Idiot Gazelle crash report released

[LOOSE NUT]

If anyone is interested AAIB have released incident report of Gazelle crash in July on their website. www.aaib.dft.gov.uk
I take full responsibility and will take all criticism leveled at me.

LOOSE NUT :(

[handyandyuk]

Could have been worse....:(

At least you're still here and able to see what went wrong.

[hihover]

Loose Nut -

Don't be too hard on yourself, and don't invite criticism, you were bitten by one of the few Gazelle "bites". Only those who have found themselves in that situation can appreciate how quickly concern develops into terror upon finding themselves in a helicopter over which they have little control and are within a few feet of the ground.

I have about 4000 hours in the Gazelle and have enjoyed every minute, even though some of them were scary.

I was prompted to investigate the phenomenon of loss of tail rotor control or effectiveness/fenestron stall back in 1987 when I was a passenger in the rear of a Gazelle which completed 3 full 360s in about 5 seconds, before the pilot dumped it on the ground heavily.

The incident happened at the end of a training flight. I won't bore you with the details, but suffice to say, the pilot's lead feet on the pedals started the incident and when he found himself in a high rate of left yaw, he applied full right pedal. I concluded, after subsequent consideration and research, that his sudden application of full right pedal stalled the fenestron and the aircraft simply continued to yaw under the influence of the torque reaction.

Aerospatiale joined in the investigation and conducted a series of tests from which they concluded that, full application of right pedal is the corrective action required, however, it may take some time for tail rotor effectiveness to re-establish.

This may work for their test pilot in a controlled situation where he was ready for the stall, but for the pilot who is caught unawares, it is a huge drama. The yaw in our case was exacerbated by the pilot applying collective pitch to get away from the ground (his natural reaction) and the aircraft then started pitching up and down, possibly as a result of increased downwash on the horizontal stabiliser and pilot cyclic input.

The bottom line was, it happened to this experienced pilot, it happened unbelieveably quickly, and he was not aware of what was going on. We all immediately suspected a tail rotor driveshaft failure.

The lessons that I pulled out of it were;

1. There is a tail rotor phenomenon associated with the Gazelle that requires some discussion/instruction (not practical) with every Gazelle pilot.

2. Any manipulation of the collective or pedals has to be gentle (as advertised), to save any requirement for large corrective pedal inputs that may cause further problems.

3. It is more practical to discard and replace fully soiled underwear, rather than launder them.


The Gazelle is a great aircraft, try not to be put off.

I am glad to hear that you all walked away from the accident.

[PPRUNE FAN#1]

First of all, jolly good job that both you and your wife were not seriously injured in what was a very bad crash. Please don't be too hard on yourselves. Accidents can and do happen to everyone.

Lessons learnt? Plenty!

I've only flown a Gazelle once, over twenty years ago. I picked it up into a hover, then started a left pedal turn. The other pilot immediately over-rode me and told me to make the turn to the right. Although he did not have time to fully explain why, I now understand. And now that we're more educated as to the interaction between the main rotor and fenestron, we can all be better prepared to deal with the handling peculiarities of this model. It is noteworthy that Eurocopter has markedly changed the fenestron design on later models.

I have only one gentle observation to make, and hope you don't take offense. The accident report made reference to "witness marks" on the ground, made by your helicopter at its initial lift-off point. Many helo pilots are in the habit of allowing the ship to come off the ground with some yaw, assuming that they'll get it stabilised once airborne.

This accident reinforces why it's so important in the Gazelle to get the yaw-trim correct as the ship is light on the skids and before breaking ground. It is not easy, it takes real work, and is often a challenge for even us experienced, commercial pilots when the wind is at its most disadvantageous. So I do not fault your wife.

Again, don't beat yourselves up over this. I do hope that this accident has not put you two off of flying, nor off Gazelles. Wonderful ship!

[LOOSE NUT]

PF#1

Thanks for your reply and everyone else who has taken time to respond. I think you have read an earlier report but one which sounds as if the same problem occurred so your comments are also relevent to me. Luckily my wife was not with me that day but everyone who was has been very supportive and wish me to continue as pic.

many thanks
LOOSE NUT

[PPRUNE FAN#1]

Loose Nut:
Thanks for your reply and everyone else who has taken time to respond. I think you have read an earlier report but one which sounds as if the same problem occurred so your comments are also relevent to me. Luckily my wife was not with me that day but everyone who was has been very supportive and wish me to continue as pic.

Sorry, mate! I looked up the site and a Gazelle crash in July and just assumed that G-HAVA was yours. Which one should I have been looking at?

[TwinHueyMan]

I believe this (http://www.aaib.dft.gov.uk/bulletin/oct02/gbzos.htm) is the report in question.

Everyone gets confused, and I can understand your situation even more by the fact that you were in a "reverse" rotating helicopter that has a tendancy to start going yaw-squirly with a very severe control movment required to stop it. You and your passengers got out alive, and that's all that matters.

I wish you better luck in the future!

Mike

[Thomas coupling]

Loose Nut: takes balls to admit that in public...all experiences are positive ones. Strikes me you're man enough to absorb this little hiccup in your life...good luck to you.

[MightyGem]

Loose Nut, been there, done that , got away with it. Just! Scariest thing that's ever happened to me in a helicopter:eek:

[SASless]

Have heard from reliable sources....even monkeys fall out of trees! I would love to have access to all of the accident reports ever written and also do confidential interviews of the pilots to see how much truth was lost between their mishap and the final telling of the story. It is a very rare case when a man steps forward and tells the God's honest truth....integrity is not situational and strikes me there is at least one honest man in the house. Flying becomes rather exciting when one runs out of altitude, airspeed, control authority, experience, and ideas simultaneously....you aren't the first....and surely you shall not be the last. To look on the bright side of all this....with enough wine....any dinner party could be the better for a proper telling of this story! A "There I was...." story if there ever was one!;)

[Whirlybird]

Loose Nut,

I've never flown a gazelle, but it sounds like something anyone could have done. I don't know about you, but flying Russian helicopters recently, which all have clockwise rotating rotors, I found it incredibly hard to use my right foot enough. Full right pedal was just such an unnatural thing to do; almost like walking backwards or something. I can easily see that in an emergency, when you have to react instantly...

No doubt someone will say you're an idiot; someone always does; some people love criticising others. But not anyone who's ever been in an emergency situation, in a helicopter in which they had a limited number of hours. So don't listen to those who don't understand and who should therefore shut up; learn from it and go on...as you have or you wouldn't have posted this thread.

[Woss goin on..?]

Loose Nut

Firstly, glad your all ok after this incident.

A question....your aircraft is on a Permit to Fly for which I understand the only persons allowed on board are 'crew'. Given that there were 4 on board, is there a way in which the crew only restriction can be relaxed?

No motive or accusation here, just interest, as colleagues and I have been discussing this issue of late.

[Paul McKeksdown]

Firstly, as with all the other mails, it's good to see that your okay.

I have also flown the Gazelle and came very close to the phenonmenm (?) know at the time as 'Fenestron Stall'. This was investigated by sending aircraft to Eurocopter in France where the Test pilots span them round in small circles for a couple of days.

The huge amount of data they collected boiled down to the fact that the Fenestron was not 'Stalled' but had reversed airflow around the tips in spite of the shroud containing the blades. These conditions were most likely to be reached during:
1. A rapid or sudden demand for a left turn.
2. Wind from the right.

The onset is rapid and indeed very scary! Especially for a Gazelle beginner. Subsequently I have flown a large variety of helos and can say that the Gazelle rates up there as No.2 for fun factor!

Flying is a risky business and it is only through work, and the disemmination of information and experience that we can continue to make it safer.

Good luck and have many more hours fun flying the Gazelle.

[Fortyodd]

Loose Nut:
In common with Mighty Gem, I've been there, done that, got away with it and carried out the required changed of underpants. You are not the first and you won't be the last. The Gazelle does not have that many vices - you simply discovered the worst of them early on. Sincerely hope it hasn't put you off flying.