Incident Details
During a climb, a pilot who was also performing maintenance duties as a mechanic heard a pop sound, which was accompanied by a loss of propeller thrust. The pilot attempted to adjust the propeller control, but movement had no effect. An emergency descent was initiated. The pilot reported that a nose-down attitude of 35 to 40 degrees was required to maintain an airspeed of 85 knots during the subsequent forced landing to a road. The engine was not secured prior to landing. The landing was hard, with an estimated descent rate of 1,800 feet per minute.
Examination
Post-incident examination of the propeller system revealed that two staking pins were missing. The guide collar, rod, fork, and piston had rotated around the hub. The propeller blades were disconnected from the pitch change mechanism. The propeller assembly had been overhauled and installed on the aircraft approximately 31.7 hours before the failure occurred.