What happened
On 29 May 2022, a SOCATA Rallye 100ST, registration F-BUNQ, was returning to Besançon-La Vèze aerodrome following a cross-country flight. While flying the base leg for runway 23 at approximately 2,300 feet, the pilot experienced a reduction in engine power followed by a complete engine shutdown.
The pilot attempted the emergency restart procedure twice, including switching fuel tanks and manipulating the carburettor heat, but the engine failed to restart. To avoid flying over a built-up area, the pilot initially identified a field to the left for an emergency landing. However, realizing the aircraft was too high for that specific location, the pilot selected an alternative field further away. During the landing, the aircraft struck a bank, causing the nose gear and right main landing gear to fail, and the plane came to a rest on its nose.
The investigation
The investigation focused on the engine's performance and the aircraft's mechanical state. Investigators examined the engine, including the magnetos, spark plugs, and carburettor, as well as the fuel system and fuel samples. The engine was found to rotate freely without internal friction, and the carburettor was leak-tight. Analysis of the AVGAS 100LL fuel showed no anomalies. The investigation also reviewed the aircraft's maintenance history, noting that a 50-hour inspection had been completed 19 flight hours prior to the accident.
Findings
- The pilot and one passenger sustained injuries.
- The engine shutdown was the primary event, though the specific cause for the loss of power could not be determined.
- The aircraft sustained significant damage, specifically the failure of the nose and right main landing gear upon impact with a bank.
- The pilot's decision-making regarding the landing site was influenced by the need to avoid residential areas and the aircraft's glide path altitude.