As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TRAINING FLIGHT, LEFT PROPELLER WOULD NOT COME COMPLETELY OUT OF FEATHER. THE ENGINE COULD ONLY DEVELOP 1500 RPM. WHEN THE ENGINE WAS SHUTDOWN ON THE GROUND, THE PROPELLER WENT BACK INTO FEATHER REGARDLESS OF THE PROP CONTROL POSITION. UPON PROP DISASSEMBLY, ONE OF THE FEATHER LATCH WEIGHTS WAS FOUND BROKEN IN HALF. UNDER EXAMINATION THE METAL IN THE BREAK APPEARS VERY GRANULAR IN NATURE AND UNDER MAGNIFICATION THERE IS RUST IN SOME OF THE VOIDS BETWEEN METAL GRAINS.