Défaillance structurelle de l'EoN Olympia 460 lors d'un lancement par treuil à l'aérodrome de Sleighford

Le 13 juillet 1996, un EoN Olympia 460 a subi une défaillance structurelle fatale lors d'un lancement par treuil à l'aérodrome de Sleighford, Staffordshire. Le planeur, piloté par une personne ayant environ 50 heures de vol, a subi une défaillance catastrophique de l'aile peu après le décollage. Des témoins ont observé des oscillations de tangage inhabituelles et une flexion des ailes avant que l'aile droite ne cède. L'appareil a été détruit et le pilote n'a pas survécu. Les enquêtes ultérieures ont révélé une corrosion significative dans le longeron de l'aile, conduisant à la défaillance.

1. Winch launch climb: The glider began a winch launch from Sleighford Airfield, quickly becoming airborne and adopting the climb attitude in what witnesses considered a faster, less steep than normal launch.
2. Degraded wing spar: Long-term corrosion and bond failure in the right wing spar root alloy strap assemblies had significantly reduced the structural strength of the spar.
3. Over-strong weak link: The winch cable weak link assembly, using two identical 500 kg links in parallel, was found to fail at about 987 kg, allowing excessive launch loads to be transmitted to the airframe.
4. Excessive launch loading: During the winch climb at around 600–700 feet, the combination of a fast launch and over-strong weak link likely imposed loads that exceeded the degraded right wing spar’s strength.
5. Pitch oscillations and flex: While still on the cable in a nose-high attitude, the glider developed relatively rapid pitch oscillations and witnesses observed abnormal wing flexing.
6. Right wing structural failure: As the airbrakes briefly deployed and then deployed again, the right wing main spar failed, the wing pivoted upwards and rearwards with debris released, and the cable separated from the glider.
7. Crash - fatal: With the right wing failed at low altitude, the glider broke up and impacted the ground before the pilot could escape by parachute, fatally injuring the pilot and destroying the aircraft.