What happened
On 24 March 2007, a Beechcraft B200 Super King Air, registration G-BYCP, was operating a commercial passenger flight from Caen, France, to Stapleford Aerodrome, Essex. The flight carried two crew members and five passengers. Shortly after takeoff, the crew attempted to retract the landing gear, but an unusual noise was heard and the red 'gear unsafe' light remained illuminated. While the main landing gear appeared to be in the up and locked position, the nose gear remained partially extended.
After discussing the situation, the crew diverted to Southend Airport, the operator's maintenance base. Despite attempts to recycle the gear and utilize the emergency extension system, the nose gear would not lock down. During the landing at Southend, the nose leg collapsed, causing damage to the nose fuselage structure, the nose landing gear doors, and the propeller blade tips. There were no fatalities and no injuries among the seven people on board.
The investigation
The AAIB investigation focused on the nose landing gear actuator. Examination of the component revealed that the internal threads of the aluminium bronze nut assembly had stripped, preventing the actuator from traversing the steel screw. Investigators found evidence of compacted grease contaminated with aluminium bronze debris and water ingress.
Further analysis showed corrosion pitting on the actuator screw threads and within the internal gears of the housing. The investigation also noted that the actuator was a PMA (Parts Manufacturing Approval) part. While the actuator had undergone a successful end play check only 532 cycles prior to the accident, the presence of water and corrosion had accelerated the degradation of the internal components.