What happened
The incident occurred during ground operations immediately following maintenance work on the aircraft's engine. The carburetor had been previously removed and reworked before being reinstalled. This installation process included a standard leak check to ensure integrity. Following the mechanical work, the pilot occupied the left front seat while a passenger who was also a mechanic took the right front seat.
The pilot primed the engine and initiated the start sequence. The engine ran for approximately 20 seconds before stopping unexpectedly. The occupants discussed the issue and determined that the fuel line was likely air-bound. To keep the engine running, they decided to use the primer during restart attempts. After restarting, the engine continued to operate via the primer for an additional 30 to 40 seconds.
At this point, the pilot observed a fire in the lower right corner of the cockpit. The occupants attempted to evacuate the burning aircraft. During the evacuation, the pilot fell, and the passenger returned to assist. Shortly thereafter, the right wing fuel tank exploded. Both occupants sustained burns from the incident. The pilot succumbed to injuries two days later.
The investigation
A post-accident examination of the aircraft revealed critical mechanical failures. Investigators found that the main fuel line connecting the gascolator to the carburetor had broken. This breakage allowed fuel to leak into the cockpit area, where it likely ignited, leading to the fire and subsequent explosion of the right wing tank.
Findings
The sequence of events indicates a catastrophic failure of the fuel system following maintenance. The pilot and the passenger/mechanic were both injured by the fire and explosion. The root cause was traced directly to the broken fuel line, which compromised the integrity of the fuel delivery system after the carburetor reinstallation.