Incident Details
A pilot was transporting a cargo load that included barrels of 100LL octane aviation fuel to a remote airstrip. During the flight, the pilot reported fire and smoke emanating from the cargo compartment. He initiated an immediate descent and landed at the intended destination airstrip.
Post-Landing Observations
After landing, the pilot noticed that fuel was leaking from one of the barrels. Examination revealed that the fire was located between the cargo area flooring and the bottom belly of the airplane. The cargo bay sustained fire and heat damage, and there was melting of the airframe assembly, including the rear spar and several airframe stations.
Electrical Wiring Findings
An area of sooting and a charred section of electrical wiring was discovered below the flooring, adjacent to the mounting position of a lower fuselage beacon that had been removed at some point in the past. The circuit breaker protecting the electrical loads for the airplane's rotating beacons was found in the popped position. When electrical power was applied to the rotating beacon circuit, the upper fuselage beacon functioned properly, and electrical power was present at the charred wiring.