Incident Details
The pilot departed Olympia, Washington, in a Cessna 182R, bound for Renton, Washington. Shortly after departure, the pilot detected a faint odor of electrical insulation but observed no other anomalies. Upon arrival at Renton, the pilot lowered the landing gear. During the landing roll, the main landing gear collapsed.
Post-Crash Examination
A post-crash examination of the aircraft revealed that the hydraulic power pack had worn gears within the pump assembly. This condition would allow the electrically driven pump to operate for longer than normal periods, ultimately resulting in the pump overheating and its associated circuit breaker tripping during the flight. Additionally, the green landing gear "down and locked" annunciator light's manual iris was found to be open only 1/16 of an inch. With the iris stopped down to near total closure, the pilot would have been unable to see the green light had it been illuminated.
Findings
Because the electrically driven pump was out of service due to the tripped circuit breaker, the landing gear would not have had hydraulic pressure to lock into the down position and complete the circuit necessary to illuminate the green light. The pilot failed to verify a down and locked condition other than placing the gear handle in the down position.