What happened
On 1 October 2000, a DC-10-30F, registration N601GC, was performing a cargo flight from Stockholm to San Juan with a scheduled refueling stop at Shannon Airport, Ireland. During the takeoff roll from Runway 24, the aircraft was operating at maximum thrust due to deteriorating weather conditions, including windshear warnings and heavy turbulence.
At approximately 300 feet above the ground, the crew experienced a loud bang and a bright flash from the left side of the aircraft, followed by intense vibrations. The No. 1 engine experienced a significant drop in fan speed and a surge in exhaust gas temperature. Shortly after, an engine fire warning illuminated. The crew executed emergency procedures, which included attempting to shut off the fuel supply. However, the engine continued to run at a reduced power setting for several minutes, likely because the high-pressure fuel valve remained partially open.
During the flight, large components from the engine nacelle separated from the aircraft. These parts struck the port inboard aileron and flap, causing structural damage, before falling to the ground. The crew declared an emergency and diverted to London Heathrow. During the approach to Heathrow, the aircraft was routed over densely populated urban areas of London.
The investigation
The AAIB investigation focused on the cause of the engine failure and the subsequent separation of engine parts. Investigators recovered fragments of a fan blade and engine components from the airfield. DNA analysis of organic material found in the engine identified the source as a Grey Heron.
Technical examination of the No. 1 engine revealed that the outer portion of a fan blade had fractured due to the impact of the bird. This triggered a sequence of internal damage, including a burst high-pressure bleed air duct. Crucially, investigators discovered that the aft centre body of the engine had been installed using the incorrect type of bolt. This error resulted in a weakened joint that could not withstand the vibration loads caused by the bird strike, leading to the separation of the centre body and the core exhaust nozzle.
Findings
- The engine failure was caused by the ingestion of a Grey Heron into the No. 1 engine.
- The separation of the engine's aft centre body and core nozzle was due to the use of incorrect attachment bolts.
- The engine fire warning was a secondary effect of the engine surge and subsequent air leaks into the nacelle.
- The aircraft's approach to London Heathrow took it over densely populated areas because the crew was not informed by ATC that the intended route passed over built-up areas.