As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TACHOMETER DRIVE ADAPTER IS A 90-DEGREE DRIVE THAT REVERSES OUTPUT ROTATION AND ANGLE OF OUTPUT FROM ENGINE TO DRIVE TACHOMETER SHAFT. FOUND MOUNTING NUT AND FLANGE STILL ON ENGINE ACCESSORY CASE AND ADAPTER HANGING ON TACHOMETER DRIVESHAFT. FLANGE BROKEN OFF OF ADAPTER. SUSPECT CAUSE, DEFECTIVE PART. ADAPTER IS A TELEDYNE CONTINENTAL MOTORS PART.