What happened
On 19 November 2002, a Boeing 727-230F, registration OO-DHY, was performing a scheduled cargo flight from Frankfurt to East Midlands Airport. During the takeoff roll in icing conditions, the crew heard a loud grinding noise, which was immediately followed by the illumination of the engine failure light. The aircraft was traveling at approximately 30 kt when the commander decided to abort the takeoff.
As the crew attempted to reduce power, the commander experienced physical resistance when trying to close the No 1 engine thrust lever. Simultaneously, a fire warning for the No 1 engine activated. The crew followed emergency procedures, including the discharge of both fire extinguishers, though the engine start lever initially remained stuck and could not be moved to the 'CUT OFF' position. Upon reaching a halt, airport fire services arrived and observed flames emanating from the front of the No 1 engine. The fire was eventually extinguished, and the aircraft was towed to a service area.
The investigation
Investigators examined the No 1 engine and discovered significant fire damage on the underside of the engine casing, including soot, oily residue, and damaged wiring. The investigation revealed that fragments from within the engine had penetrated the engine casing, rupturing a fuel pipe and damaging the oil tank.
A borescope examination and engine strip-down confirmed that a second stage low pressure (LP) compressor fan blade had detached from its root attachment. While the attachment pin remained intact, the blade had fractured, and the resulting debris was responsible for the casing breaches and subsequent fuel ignition.
Findings
- The engine fire was caused by the rupture of a fuel pipe following penetration by engine debris.
- The primary cause of the incident was the fracture of a second stage LP compressor fan blade at its root attachment.
- The engine had been inspected in accordance with existing manufacturer instructions, but the failure occurred at 2,369 cycles, which was prior to the next required re-inspection interval.
- Mechanical resistance in the thrust lever and start lever was likely caused by heat damage or debris affecting the mechanical rods connecting the cockpit controls to the fuel control unit.
Safety action
- It is recommended that the FAA and Pratt & Whitney review the inspection and re-inspection intervals for LP compressor second stage fan blades.
- It is recommended that the FAA and Pratt & Whitney mandate the implementation of Service Bulletin 5866, which provides a more durable blade root attachment and a higher life disk.