Flight control systems involving a Boeing 747-400, N124KK, Adelaide, South Australia, on 22 September 1994

The aircraft made a normal approach and landing on runway 05. As the aircraft was approaching the parking bay tarmac personnel noticed that a section of leading-edge flap was missing from the right wing outboard leading edge. This was later found by the aerodrome safety officer during a runway inspection.

The crew reported that the aircraft had operated normally during the flight.

Investigation revealed that after departure from Melbourne, as the leading-edge flaps retracted, the follow-up mechanism malfunctioned allowing the flap actuator to continue driving the flaps when fully retracted. This caused a flap attachment bracket to fail. When the flaps were selected down the actuator operated normally, with no abnormal indications noticed by the crew. The section of flap associated with the failed bracket separated from the aircraft after landing.

The cause for the follow up mechanism to malfunction could not be determined, and a report from the company has not been forthcoming.