Cape Smythe Air Service Flight 310

During the landing roll of the 14 CFR Part 135 scheduled commuter flight, the airline transport certificated pilot noticed a fire in the right engine compartment. He pulled the firewall fuel shutoff for the right engine and stopped the airplane. The passengers were evacuated and the pilot discharged the airplane's fire extinguisher inside the right engine compartment. Additional dry chemical fire extinguishers were supplied by personnel at the airport, and the fire was extinguished. A passenger on the airplane reported that she smelled gasoline and smoke as the airplane was turning onto final, and saw flames as the plane landed. The airplane received structural damage to the right wing. An FAA inspector examined the airplane and reported that the fire pattern was consistent with an in-flight fire on the inboard side of the right engine, that appeared to be concentrated around the hydraulic pump, fuel pump, and the turbocharger. The inspector examined the fuel lines and hydraulic lines to the respective pumps. His examination revealed loose "B" nuts that had no heat discoloration. The airplane's hydraulic fluid reservoir contained fluid. The airplane's right engine hydraulic pump was replaced about 31 hours before the fire. The inspector interviewed the operator's maintenance personnel, and learned that during the hydraulic pump replacement, mechanics removed the right engine's fuel pump to access to the hydraulic pump. Due to the confined area during the reinstallation of the feeder line to the fuel pump, one mechanic held the line in-place, and another turned the fitting with a wrench. A leak check revealed that the fitting was cross-threaded and leaked. The fitting was re-tightened and signed off. The inspector sent the fuel lines and hydraulic lines to the NTSB IIC for examination. Each line was subjected to an air pressure leak test, and no leaks were discovered.

Verbatim NTSB analysis and probable cause from the NTSB dataset