What happened
A pilot was conducting a visual flight rules sightseeing flight under Part 14 CFR 135 in a float-equipped airplane. During the cruise phase of the flight, a flash fire erupted in the cockpit area near the windshield and glare shield, positioned in front of the pilot. In response to the fire, the pilot performed an emergency landing. A passenger was able to assist by using a fire extinguisher to suppress the flames.
The incident resulted in minor damage to the aircraft and caused the pilot to sustain second-degree burns to his hands. The aircraft involved had been manufactured in 1958, with 3,742 hours on the airframe and 6.4 hours logged since a recent annual inspection involving a 1,000 hp engine installation.
The investigation
Post-accident examination of the aircraft identified a pin-sized hole in an aluminum fuel pressure bourbon line. This line served as a fixed connection between the engine firewall and an airframe longitudinal former located behind the instrument panel. The line was positioned between flexible fuel pressure lines running from the engine to the firewall and from the airframe former to the back of the fuel pressure gauge.
Analysis conducted at the NTSB Materials Laboratory focused on this specific section of the line. Investigators found a circular hole approximately 3 inches from the end connected to the firewall. After making a longitudinal cut through the hole, researchers observed blue and brown tinting along with metal flow patterns characteristic of re-solidification. No evidence of corrosion was found within the wall of the tube.