What happened
A three-engine jet remained parked outdoors in snowy weather throughout the day. In the two hours preceding departure, the aircraft received three applications of de-ice and anti-ice fluid. During the takeoff roll, sparks were seen emanating from the #2 (center) tail-mounted engine. Although cockpit engine instruments showed no abnormal indications, the flight crew felt a slight vibration and decided to return to the departure airport.
Upon touchdown, the crew selected reverse thrust on all three engines, at which point a fire erupted from the #2 engine. The flight crew and ground crash/fire/rescue personnel responded to the fire; no one was injured.
The investigation
Investigators reviewed an FAA airworthiness directive that required a thorough preflight inspection of the #2 engine inlet and bellmouth area when operating in icing conditions. Maintenance personnel involved in the de-icing and preflight procedures noted that a puddle of de-ice fluid was visible in the #2 engine bellmouth area.
Post-accident examination of the #2 engine identified "soft body" damage, which was consistent with the ingestion of ice, as well as "hard body" damage, consistent with the ingestion of engine parts damaged by ice. Additionally, an examination of the aircraft revealed that a modification to the heated bellmouth drain-line, which had been recorded in the logbook, had not actually been completed.