What was found
PILOT REPORTED SMOKE IN CABIN. AIRCRAFT RETURNED TO ITS STARTING POINT (ORF). PROBLEM ISOLATED TO GEARBOX BREATHER VALVE STUCK CLOSED. UNIT REPLACED AND OPERATIONAL CHECK GOOD.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
PILOT REPORTED SMOKE IN CABIN. AIRCRAFT RETURNED TO ITS STARTING POINT (ORF). PROBLEM ISOLATED TO GEARBOX BREATHER VALVE STUCK CLOSED. UNIT REPLACED AND OPERATIONAL CHECK GOOD.