What happened
On August 4, American Airlines Flight 476 was conducting a scheduled multi-stop service from Tulsa, Oklahoma, to La Guardia Field, New York. The flight included stops in Joplin and Springfield, Missouri. After departing Springfield at 11:53, the Douglas DC-3 climbed to a cruising altitude of 7,000 feet. Shortly after takeoff, the crew began transmitting distress calls via company frequency, reporting that the number two engine was on fire. Other aircraft in the vicinity and ground stations in St. Louis also intercepted these emergency transmissions.
Witnesses on the ground observed smoke and flames trailing from the right engine along the flight path. Military radar tracked the aircraft until it disappeared near Fort Leonard Wood. An Army pilot flying nearby reported seeing the aircraft on final approach to runway 14 at Forney Field, but shortly thereafter, a message arrived stating the plane had crashed short of the runway. The accident resulted in all 25 occupants (the crew and 23 passengers) being killed. Due to the dense woods at the crash site, emergency responders could only reach the wreckage after Army engineers cleared a path with bulldozers.
Findings
Investigations into the accident determined that the primary cause was the installation of an unairworthy cylinder in the right engine. This specific component failed near its base after fewer than six hours of use, triggering an intense fire. Several contributing factors were identified:
- The failure of the No. 12 cylinder led to a fire that became uncontrollable.
- The right main tank fuel shutoff valve remained open, which intensified the blaze.
- Fire damage was so severe that the crew was unable to close the fuel valve.
- Existing visual inspection protocols used by the airline failed to detect the defective part.
- Maintenance procedures for handling cylinders had been altered by verbal instructions from the carrier's engineering department, deviating from the manufacturer's recommended overhaul manual.