On January 19, 1999, a Boeing 747-100 (registration N481EV) operated by Evergreen Int'l Airlines, Inc. was involved in an aviation accident near Fairbanks, AK. No fatalities were reported. Investigators recorded the probable cause as: The thrust reverser pneumatic drive unit was incorrectly assembled at the previous overhaul. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
After landing, the number four engine thrust reverser remained deployed, causing a tailpipe fire. No cockpit indications were present. Investigation found incorrect assembly of the pneumatic drive unit.
Event Description
After landing, the number four engine thrust reverser remained deployed. A tailpipe fire occurred. No cockpit indications of either the fire or the extended reverser were reported. Ground personnel observed the fire and notified the crew, who subsequently shut down the engine.
Investigation Findings
A teardown inspection revealed that the thrust reverser pneumatic drive unit (PDU) had been incorrectly assembled during its previous overhaul. This overhaul had taken place 113 hours and 26 cycles before the failure. The required stroke of the PDU interlock mechanism is between 1.318 and 1.326 inches. Upon disassembly, the measured stroke was 1.230 inches. This stroke is necessary to allow the gear change mechanism to fully shift from the extend position to the retract position. The fracture surfaces of the PDU retract pawl were indicative of overstress.
Environmental Conditions
The lowest ambient surface temperature the airplane had been exposed to at various airports during the 26 landing cycles was -13 degrees Fahrenheit. The surface temperature at the time of the PDU failure was -27 degrees Fahrenheit.
Probable cause
The thrust reverser pneumatic drive unit was incorrectly assembled at the previous overhaul.
What happened in the 19 Jan 1999 Boeing 747-100 accident near Fairbanks, AK?
After landing, the number four engine thrust reverser remained deployed, causing a tailpipe fire. No cockpit indications were present. Investigation found incorrect assembly of the pneumatic drive unit.
Were there any fatalities in the 19 Jan 1999 Boeing 747-100 accident?
No fatalities were recorded in this accident.
What aircraft was involved and where did it happen?
The accident on 19 Jan 1999 involved a Boeing 747-100, registration N481EV, operated by Evergreen Int'l Airlines, Inc., at Fairbanks, AK.
What was the probable cause of the accident?
The thrust reverser pneumatic drive unit was incorrectly assembled at the previous overhaul.
A SkyWalk Join't 3 paraglider crashed into the ground near Las Vizcachas, Chile, on September 1, 2024. The pilot and passenger sustained serious spinal…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2024-09-01DGAC Chile
A Cessna 172N struck electrical cables while on final approach to land at Aucó Aerodrome in Chile. The pilot was uninjured, but the aircraft sustained damage…
A Bombardier DHC-8-402 suffered a tail strike during landing at Puerto Williams on September 9, 2024. All 76 occupants were unharmed, but the aircraft…
A MYD JS-MD 3 glider veered off the runway and struck a wall at Vitacura Aerodrome on January 6, 2025. The pilot was uninjured, but the aircraft sustained…
A recreational paraglider flight in Puchuncaví, Chile, ended with the pilot sustaining serious injuries after a rapid descent and impact with a hillside on…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2025-03-29DGAC Chile
A Tecnam P2006T landed on its belly at an aerodrome in Poland after the crew failed to confirm landing gear deployment. The incident resulted in no injuries…
