What happened
On March 9, 2005, a Murphy Rebel amateur-built aircraft, registered F-WNOA, was conducting a test flight at Tarbes Lourdes Pyrénées Airport. The aircraft was being operated by a private owner who had recently performed maintenance to reinforce the flap controls and the attachment of the right main landing gear wheel fairing.
During taxiing toward runway 02, the crew focused their attention on verifying the landing gear's functionality. At the holding point, air traffic control requested a rapid departure to accommodate an approaching commercial airliner. In an effort to comply, the pilot completed the pre-takeoff checks quickly and lined up on the runway. As the aircraft began its takeoff roll, the pilot applied left stick input to counteract the wind effects; however, the aircraft instead rolled to the right. In an attempt to correct the unexpected movement, the pilot applied further left input, causing the aircraft to veer sharply off the runway. The right wing struck a beacon, causing the aircraft to pivot around the obstacle before coming to a halt. The incident resulted in damage to the right wing, the propeller, and the right main landing gear.
The investigation
The investigation focused on the recent maintenance performed on the aircraft's control surfaces. It was established that during previous test flights, the builder had noted excessive flexibility in the flap controls. To rectify this, the builder removed the flap control rod, the bellcrank, and the aileron (flaperon) control linkages.
During the reinstallation of these components, the builder inadvertently swapped the positions of the two identical control linkages on the bellcrank. Because the two linkages are visually identical, the error was not immediately apparent. Furthermore, the investigation found that while the crew had checked the flap operation during pre-flight inspections and at the holding point, they failed to verify the direction of aileron deflection.