What happened
On the evening of June 21, 2003, a Jodel D 140 E registered as F-POPB was preparing for a return flight to Tarbes from an altisurface in Barèges. The aircraft, operated for private use, was being positioned for takeoff on the 21% slope runway. During the maneuver to align the aircraft with the runway axis, the pilot attempted to pivot the plane 20 degrees to the right by applying the right brake.
During this movement, the brake pedal depressed fully, rendering the right brake ineffective. In an attempt to correct the heading, the pilot briefly increased engine power to use the slipstream to assist the turn. However, the loss of braking control caused the aircraft to veer perpendicularly across the runway axis. The pilot attempted to use the left brake to stabilize the direction, but the aircraft continued to move backward down the slope, eventually coming to a stop at the edge of the runway. The aircraft sustained heavy damage.
The investigation
The investigation focused on the mechanical failure of the braking system. Investigators recovered a broken right brake control rod from the wreckage. Analysis of the component revealed a static fracture originating at the base of a thread. The rod was an original part that had been in service for approximately thirty years.
Findings
- The primary cause of the loss of control was the rupture of a brake control rod.
- The failure of the right brake prevented the pilot from executing the necessary turn to align with the runway.
- The application of engine power to compensate for the lack of braking actually induced a leftward yaw, exacerbating the deviation from the runway axis.
- The mechanical failure was due to a fatigue-related static break in the threading of an aged component.