Event Description
During the takeoff roll, after reaching takeoff power, the flight crew heard a loud explosion and aborted the takeoff. While taxiing, air traffic control informed the crew that flames were emanating from the No. 4 engine. The crew stopped the aircraft and executed the engine fire procedures, after which airport fire fighters extinguished the fire.
Investigation Findings
Examination of the failed engine showed that the No. 4 engine had experienced an explosive failure, releasing high-energy engine parts that caused damage to the airframe and the No. 3 engine. Most rotating components forward of the 7th stage compressor disk assembly were released during the failure.
Further examination of the first stage compressor fan blades revealed that the No. 15 first stage fan blade, part number 531601K, had failed due to fatigue. This failure occurred 3.2 hours after the engine had been overhauled.