The pilot advised that when he selected the landing gear down, aerodynamic noises were normal and the main gear green light illuminated. When he closed the throttles the warning horn did not sound, however during the landing roll the left gear collapsed and the aircraft came to rest on the grass adjacent to the landing runway. The left gear uplock had failed to release at the appropriate stage of the extension cycle, possibly due to the incorrect fitment of the uplock release cable attachment bolt. This would have resulted in misalignment of the uplock assembly when the gear was in the up position. When the pilot selected the gear down the actuating rod became bent and prevented the gear from fully extending. However, the visual and aural warning systems for the gear are triggered by a microswitch on the actuator assembly, and if this has moved through its full travel the position of an individual gear leg is not necessarily accurately reflected.
