Piper PA-30 N7504Y accident near Walla Walla, Washington

Probable cause

A tripped landing gear motor circuit breaker, which prevented the gear from fully locking in the down position, and subsequent collapse during landing. Contributing to the accident was the disabled landing gear warning horn.

NTSB analysis

The pilot reported that he stayed in the airport traffic pattern, and completed one takeoff and landing. Prior to the second landing, the landing gear was down, all indications appeared normal, and he did not hear an audible alert when he reduced power for landing. As the airplane touched down, the landing gear collapsed, which resulted in substantial damage to the wing. The pilot stated that he noticed smoke coming from the circuit breaker panel on the floor as he exited the airplane. The operator reported that they had previously been having trouble with the landing gear circuit breaker popping during gear extension and retraction. Six flight hours prior to the accident, they had replaced numerous landing gear system components including the landing gear motor circuit breaker. Ground and flight tests had been successfully completed without a recurrence, which led them to believe that the situation had been resolved. Post accident examination of the airplane revealed that the landing gear motor circuit breaker had tripped, which prevented the landing gear from fully locking in the down position. The landing gear warning circuit is powered by the landing gear motor circuit, and would not activate with the circuit breaker tripped.

Text from the NTSB. Open the NTSB docket for WPR09LA372 for the full record.