NTSB Identification: NYC96IA036.
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Incident occurred Wednesday, December 06, 1995 in JAMAICA, NY
Probable Cause Approval Date: 07/31/1998
Aircraft: Boeing 747-240, registration: APBAK
Injuries: 255 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

After takeoff, about 1,000 ft agl, the crew of the Boeing 747-240 heard a 'thudding noise,' followed by a loss of power in the number two engine. An engine shut down was completed, and an uneventful landing was made at the departure airport. The airplane was equipped with General Electric CF6-50E2 engines. Examination revealed that the low pressure turbine module, which included a portion of the fan mid shaft (FMS) and turbine rear frame, was missing. The airplane sustained damage to the left wing leading and tailing edge flaps, the left main wing landing gear doors, and the number one engine. Examination of the number two engine revealed a fracture face on the forward end of the FMS that showed multiple fatigue origins and circumferential cracks. There were also areas on the FMS that were heat affected. The FMS had previously been installed in a CF6-50 engine that had sustained a failure of the number 3 bearing inner race. The engine had been inspected by company personnel, and records did not reflect that they inspected the FMS for heat affected material. Fatigue cracks located in the heat-affected areas were found to have Sermetel paint and debris in the cracks.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

failure of the number two engine fan mid shaft, due a fatigue fracture caused by a previous bearing failure, and failure of the operator's maintenance personnel to detect the cracks during subsequent inspections.

Full narrative available

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