Incident Description
During cruise flight, the flight crew detected an odor resembling burning or smoldering electrical equipment. The landing gear control circuit breaker had popped. The crew consulted the company's Quick Reference Handbook (QRH), which addressed hydraulic problems but did not discuss electrical problems related to landing gear operation. The company's maintenance facility was informed, but the maintenance person on duty could not assist the flight crew.
Flight Crew Actions
Three tower fly-bys were conducted. The flight attendant and tower personnel reported that the landing gear appeared to be down with the gear doors closed. The flight crew elected to land with the landing gear handle light indicating an 'in-transit' condition and both main landing gear indicators showing an 'unsafe' condition. During the landing roll, the left main landing gear of the twin-engine transport category airplane collapsed.
Examination Findings
Post-incident examination revealed that the weight-on-wheels relay, located in the avionics bay directly under the captain's station, had shorted. This short caused the landing gear control circuit breaker to pop. The electrical short was attributed to the spill of a soda can on the flight deck on a previous flight. The investigation also revealed that the cockpit floor was not carpeted or sealed to prevent fluids or moisture from seeping into the electrical compartment beneath the cockpit floor.
Emergency Extension System Review
A review of the airplane's emergency extension system showed that the landing gear could have been extended if the flight crew had pulled the emergency extension handle.