What happened
On September 4, 2007, a privately operated SOCATA TBM 700, registration F-GTJM, was performing a flight departure from Paris Le Bourget airport. During the landing gear retraction sequence following takeoff from runway 09, the pilot observed an abnormal indication: the red warning light began flashing, and the green light indicating the nose gear was down and locked remained illuminated.
Following this indication, the pilot decided to perform a turnaround to land on runway 03. During the gear extension process, the two green lights for the main landing gear illuminated, but the red warning light remained steady. After receiving confirmation from air traffic control that the nose gear appeared to be extended, the pilot chose not to execute the manual gear extension emergency procedure. During the taxiing phase of the landing, the nose gear retracted, causing the aircraft to strike the ground. The incident resulted in damage to the propeller, engine cowling, and nose gear doors.
The investigation
The investigation focused on the landing gear indication system and the pilot's decision-making process. Investigators examined the aircraft's hydraulic and electrical signaling components. Ground tests revealed that a faulty nose gear locking switch was causing the green light to remain illuminated even when the gear was in the process of retracting. This fault caused the red warning light to remain continuously lit.
Furthermore, the investigation found that during the gear extension sequence, the hydraulic pump received a signal indicating all three gears were locked, causing the pump to stop prematurely while the nose gear was still unsecured.
Findings
- The primary cause of the accident was the pilot's decision not to perform the manual gear extension procedure following an incorrect analysis of the warning lights.
- The pilot had experienced similar continuous red warning light indications on this specific aircraft approximately two years prior. On those previous occasions, a mechanic had informed the pilot that the light was a false indication and did not represent a true gear position anomaly.
- The pilot was unaware that the manufacturer had since implemented a system modification to resolve this specific issue.
- Because the pilot believed the current warning was the same intermittent fault experienced in the past, he did not initiate the emergency manual extension, leading to the nose gear collapse during taxi.