What happened
On 2/6/2018, a GAZ’AILE 2 microlight, registration 64AAC, departed Oloron-Herrère aerodrome for a local flight. During the return phase of the flight, while descending at approximately 1,500 ft, the engine shut down. The pilot attempted to glide toward the aerodrome, which was roughly 4 km away; however, the aircraft's glide performance was insufficient to reach the runway.
As the aircraft approached the threshold of runway 07, the pilot attempted a forced landing in a field. The aircraft struck the ground in the commune of Gurmençon, approximately 1 km from the aerodrome, resulting in the fatal injury of the pilot and the destruction of the aircraft.
The investigation
The BEA examined the wreckage and the aircraft's iEFIS Explorer Lite flight computer. The investigation focused on the propulsion system, specifically the PSA Peugeot 42 KW diesel engine and the reduction gearbox. Investigators analyzed the three-blade composite propeller, which showed evidence of bending failure at the roots and along one blade.
Data extracted from the flight computer confirmed that the engine shutdown occurred at 20:16:44, and the aircraft continued to glide for over one minute before impact. The investigation also reviewed the fuel system, finding no evidence of fuel exhaustion or contamination, and examined the topography of the surrounding area to assess landing options.
Findings
Technical examinations of the engine revealed no malfunction that would cause an uncommanded shutdown. However, investigators identified damage within the reduction gearbox. Specifically, one of the four screws connecting the flexible coupling to the engine shaft had failed due to fatigue cracking and subsequent overload. Additionally, friction marks indicated an interaction between the gearbox structure and the engine-side pinion. This mechanical issue likely produced significant vibrations or noises, which may have prompted the pilot to intentionally shut down the engine.
Regarding the flight path, the investigation noted that the pilot's decision to attempt a return to the aerodrome was likely influenced by having clear visual references to the destination. The pilot's desire to reach the aerodrome rather than landing immediately in a nearby field contributed to the outcome.