As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE BREATHER HOSE SWELLED ON INSIDE FROM THE ORIGINAL 1INCH DIAMETER TO .3750 INCH DIAMETER FROM HOT OIL FUMES. THRUSH ADDRESSED THE SAME PROBLEM ON THE MFG POWERED LINE. THIS IS NOT AN ISOLATED INCIDENT. THE CONDITION NOTED CAN ONLY BE FOUND AFTER HOSE REMOVAL. EXTERIOR OF HOSE LOOKS OK. SUGGEST A SCHEDULE OF REPLACEMENT EVERY 2000 HOURS.