.

Good news is that the co-pilot escaped, but is in a coma, the rest are not serious. Wouldn't have liked to have been the diver though; jumped clear, only to have a spinning Dauphin (only one a in Dauphin) land on top of him.

Question; why did the co-pilot end up in a coma when he was on the 'air side' of the sinking a/c, as opposed to the Captain, who was under the water through most of the sinking?

It was a Taiwanese a/c demonstrating their wonderful SAR capabilities to the media, hence the clear footage.

Remind me not to need rescuing in Taiwan!

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Another day in paradise

[This message has been edited by 212man (edited 06 September 2000).]

I believe it was the Taiwan Police
in an exercise to prove their ability.
I'm not a Dauphin driver, but it looked
a little tailrotor-ish to me.

Yes I knew the spelling was dodgy. Their is no drive failure for "fenstron stall", otherwise known as loss of tail rotor effectiveness. There's been a few cases with AAC gazelles(including me) over the years. Usually attributed to handling errors. The best one was a basic student at Wallop about 91/92 in the middle of a packed dispersal. He managed to miss everything.
:)

The video can be seen at http://news.bbc.co.uk/hi/english/world/default.stm

Appears the pilot has put it in the water inadvertently, the fenestron blades or tail rotor driveshaft has been damged with the water impact and when the pilot has pulled it back out of the water he has no tail rotor control hence the spin. I don't think engine failure was responsible for the accident because he managed to initially pull the aircraft out of the river even though it has taken on water (open rear door)

Mighty Gem,

I though I would correct you by reminding you that there is no such thing as "fenestron stall". It is in fact as you stated a "loss of tail rotor authority".

This was determined during a RN trial in France using a RN Gazelle and "beefer who had been there and done that" in the early to mid 90s. What it proved was that the fenestron does not in fact stall and that recovery action is always available - what the pilot has to do is take that action.

The AAC adopted the recovery action following these trials although the myth about "fenestron stall" undoubtedly persists

From the brief clip I say on TV I would offer the following. Tail rotor servo or No 1 hydraulic failure. This causes yaw pedals to become very heavy, hence initial slow yaw to left followed by inadvertant entry into water. Engine failure unlikely as a single engined Dauphin would not rise out of the water but a twin engined one with max power applied would behave as seen as it needs the legs of a weightlifter to combat the yaw produced at max power with no servo assistance so the helio rotates as seen. Sorry to hear one of the pilots didn't make it.

Mighty gem,
I was not saying that the fenestrom stall was a result of drive failure; I was saying that the initial impression that that might have been the cause was dispelled by the subsequent pull up. ie If the initial problem was loss of TRE, this would have been solved by the forced stopping of rotation by the impact with the wet stuff.

I was puzzled by the fact that the fenestrom ws still rotating during the subsequent loss of control, which lends credence to the servo answers. However, surely part of the certification is that such failures are controllable by the average line joe, and do not require super-human strength to counteract?

I guess that if we ditch in a Dauphin we don't need to wait 7 seconds for the rotors to stop turning? Nice design touch of the frogs that; frangible main rotors.

If you watch the newsclips real close, you'll see that the TR (fenestron) entered the water. After that, you're on your own.-CY

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*deep inhale* I LOVE the smell of jet-a in the morning..

How about; handling pilot detects tail rotor failure and precipitiously ditches a/c, non-handling pilot thinks what the f*** and yanks collective up.

I also agree that sticking the fenestrom in the water might have caused the subsequent problems, the stall theory could still be right, except I think they were probably into wind during the approach to the boat.

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Another day in paradise

FenestroN, 212 man, FenestroN.
And when a fenestron 'stalls', which it doesn't, the thirteen tail rotor 'blades' are rotating at their normal rpm. The pitch of them however contributes to a loss of tail rotor authority.

Sad day. Having played back the video footage of this accident I am amazed and rather shocked by the following flight safety issues:

The aircraft does not appear to be fitted with floatation gear.

The three rear crew, including the abseiler, were not wearing helmets - was the fatally injured co-pilot, I wonder? (Baseball caps don't offer much protection, even falling off a bike).

The three rear crew did not appear to be wearing lifejackets.

At least one of the rear crew appears to be operating whilst completely un-restrained by any sort of harness.

I was very surprised that the aircraft appeared to be deliberately lifted off again after its water landing.

I for one would like to read the findings of the accident report on this one...

Let us hope that relevant lessons will be learned by those that matter.

Thanks bovine for the spelling check; not a word I use much. As for the 'rotating' and 'stall' stuff: I was mentioning them as separate issues ie if it was a drive failure why was the fenestron still turning? and if a loss of TRE (if the blade pitch angle is such that the flow separates and results in loss of TRE, is that not a form of stall?) why did that persist after the ditching, and indeed become worse?

I agree with the last remarks, there seems to have been a bit to much emphasis on looking like a "cool" outfit rather than operating with safety in mind. If they'd been out at sea the casualties may have been much worse (drowning).

I suspect that even with the publicity shy Chinese/Taiwanese authorities, Eurocopter will be keen to get to the bottom of this, and release the findings to counteract concerns after such a widely seen accident.



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Another day in paradise

IMHO I believe that the HP dealt with a fenestron drive failure very well initially, unfortunately they didn't chop the engines and after the cushion they lifted again and spun.

Fenestron Stall was called 'Yaw Divergence' when I went thru Shawbury. If I remember correctly you needed wind from a certain direction and to then move the tail thru it. The pictures don't show the pilot yawing the tail, it just seems to go. I may be wrong and frequently am, ask anyone who knows me.

A tragic accident and unfortunate timing(if there can be a good time for such a thing)

Perhaps there was more to this than was shown on UK TV. I saw the incident on (I think) a German channel. The sequence of events which does not seem to be described above was like this.

Dauphin hovering over water at 20 - 30 feet, swimmer in the door apparently waiting to abseil down a rope, but the rope had turned into a bunch of bastards and no 2 crewie was trying to unravel the hopeless mess.

Cut to shot of helo with said crew still in the door plop firmly into the ogwash on a level keel with no yaw apparent and a bit tail down - the fenestron was half submerged for a second or so, water almost at cabin floor level.

Helo immediately and abruptly pulls up out of water, I looked but could see no sign of fenestron blades either present or absent. Helo immediately began to yaw, after 2 turns or so swimmer has had enough and jumps, a second or so later pilot decides hes had enough too and ditches, clearly on top of swimmer. Two pwople seen scrambling clear of cabin as it sinks.

It looked to me like an inadvertent ditching which wrecked the fenestron with end result inevitable after lifting off again.

I can just picture the pilot looking over his shoulder in frustration to see what the crew were up to and let it just sink down into the river, then Oh **** O Dear and pull up by reflex. Look over your left shoulder and which way does the collective move???

http://www.pprune.org/ubb/NonCGI/frown.gif http://www.pprune.org/ubb/NonCGI/frown.gif http://www.pprune.org/ubb/NonCGI/frown.gif

Piston B,

Looks like you missed the initial increasing yaw to the left through 90 degrees and the slight nose up / down pitching while the aircraft descended into the water.

One other plausible theory is this could have been an engine fail / overpitch situation leading to a loss of Nr and therefore reduction of yaw control.

Also, I would say that the conker lost his footing rather than jumped. He was still fastened to the aircraft by the rope as it ditched and was extremely lucky to escape.

Hopefully they will get professional advice before trying this type of op again!

general discussion at Sy is that the most likely route was a single engine failure (the Daupin is notorious for poor single-engine performance). The subsequent reduction in Tr rpm (as evident from the high coning angle of the main disc) would cause yaw problems. This (to my mind) could have led to fenestron stall - I don't care what the pundits say, I reckon these devices CAN stall. All the bull!!!! from the AAC years ago about pilot error do not ring true!

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Darned if I can find that video - anyone able to provide a link?

PB, the video is at:
http://news.bbc.co.uk/olmedia/910000...yes1300_vi.ram