As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
REMOVED VERNATHERM TO COMPLY WITH MFG SB (CHECK NUT TIGHTNESS). WHEN VALVE REMOVED, THE NUT WAS MISSING. AFTER A THROUGH SEARCH THE NUT WAS FOUND IN THE INBOARD HOSE, OIL COOLER END OF THE COPILOT SIDE OF OIL COOLER (2 OIL COOLER ARE ON THIS INSTALLATION).(K)