As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETAINER NUT WAS NOT CRIMPED PROPERLY AT MANUFACTURE CAUSING NUT TO BECOME LOOSE AND WEAR RAPIDLY. THIS PART WAS VERY CLOSE TO FAILING AND LYC SB 518B SHOULD BECOME AN AD SO THAT THESE DEFECTIVE VALVES MUST BE LOOKED AT BEFORE SOMEBODY GETS HURT.