Amateur-built RV 6 N711KJ accident near Watkins, Colorado

Probable cause

The pilot’s failure to apply adequate torque to a fuel line during recent maintenance, which allowed the line to loosen in flight and fuel to enter the hot engine compartment and resulted in an in-flight fire that consumed the airplane.

NTSB analysis

The pilot reported that he’d been conducting touch-and-go landings in the traffic pattern. During initial climb for the second touch-and-go landing and once the airplane reached between about 200 and 300 ft above ground level, he smelled an unusual odor and noticed flames coming from the floor forward of his rudder pedals. The pilot added that he “immediately rejected the takeoff” and declared an emergency. He then landed the airplane on the departure runway, exited the runway onto a taxiway, and then stopped the airplane. The pilot subsequently turned off the fuel valve, shut down the engine by pulling the mixture to full lean, turned off the fuel valve and electrical power switches, and then exited the airplane. A postcrash fire ensued, which consumed the airplane.

The pilot stated that he had installed all new fuel lines about 1 month or 1.5 flight hours before the accident flight. Postaccident engine examination revealed that all four fuel lines exhibited thermal damage and soot on their exteriors, consistent with exposure to fire. An end of one of the fuel lines had soot deposits in the first three threads of the line’s attachment fitting. If the fuel line had been secured at the time of the fire, no soot deposits would have been inside the threaded fitting. Therefore, it is likely that the fuel line loosened during flight due to the pilot’s failure to apply adequate torque to the line during installation, which allowed fuel to enter the hot engine compartment and led to an in-flight fire that consumed the airplane.

Text from the NTSB. Open the NTSB docket for CEN19LA048 for the full record.