Jul 9, 2014
Accident
Substantial Garrison, ND
InjuriesNone
Phase of Flight-
ConditionsVMC
OperationFAR 137
Probable Cause
Excessive wear between the power turbine shaft and quill shaft spline, which led to the disconnection of the power turbine wheel, an overspeed of the power turbine, and the subsequent loss of engine power. Contributing to the accident was maintenance personnel’s failure to detect contaminants in the oil filter during the engine’s recent 100-hour inspection.
NTSB CEN14LA358