What happened
During the climb out following takeoff, a domestic air carrier flight encountered a flock of birds. The flight crew reported that the flock was identified too late to perform an avoidance maneuver. As the flock passed on both sides of the aircraft, the crew felt and heard an impact. Following the encounter, the left engine immediately seized, which triggered a fire warning.
The crew successfully extinguished the engine fire and performed an emergency landing at the departure airport. There were no injuries reported following the event.
The investigation
An examination of the engine revealed that the fan module sustained damage during the bird strike. This damage caused the module to rotate approximately 45 degrees, which subsequently pulled the fuel line loose from the fuel/oil cooler. Fire damage was observed in the area of the fuel/oil cooler.
Investigators recovered a double-crested cormorant from the debris path, estimated to weigh 5 pounds intact. Examination of bird debris found within the engine confirmed that at least two birds were ingested during the encounter.