as350b3 tail rotor blade problem

[tigerpic]

does anybody have text or pictures concerning the separation problem that as occured along the trailing edge of the blades? i'd like to learn more about it. accidents/incident info would be very helpful.


cheers,

huck finn

[rotormatic]

See:

http://www1.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/cbe9fa2539ba644786256b5d0055dfcc?OpenDocument&ExpandSection=2#_Section2

[Helinut]

I believe that the AD action was initiated after a tail rotor blade failure in a very new AS350B3 in the UK. Only the prompt landing of the aircraft prevented the "incident" from having a much more serious outcome.

I did hear some suggestions that further investigations "unearthed" some more similar incidents in Europe, but I have no details of these.

[Sqpilot]

The facts of the incident referred to, are as follows.

About 15nm SW of Lyon France on Oct 18 2001. AS350B3 with 148 hours since new. No crack seen on daily inspection, and none seen by maintenance organisation 8 hours before during a check.

Sudden huge vibration so bad that I could hardly hold the controls. There was no doubt that a landing was needed asap, and fortunately I was over a small flat field in a hilly, wooded and wire hostile area. Landed after about 60 - 70 seconds of the worsening vibration. Got out to find about 50 - 60% of the effective area of one tail rotor blade missing, having failed in a straight line from a crack at the trailing edge, trim tab join as per the faa ad. Of the 4 bolts holding the tail rotor gear box to the tail boom, 1 large rear one was missing, having broken the locking wire and unscrewed itself, one front support strap was broken, the other front strap was in the process of breaking, and the final large rear bolt had broken the locking wire and was half way undone. I would guess I had about another 10 - 15 seconds before the TRGB came off completely. There was flexing damage to the lower tail fin, and several missing rivets from it. Also flexing and ripple damage to one of the stabilisers. The helicopter was in the process of breaking up.

Had I been higher that the approx 1300 feet I was at, or had it happened two hours later when I would have been at 5000 ft over the Med sea, I wouldn't be typing this.

Subsequently Eurocopter told us there had been 31 instances of cracks in this blade location, with this being the only case of blade seperation. The next most serious was a crack of about 4 inches or so. Whilst some French operators seemed to know about the problem, the UK agents said they did not, as there had been no SB or AD.

Eurocopter have, as far as I know, so far provided a new tail rotor blade under warrenty!

I was very lucky to walk away from this potentially fatal failure. And yes, I have some fairly dramatic pictures of the blade etc.

So do check your TR blades carefully before every flight, especially, in my opinion, on the AS350 B3. The AS355N apparently uses the same TR blade.