NYC96IA036

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.

On December 6, 1995, about 2150 eastern standard time, a Boeing 747-240, APBAK, operated by the Pakistan Government as Flight 722, sustained minor damage during an uncontained engine failure after takeoff from the John F. Kennedy International Airport (JFK), Jamaica, New York. Visual meteorological conditions prevailed for the commercial passenger flight that departed, at 2148. The crew of 15, and 240 passengers, were not injured. An instrument flight rules flight plan had been filed for the flight conducted under 14 CFR Part 129.

The three flight crewmembers provided similar accounts of the event. In the Flight Engineer's statement, he said that the engine start and taxi were normal, and full power was applied before the airplane reached 80 knots. At that time all of the engine parameters were equal. During the climb, about 1,000 feet, a "thudding noise" was heard on the left side of the airplane. This was followed by all of the parameters of the number two engine falling to zero, which included the oil quantity. There was no engine fire warning light. An engine shut down was completed, and the airplane was vectored by the Air Traffic Controller while they "dumped" fuel. The airplane was then flown back to JFK, and completed an uneventful landing on runway 31L, at 2311. The airplane was taxied to the gate and the passengers deplaned. An emergency evacuation was not performed.

Two NTSB Powerplant Group Chairman were assigned to the accident at different times. The first Powerplant investigator conducted the on scene investigation. A second Powerplant investigator conducted the examination of the engine at the General Electric facility, Ontario, California.

The airplane had been equipped with General Electric CF6-50E2 engines. Examination of the airplane revealed that the low pressure turbine (LPT) module, which included a portion of the fan mid shaft (FMS), exhaust cone, exhaust nozzle, and turbine rear frame were missing. The LPT case had separated from the turbine mid frame. The airplane sustained damage to the wing adjacent to the number two engine, the left wing leading and tailing edge flaps, and to the left main wing landing gear door. Additional damage was observed to the number one engine nacelle, fan, and engine core.

The NTSB Powerplant Group Chairman's Factual report dated June 5, 1997, stated that the engine examination was conducted on January 3, 1996. The disassembly of the engine revealed that the FMS had multiple fractures between 21 and 26 inches aft of the forward end. The report also stated:

"...The visual and scanning electron microscope (SEM) examination of the fracture face on the forward end of the FMS showed there were multiple fatigue origins and circumferential cracks on the outer diameter (OD) of the shaft. The air duct forward and center stiffener rings were also found to have fatigue cracks that were parallel to the centerline of the air duct...GEAE's examination of the FMS showed that there were areas on the FMS OD that were heat affected, but the Sermetel paint over those area was not rubbed. Fatigue cracks that were located in the heat-affected areas were found to have Sermetel paint and debris in the cracks. GEAE provided the Safety Board with a summary of the maintenance history of the FMS that fractured. The FMS had previously been installed in a PIA CF6-50 engine that had sustained a No. 3 bearing inner race failure. The records did not show that PIA had inspected the FMS for heat affected material that would have occurred if the FMS had been rubbed following the bearing failure or at any of the subsequent maintenance exposures."