As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER REMOVING THE LT OIL COOLER SUPPLY HOSE AT THE CASE FOR ACCESS TO MAGNETO, IT WAS NOTICED THAT THE NUT OFF THE END OF THE VERNATHERM WAS STUCK IN THE FITTING STICKING OUT OF THE CASE. VERNATHERM WAS REMOVED AND REMAINING PARTS LOCATED. INSPECTED SEAT AREA AND FOUND NO UNUSUAL MARKS. REMOVED AND INSPECTED SUCTION SCREEN AND OIL FILTER ELEMENT. NO UNUSUAL CONTAMINANTS NOTED. THIS HOSE CONNECTION HAD BEEN REMOVED 13 HOURS PREVIOUS FOR OTHER MX AND NO NUT WAS VISIBLE AT THAT TIME. SB 518B APPLIES BY PN, BUT THIS VALVE IS A HIGHER SN THAN THAT SPECIFIED IN THE SB. THIS ENG IS A FACTORY REBUILT 8/27/1994.