What happened
The pilot was conducting a test flight following maintenance on the tailwheel assembly, which had been performed to address a shimmy issue. During the final approach phase of the landing, control of the aircraft was lost at approximately 20 knots. The loss of control was directly attributed to the tailwheel jamming. Following this event, the aircraft departed the side of the runway, and the left main gear collapsed. This sequence of events resulted in substantial damage to the airframe.
The investigation
The investigation determined that the tailwheel jam was the primary mechanical failure leading to the accident. Further examination revealed that the jam occurred because improper maintenance procedures were followed during the repair. Specifically, the wrong maintenance manual was used when the repairs were made, leading to incorrect installation or adjustment of the tailwheel components.
Findings
The contributing factors to this accident include the improper maintenance of the tailwheel assembly and the use of an incorrect maintenance manual. These errors led to a mechanical failure during a critical phase of flight. The pilot was conducting a test flight to verify the repair, but the underlying maintenance error rendered the aircraft unsafe for operation.