What was found
PERFORMED INFLIGHT ENGINE SHUTDOWN BEFORE RELEASE TO SERVICE AS REQUIRED AFTER ENGINE HOT SECTION INSPECTION AND ENGINE INSTALLATION. AT INFLIGHT SHUTDOWN THE ENGINE SPOOLED DOWN AFTER TURNING OFF FUEL AS EXPECTED. HOWEVER, WHEN THE MANUAL FUEL CUTOFF/PROP FEATHER LEVER WAS ACTUATED THE PROP DID NOT FEATHER. INSTEAD IT WINDMILLED AT 40% ENGINE RPM. AFTER LANDING, PROP FEATHERED BLADE ANGLE WAS MEASURED AND FOUND TO BE 62 DEGREES INSTEAD OF 85 DEGREES. THE PROP BLADES WERE STUCK IN THIS POSITION IN FULL ACTUATED FEATHER. PROPS WERE SENT TO TIFFINAIRE WHERE THE PROBLEM WAS VERIFIED AND CORRECTED WITH 2 MT PROP ISSUED SIL'S. 79 AND 81. THIS CONDITION INFLIGHT CAN CAUSE ENGINE DAMAGE DUE TO IT BEING HUNG IN THE CRITICAL RANGE.