Accident Description
An airline transport certificated pilot was conducting a visual flight rules (VFR) local area sightseeing flight under Title 14, CFR Part 135, in a float-equipped airplane. During cruise flight, a flash fire erupted near the windshield/glare shield area of the cockpit, in front of the pilot. The pilot made an emergency landing, and a passenger assisted by utilizing a fire extinguisher to put out the fire. The airplane received minor damage, and the pilot received second-degree burns to his hands.
Aircraft and Maintenance History
The airplane was manufactured in 1958 and had accrued 3,742 hours on the airframe, and 6.4 hours since the last annual inspection when a 1,000 hp engine was installed.
Postaccident Examination
A postaccident examination of the airplane revealed a pin-size hole in an aluminum fuel pressure bourbon line. This line served as a fixed line between the engine firewall and an airframe longitudinal former, located behind the instrument panel. The bourbon line was situated between flexible fuel pressure lines from the engine to the firewall, and from the airframe former to the backside of the fuel pressure gauge.
An examination of the line at the NTSB Materials Laboratory revealed a circular-shaped hole about 3 inches from the firewall end of the line. A longitudinal cut was made through the hole, which disclosed blue and brown tinting, and evidence of metal flow typical of re-solidification. The features of the hole were consistent with heat damage from electrical arcing. The wall of the tube had no evidence of corrosion.