Author Description

The accident occurred when take-off rotation of the aircraft was prevented by an elevator control circuit jam. The take-off was rejected after reaching V1, and wheelbraking and selection of propeller ground finepitch failed to stop the aircraft on the runway. During the overrun the aircraft collided with camera equipment mounted on a building, locally damaging the right wing. A number of potentially serious deficiencies in the flight controls gust lock system were found, although the system passed checks intended to verify its integrity. An undemanded re-locking of the system could not be reproduced during testing, but this could not fully simulate the accident circumstances. It was concluded that the accident was probably caused by a re-engagement of the elevator gust lock induced by the carrying out of a Full and Free controls check at the start of the take-off run. Despite a series of modifications to the flight controls gust lock system by the manufacturer, paritcularly following a major fatal overrun accident which occured at Sumburgh Airport on 31 July 1979, this accident at Liverpool Airport and other possible gust lock related incidents demonstrated that associated unlocking of the flight controls on HS748 aircraft before flight is still not sufficiently reliable.