What happened
On June 19, 2015, a Robin DR 400-180, registration F-GMMN, departed from Cannes Mandelieu aerodrome to perform circuit patterns and local flight maneuvers. During the first circuit, air traffic control instructed the pilot to extend the downwind leg due to preceding traffic.
As the pilot transitioned to the base leg, the engine power was reduced to initiate a descent. While executing the final turn, the pilot attempted to increase power, but the engine RPM failed to respond. Despite switching to the main fuel tank and making multiple attempts to adjust the throttle, the engine power remained insufficient. Recognizing an engine failure, the pilot identified a clear area away from residential buildings and executed a forced landing in a field. During the landing sequence, the aircraft collided with the metal framework of a greenhouse obscured by vegetation.
The investigation
The investigation focused on the engine's failure to maintain power and the circumstances of the landing. Data from an onboard ISEI Safety Plane flight recorder revealed that the engine RPM had decreased to approximately 800 RPM shortly before the descent and failed to recover for the remainder of the flight.
Physical examination of the wreckage was significantly hindered by a fire. While investigators initially inspected the site, subsequent maintenance work performed by the flying club near the wreckage caused a fire that destroyed the aircraft's remains. Although the engine was recovered for specialized laboratory analysis, the fire damage prevented a definitive determination of the mechanical cause of the power loss.
Records indicated that the aircraft had undergone a 100-hour inspection just two days prior to the accident. This maintenance had addressed recent engine vibrations and included replacing the carburetor, magnetos, and magneto wiring, as well as repairing an oil leak. A successful ground test and a 25-minute test flight had been completed following these works.