Investigation Summary
The flight was a contract operation for the INS, intended to transport workers whose Bracero program contracts had ended or who were being deported. The aircraft, NC36480, was significantly overdue for its required 100-hour safety inspection; it was already 7 hours overdue when it departed Burbank earlier that morning and nearly 10 hours overdue at the time of the accident. Furthermore, the aircraft was configured with only 26 seats but was carrying 29 passengers (28 Mexican Nationals and one INS guard), resulting in a weight overload of 67 pounds over the maximum allowable limit. During the flight, a latent defect in a gasket within the left engine-driven fuel pump allowed fuel to escape. This fuel ignited, and the resulting fire was fanned by the slipstream to a white-hot intensity. The flames were directed against the left wing's main spar, which eventually lost its structural integrity and failed. Witnesses at a nearby road camp observed the aircraft trailing white smoke before the wing ripped off, causing several passengers to be ejected from the fuselage before the main wreckage impacted the ground and exploded.
Final Conclusions
The Civil Aeronautics Board determined that the probable cause was the in-flight failure of the left wing resulting from fire damage. The source of the fire was a defective left engine-driven fuel pump. The Board noted that the separating gasket in the pump appeared to have been fractured prior to the flight, a latent defect that might not have been detected during a standard 100-hour inspection. However, the Board also highlighted that the operator had flown the aircraft beyond its mandatory inspection period and had overloaded the cabin beyond its certified seating capacity.
Video Analysis
Searching for the Plane Wreck at Los Gatos: A Documentary Performance — Author Tim Z. Hernandez discusses his research into the 1948 crash and his efforts to identify the 28 Mexican passengers who were buried in a mass grave.
If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
Engine-Driven Fuel Pump
A pump mounted on the engine that provides pressurized fuel; a fractured gasket in this unit allowed fuel to leak and ignite.
Main Wing Spar
The primary structural member of the wing; it was burned through by the fuel-fed fire, leading to total structural failure.
Interesting Facts
- 01The aircraft was 9 hours and 44 minutes beyond its required 100-hour inspection at the time of the crash.
- 02The crew mistakenly took a 26-seat aircraft (NC36480) instead of the 32-seat aircraft (NC79055) assigned for the mission.
- 03The plane was carrying 29 passengers (28 migrants and 1 guard), exceeding its certified seating capacity of 26.
- 04Due to the lack of seats, three passengers were seated on unsecured luggage in the aisle without safety belts.
- 05The left engine had 396 hours of service since its last overhaul.
- 06The victims were buried in a mass grave at Holy Cross Cemetery in Fresno, originally marked only as 'Mexican Nationals'.
- 07The crash inspired Woody Guthrie's famous folk song 'Deportee (Plane Wreck at Los Gatos)'.
Safety Actions & Advisories
Inspection Compliance
The investigation highlighted the danger of operating aircraft beyond mandatory 100-hour inspection intervals, though the specific pump defect was noted as latent.