A 1942 built DC-3C was being prepared for a cargo (mail) flight between San Juan-Luis Munoz Marin International Aiport (Puorto Rico) and SaintThomas-Cyril E. King Airport (U.S. Virgin Islands). Onboard a crew of four, 2 pilots and 2 cargo handlers.
The wreckage after the fire was extinguished ©FAA
After the necessary preparations and checklists were completed the Pratt and Withney R-1830-90D radial engines were started and clearance was received to taxi to runway 10, via taxiway "Juliet". While taxing on "Julliet", without any abnormal indication beforehand, the instrument panel and cockpit floor erupted in flames and smoke rapidly filled the cockpit. The aircraft was stopped promptly and the crew initiated the shutdown of the engines. While shutting down the engines the fire became so intense and the smoke so thick that it nearly overwhelmed the pilots. They immediately evacuated the aircraft, together with the cargo handlers. Neither of the four occupants was injured. Before the fire was extinguished the cockpit section of the aircraft was consumed by the fire.
Close up of the burned nose section of the aircraft (©Nikki)
The incident was investigated by the National Transportation Safety Board and they included the following analysis in their final report;
"Examination of the wreckage revealed that the majority of the wires contained inside the main junction box had very little damage except for two wires that had insulation missing. The damage appeared to be associated with the routing of the two wires. Both wires were connected to the battery relay and ran through wires in and around the exposed terminal studs. Heat damage was noted on the insulation of wires and other components that were in contact with the exposed wires. The wires ran from the battery relay to the forward section of the cockpit, where the fire started. Due to the fire damage that consumed the cockpit, the examination was unable to determine what system the wires were associated with. Further examination revealed that the fuel pressure was a direct indicating system. Fuel travelled directly to the instruments in the cockpit via rigid aluminium lines routed on the right lower side of the fuselage, where more severe fire damage was noted. A review of maintenance records did not reveal any evidence of the fuel pressure indicating system lines and hoses having ever been replaced; however, they were only required to be replaced on an as-needed basis. The electrical system, instrument lines, and hoses through the nose compartment were required to be inspected on a Phase D inspection; the airplane's last Phase D inspection was completed about 9 months prior to the accident and the airplane had accrued 313.1 hours of operation since that inspection."
The probable cause was of the accident was determined to be;
"Worn electrical wires and a fuel pressure indicating system hose, which resulted in the fire breaking out during tax"
The NTSB report is available by clicking here.