EoN Olympia 460 wing fails on winch climb after spar corrosion

A pilot was fatally injured when the right wing of a 1962-built EoN Olympia 460 failed in the winch climb at ~200 m AGL; airframe destroyed, break-up too low for parachute escape. Examination found long-term intercrystalline corrosion in the alloy straps bonded to the wooden spar booms, reducing right-wing tensile strength by ~20%. The winch weak link — rated 500 kg — was two identical 500 kg strips in parallel rather than one with an elongated-hole partner, and failed at 987 kg, transmitting excessive launch loads. Witnesses had reported a faster-than-normal launch with pitch oscillations and abnormal wing flex just before the failure.

1. Winch launch climb: This was the day's second winch launch by the same pilot and glider; witnesses described it as faster and less steep than the day's other launches, in a strong wind gradient.
2. Long-term spar corrosion: Intercrystalline corrosion had developed over years in the aluminium straps bonded to the right wing's spar, costing about 20% of tensile capacity, hidden under intact-looking paint.
3. Over-strong weak link assembly: The cable's weak link was meant to fail at 500 kg using one load-bearing strip and a standby; here both were identical strips sharing the load, and the pair later failed at 987 kg.
4. Fast launch loads: At about 200 m AGL the glider was seen to speed up and reduce climb angle, consistent with launch loads exceeding what a correct weak link would have allowed.
5. Pitch oscillations and wing flex: Still nose-high and on the cable, the glider developed several rapid pitch oscillations (one witness estimated ~15°) and the wings flexed an abnormally large amount.
6. Right wing spar failure: The airbrakes cycled briefly as the right wing's main spar failed in compression on the upper boom and tension on the lower; the wing pivoted upward and rearward, and the cable separated.
7. Break-up too low for bailout: The wreckage fell from too low for the pilot to escape by parachute; airframe destroyed, pilot fatally injured.