Accident Summary
An aircraft completed a landing with its left main landing gear remaining in the retracted position. The landing gear warning and indicating system had displayed all gear down and locked, so the flight crew did not detect the abnormality until the rollout phase.
Investigation Findings
Examination revealed that the left main gear actuating motor continued to run, which successfully extended the nose gear and right main gear to the down position. However, the left main gear actuating rod fractured under the loads imposed by the motor. This failure activated a micro-switch on the motor, causing the left main gear indicator light to illuminate green, giving a false indication that the left main gear was down and locked. The gear warning horn did not sound because the system interpreted the gear as properly extended.
The jamming of the left main gear in the up position was a direct consequence of the actuating rod failure. The crew had no indication of the problem until after touchdown, when the aircraft began to veer or settle on the runway.