What happened
On a visual flight rules flight departing from Mascoular, Quebec, a Piper Cherokee PA-28-140, registration C-FXAY, experienced a sudden left roll approximately 25 feet above the ground during climbout. The pilot flying attempted to correct the turn by applying right aileron, but the aircraft continued to bank left. As the second pilot also applied right aileron, the flight controls jammed in the full right position. The aircraft subsequently struck a snowbank along Highway 640, causing the left wing to separate at the fuel tank. The aircraft came to rest in a field, and while the two occupants evacuated the wreckage and were treated for two minor injuries, no fire occurred.
The investigation
Investigators determined that the aircraft's aileron controls were operating in the opposite direction of the cockpit inputs. A preliminary examination of the wing revealed that the bell cranks had been installed backwards. The investigation focused on recent maintenance performed on December 22, 2000, to replace cracked aileron bell crank brackets.
It was established that the aircraft maintenance engineer (AME) performed the task from memory rather than consulting the manufacturer's maintenance manual or microfiche diagrams. Due to the difficulty of removing rusted fasteners and the pressure to complete the work before a holiday break, the AME removed the bell cranks to clean them. Because the parts were not marked with part numbers, the engineer inadvertently interchanged them during reassembly. Furthermore, the required post-installation check to verify proper aileron deflection was not performed. Although regulations require an independent inspection of flight control work, the second AME also failed to detect the reversed controls.
Findings
- The reversed aileron controls were caused by the incorrect installation of the bell cranks.
- The maintenance engineer relied on memory instead of using the maintenance manual or microfiche diagrams.
- The maintenance procedure for verifying aileron deflection following bell crank installation was not followed.
- The independent inspection failed to identify that the control surfaces moved in the wrong direction.
- During pre-flight inspections, the pilots focused on the free movement of the controls rather than verifying that the direction of surface deflection matched the cockpit inputs.