What happened
The flight proceeded normally from takeoff through a climb to a cruise altitude of 33,000 feet. After leveling off, the relief pilot departed the cockpit for a rest period. Shortly thereafter, the captain observed several indications of an emergency: the number 2 engine master warning light illuminated, a level 3 alert appeared on the Engine and Alert Display, and a red light appeared on the number 2 fire handle and fuel shutoff lever. Although the fire bell did not activate, the crew performed memory items and initial action checklists for an engine fire, subsequently shutting down the No. 2 engine.
The captain discharged one engine fire bottle, but the fire light remained illuminated; a second bottle was then discharged with no change in the indication. The captain requested the relief pilot return to the cockpit and notified Air Traffic Control that the number 2 engine was on fire. The crew requested an immediate descent into Charlotte, which was approximately 35 miles away. During the descent, the aircraft encountered moderate turbulence, light hail, and heavy rain. The crew also observed a bright flash to the left of the nose, potentially a lightning strike.
The first officer initiated fuel dumping, which was not terminated prior to landing. The crew prepared for an emergency evacuation and reviewed procedures for the potential loss of a second engine. The aircraft landed on the runway without further incident, and the engine fire indication remained active after the plane came to a stop. The crew completed the evacuation checklist and ordered an evacuation of the MD-11.
The investigation
Maintenance personnel from Delta Air Lines examined the No. 2 engine and found that one fire loop had chafed through an adjacent integrated drive generator (IDG) feeder cable inside the engine cowling. This chafing created a direct 115 volt AC connection between the IDG and the fire detection control unit, resulting in an electrical short and the complete failure of the detection control unit. This failure produced the false fire warning in the cockpit. There was no evidence of an actual fire in the No. 2 engine.
Records show that Boeing had issued Service Bulletin MD11-71-086 to address IDG wire harness support brackets, later elevating it to an Alert level. While Delta Air Lines had issued an Engineering Order to modify all engines by November 2002, the specific engine involved in this event had been replaced on March 28, 2002, with an engine that had not yet been modified according to the order.