Accident Summary
After takeoff, while climbing through 500 feet, the airplane abruptly and uncommanded yawed to the left. The pilot attempted to correct with rudder trim, but the trim wheel turned freely. The flight remained in the traffic pattern.
While on short final approach, the controller advised the pilot to go-around because the landing gear was not extended. The pilot lowered the landing gear but landed before the main landing gear locked in place. The pilot reported hearing the gear warning horn while on short final approach with the flaps extended.
Post-Accident Examination
Examination of the airplane revealed that a wire at the micro-switch for the throttle gear warning was broken. When the wire was reconnected, the warning horn operated normally.
The rudder trim actuator and trim wheel were fully displaced to the left. The master link for the rudder trim chain was bent, and the master link lock clip was fractured. Metallurgical examination of the lock clip showed it failed due to overstress failure.
Post-accident retraction and extension tests of the landing gear revealed no evidence of preimpact failure or malfunction.