Cessna 172RG N5145U accident near Tulsa, Oklahoma

Probable cause

A shorted terminal lug on the landing gear hydraulic pump which resulted in a cabin fire. Contributing to the accident was the lack of clear installation procedures for the hydraulic pump.

NTSB analysis

According to the certified flight instructor (CFI), the landing gear was lowered once during the instructional flight while practicing a slow flight maneuver. When the pilots returned to the airport and lowered the landing gear in preparation for landing, flames erupted from under the instrument panel and the carpet on the floor caught fire. The pilots declared an emergency before the radio failed. They pulled the mixture control to the idle cutoff position, but the fuel selector could not be turned off due to the flames. The cabin filled with smoke, the instruments were unreadable, and the pilots had difficulty breathing. The CFI opened his (left) door, causing the airplane to yaw to the left, and he used right rudder to compensate, while the rudder pedals were engulfed in flames. In the ensuing forced landing, the instructor was able to avoid power lines but was unable to clear a fence. The airplane struck the fence and came to a stop suddenly. Examination of the airplane revealed that the terminal lug on the hydraulic pump was improperly covered and had shorted. Additionally, the installation procedures for the hydraulic pump did not provide clear guidance on the proper method to cap the terminal lug.

Text from the NTSB. Open the NTSB docket for CEN10LA572 for the full record.