Boeing 747 N704CK incident near Newark, New Jersey

Probable cause

An engine fire in the No. 3 engine due to the failure of, and subsequent flammable fluid leak from, one of three fuel or hydraulic lines located in the engine's accessory raceway that ignited when the fluid came in contact with the hot engine cases. Contributing to the incident were the lack of adequate inspection and test requirements and appropriate life limit or inspection interval requirements by the manufacturer.

NTSB analysis

The cargo airplane experienced an in-flight engine fire in the No. 3 engine during climb. The flight crew declared an emergency, shut down the engine, discharged two engine fire suppression bottles to extinguish the fire, and dumped fuel in preparation for landing. The aircraft landed without incident and there were no reported injuries. Examination of the airplane and engine revealed that heat distress and fire damage localized in an area of the engine's accessory raceway where various oil, fuel, and hydraulic lines and hoses were located. The lines and hoses were pressure tested to isolate the source(s) of the flammable fluid leak and three tubes were found to leak. Those three tubes were sent to the manufacturer for further evaluation; however, due to the extensive fire damage, it could not be determined which of the three tubes was the original source of the flammable fluid leak. There were no life limit or required pressure tests in place for any of the three tubes.

Text from the NTSB. Open the NTSB docket for ENG08IA022 for the full record.