Uncontained Engine Failure Prompts Evacuation After Landing (N322PX)

Incident Details

The captain reported that during the landing roll, a loud noise emanated from the left engine, followed by heavy smoke and an engine fire warning bell. The aircraft was stopped on a taxiway, and an evacuation was ordered. The flight attendant experienced difficulty opening the floor-level emergency exit. No slide or rope was available for exiting the aircraft. Three passengers received minor injuries when they dropped approximately 5.5 feet to the icy taxiway.

Engine Examination

An examination of the left engine revealed an uncontained failure of the power turbine (PT). A teardown inspection showed that a 'B' nut on the stage 4 compressor bleed tube coupling had become disconnected. This led to a loss of cooling air to the PT rotor cavity, resulting in overheating of the stage 4 turbine disk. Measurements of the stage 3 and stage 4 disks indicated radial (creep) growth of 0.006 inches and 0.150 inches, respectively. There was evidence of heavy blade tip rubs into the stator tip shroud backing material during application of reverse thrust, followed by failure of the stage 4 turbine blades and the PT module.