What happened
On May 18, 2004, at 14:25, a Socata TB 20, registration F-GSZF, was performing a flight from Rennes Aerodrome to Île-d'Yeu. The flight was intended as a recreational trip with two passengers. During the pre-flight inspection, the pilot discovered that the necessary radio headsets and microphone were missing from the aircraft. After spending approximately one hour searching for and retrieving equipment from the flying club's facilities, the pilot proceeded with the flight.
As the aircraft reached rotation speed during the takeoff roll, the nose gear suddenly retracted, causing the nose of the aircraft to drop. The propeller struck the runway surface, and the aircraft slid for approximately 100 meters before coming to a halt. The pilot noted that the landing gear control lever had been left in the "up" position. The incident resulted in damage to the propeller and the engine cowling.
The investigation
The investigation focused on why the nose gear retracted while the aircraft was still on the ground, despite the Socata TB 20 being equipped with a safety system designed to prevent accidental retraction. This system utilizes micro-switches on each main landing gear shock absorber; these switches cut power to the retraction actuator motor whenever the shock absorbers are compressed.
Testing in the workshop following the accident revealed no mechanical or electrical malfunctions in the landing gear kinematics or the position indicators. Investigators determined that as the aircraft reached a speed near takeoff velocity, the main gear shock absorbers extended, which neutralized the safety protection mechanism and allowed the retraction sequence to be triggered.