What happened
During cruise flight, the flight crew of a twin-engine transport category airplane detected an odor similar to burning or smoldering electrical equipment. Simultaneously, the crew observed that the landing gear control circuit breaker had popped. Upon consulting the company's Quick Reference Handbook (QRH), the crew found that while the manual addressed hydraulic issues, it did not provide guidance for electrical problems affecting landing gear operation.
The flight crew notified the company's maintenance facility, but the technician on duty was unable to assist. To verify the gear configuration, three fly-bys were performed near the tower. Both tower personnel and the flight attendant reported that the landing gear appeared to be down with the gear doors closed. Despite this visual confirmation, the crew elected to land while the gear handle light indicated an 'in-transit' condition and both main landing gear indicators showed an 'unsafe' status.
During the landing roll, the left main landing gear collapsed. There were no fatalities or injuries reported.
The investigation
Post-accident examination determined that the weight-on-wheels relay, situated in the avionics bay directly beneath the captain's station, had shorted. This short circuit caused the landing gear control circuit breaker to trip. Investigators traced the electrical short to a soda can that had been spilled on the flight deck during a previous flight.
The investigation further revealed that the cockpit floor lacked carpeting or sealing, which allowed fluids and moisture to seep into the electrical compartment located under the floor.