Flight control system event involving an F100, VH-FZO, near Argyle Airport, Western Australia, on 7 March 2014

On 7 March 2014, a Fokker 100 aircraft, registered VH-FZO, departed Perth on a scheduled passenger flight to Argyle, Western Australia. On board was a captain designated as the pilot flying (PF), and a training captain, seated in the right seat, designated as the pilot monitoring (PM).

During the cruise, the aircraft pitched down and both thrust levers came back towards idle to maintain the selected speed during the descent. The rate of descent reached about 1,700 feet per minute and the aircraft descended about 300 ft. The PF then disconnected autopilot 1 and connected autopilot 2.

The aircraft continued to Argyle and the crew commenced descent to the aerodrome. When at about 1,000 ft above ground level (AGL) and about 3 NM from the runway threshold, the PF stated that the thrust levers were stuck. The PM then tried to move the thrust levers and confirmed they were stuck. The PM applied force with both hands on the thrust levers and they jerked forwards, resulting in about a quarter of the normal available thrust. The PM directed the PF to get the aircraft back onto the normal profile and the PF extended full flap. Just prior to touchdown, the PM extended the speed brake and when at about 10 ft AGL, he applied sufficient force to move the thrust levers to the idle position. Engineers found that an elevator servo and a thrust lever servo had failed.

This incident provides an excellent example of how an experienced crew faced with a novel and unanticipated threat, were able to modify their roles and work together to safely complete the flight.

Aviation Short Investigations Bulletin - Issue 33