What was found
PILOT REPORTED BAD LT MAG DROP. LT MAG REMOVED AND VISUAL INSPECTION REVEALED MISSING TOOTH ON IDLER GEAR. ALL REMAINING TEETH FOUND TO BE DISTORTED. IDLER GEAR BOSS ON CRANKCASE FOUND LOOSE. LT BOLT SAFETY BROKEN. RT HAD STUD WITH COTTER PIN THROUGH NUT, HOWEVER, SHOULD HAVE BEEN BOLT WITH SAFETY WIRE. THE STUD APPEARS TO HAVE BACKED OUT NUT, COTTER PIN AND ALL. PILOT OF A/C WENT TO OFF ON MAG SWITCH AND BACK ON AND NOTICED BACKFIRE. THIS AND IMPROPER INSTALLATION OF GEAR ARE SUSPECT TO THE FAILURE.