As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PN 4508-042 WAS OF A LOWER THAN SPECIFIED HARDNESS WHEN INSPECTED. THIS LOWER HARDNESS ALLOWED THE PART TO WEAR AT A FASTER RATE THAN EXPECTED. THIS WEAR ALLOWED THE DRIVE SPRING TO DISENGAGE FROM THE DRIVER IN THE PROPELLER GOVERNOR AND PERMITTED THE PROPELLER TO OPERATE AT A SPEED FASTER THAN SPECIFIED. THE PART HAS BEEN IN SERVICE SINCE 1977.