AAIB Reports on Uncommanded Aileron Movements

The UK’s Air Accidents Investigation Board last month issued a final report into two incidents of uncommanded aileron input that occurred on Oct. 7, 2014, aboard a BAe ATP shortly after departure from Bournemouth airport. The two pilots were the sole occupants of the aircraft.

According to the AAIB, the aircraft was being hand flown by the captain and had just leveled off at 7,000 feet when the control wheel turned violently to the left with enough force to pull it out of the captain’s hands. Opposite rudder and heavy aileron forces were required to level the aircraft, although the control wheel was then displaced 45 degrees to the right. The ailerons also became unresponsive for a short period of time before the control wheel was again pulled out of the commander’s hands, but this time to the right. No warning lights illuminated at any time.

The crew returned to Bournemouth after the captain completed a low-speed handling check in which all appeared normal. The crew did notice the cockpit flood lighting flickering on final. On the ground, the crew reported light smoke and an electrical burning smell in the cockpit. A ground engineer reported hearing a bang from the forward fuselage where acrid white smoke later vented. A post-flight investigation failed to identify any faults related to the uncommanded inputs or the smoke. The aircraft has since flown without a reoccurrence of either fault.