Canadian investigators have disclosed that a SkyWest Airlines Bombardier CRJ200 which emitted flame from an engine on start-up had accumulated de-icing fluid in the powerplant.
The jet (N430SW) had been preparing to depart Winnipeg for Minneapolis and had taxied to the de-icing area, where fluid was applied with the left-hand General Electric CF34 engine shut down.
As it proceeded to the runway, on taxiway H, the jet's crew attempted to start the engine.
But the pilots received a "hot-start" indication with temperatures of 600C, says the Transportation Safety Board of Canada, and carried out a shutdown procedure.
"[Winnipeg] tower advised the crew that flames had been observed coming from the engine and that [the firefighting service] was being dispatched," it adds.
The aircraft underwent a maintenance inspection after returning to the gate. While there was no indication of damage, says the board, maintenance personnel found a "significant" quantity of de-icing fluid in the affected engine.
Investigators state that the aircraft involved in the 26 January incident was released to Minneapolis once the borescope inspection was complete and dry motoring was performed.