May 21, 2011
Incident
Peach Springs, AZ
InjuriesNone
Phase of Flight-
ConditionsVMC
OperationFAR 135
Probable Cause
A quality control failure in the Sungear, Inc. manufacturing and quality control process allowed sungears with surface finishes of the root fillet radius of the spline that did not conform to the drawing specifications to be released. The surface finish defect caused fatigue cracks to initiate early in the part life.
NTSB ENG11IA032