What happened
On March 20, 2011, a Robin DR315, registration F-BRTK, was conducting local flight training at the Castres Mazamet aerodrome. Following a flight with an instructor, the student pilot was cleared to perform solo circuit patterns. After taxiing toward runway 32, the student attempted a left turn on the turnaround pad. During this maneuver, the student applied the right rudder pedal to stop the aircraft's rotation, but found the braking action to be ineffective at stopping the turn. Although the aircraft eventually came to a halt, it was not properly aligned with the runway.
The instructor, monitoring the frequency, was called to the aircraft. Upon inspection, the instructor found that the left main wheel was locked. While maneuvering the aircraft, the wheel eventually unlocked, but a persistent residual braking effect remained. Because the AFIS and fire services (SSLIA) were closed at the time, and the instructor believed leaving the aircraft on the runway posed a safety risk, the decision was made to restart the engine and taxi the aircraft to the parking area. After taxiing approximately 700 meters, a club member alerted the crew that the left main gear was on fire. The instructor and student evacuated the aircraft, and the fire, which had destroyed the wing, was extinguished by bystanders using a fire extinguisher.
The investigation
The investigation focused on the cause of the residual braking and the subsequent fire. The student pilot noted that the brake handle in the cabin felt completely loose during the second flight, though the brakes had functioned normally during the first flight of the day. The braking system consists of two master cylinders located on the cabin floor, which can be operated symmetrically via the central handle or asymmetrically via the rudder pedals.
A maintenance check of the braking system had been performed ten days prior to the accident, and the flights on the day of the event were the first since that inspection. Post-accident examinations of the wreckage and components in a workshop were unable to identify the specific cause of the residual braking.
Findings
- The fire was caused by the decision to continue taxiing to the parking area while the aircraft was experiencing residual braking.
- The origin of the residual braking could not be determined by the investigation.