As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN)HEATER FAILED PRESSURE DECAY TEST. INVESTIGATION FOUND THE HEAD GASKET TO BE LEAKING. REPLACED THE HEAD GASKET AND APPLIED PERMATEX #1372 AS PER JANITROL OVERHAUL MANUAL. SUBMITTER SUSPECTS THE PERMATEX SEALANT WAS LEFT OUT DURING THE LAST OVERHAUL.