As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED GRINDING NOISE WHEN STARTER WAS ENGAGED WITH NO MOVEMENT OF PROPELLER. REMOVED STARTER AND DISASSEMBLED. FOUND DRIVE SPLINES ON ARMATURE SHAFT BROKEN OFF. THIS IS SECOND SUCH DEFECT FOUND IN A MONTH. NO APPARENT CAUSE WAS FOUND. NO TOLERANCE COULD BE FOUND IN MM FOR SPLINE WEAR. (K)