AUTOGIRE.COM
04 Material damage: Machine destroyed Injuries: NO 1 DEAD
Accident Date: Summer 2000
Place: France
Summary: Crash following bird impact with the rotor

The instructor was conducting a test flight on a machine of his own design, a fully-enclosed two-seater. During flight, the machine tipped forwards, then exploded.

The initial discovery of the enquiry was that feathers were recovered on a rotor blade broken at about 2/3 of its length. The impact of the bird (possibly a crow) may have broken the leading edge of the composite rotor blade, air then may have penetrated the gap and then shattered the structure.

The craft then may have tipped to the front and a fuel spill caused the explosion of the machine. It's a fact that an autogyro rotor turns at more than 400 km/h, at the tip of the advancing blade, which could explane the violence of the impact.
It's difficult to say if an aluminium rotor in place of the composite part would have prevented the accident...

This autogyro accident is, as far as we know, unique in the world, seeing as how birds generally take care to avoid us, and our machines are noisy and slow enough.

To have this same accident, except with a 3 axis or weight-shift ultralight, might have the same consequences. All other aircraft are concerned, especially fighter and transport airplanes.

Modification of 23 November 2005:

In fact, it's true that the bird was the initiating element of this accident, but the rotor was not by itself the cause...

Because, I've read a letter from the BEA [Bureau Enquêtes Accidents, French accident investigation board] that completely exonerates the rotor, which says that this did not break in flight, but on the ground, when the machine fell.

To understand this, it's enough to look at the bend in the blade produced by bearing the weight of the machine at the moment of the crash. In addition, this blade was found in proximity to the site of the crash, while if it had broken in flight it would have been found further away...Other scientific analyses have been carried out on samples, which have confirmed this.

The deduced thesis:

The rotor did hit a bird: the traces of bird blood, and the video, attest to that. ainsi que la vidéo. The blade transmitted vibrations to the tubular mast of the craft. This last was very particular, and the pilot (its inventor) planned to apply for a patent for this novel system.

It actually comprised a mast of two parts, joined by a nylon block which isolated the natural vibrations of the rotor.

The whole thing was not secured by a small link like the first machine that was created by the inventor, and the system was definitely lacking in rigidity.

So, after the impact of the bird, lthe junction between the two parts of the mast was no longer able to isolate the vibrations, and the pilot was not able to firmly hold the stick and attenuate the oscillations. The aircraft tumbled forward and caught fire

Another accident of this type has been described in the American forum:

http://www.rotaryforum.com/forum/showthread.php?t=6353&highlight=eagle+strike

Hervé TERRASSON

 


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