59-11-03 MOONEY: Applies to Mark 20A Aircraft Through Serial Number 1534.
Compliance required as indicated.
To guard against the possibility of carbon monoxide entering the cabin, the following inspection and/or repair is required:
(1) Before next flight, visually inspect the exhaust pipes for cracking around the heater jacket bulkheads. Repair or replace as required. No welding is permitted inside the muff or at heater jacket bulkheads.
(2) Within next 25 hours of flight and periodically every 50 hours thereafter, remove the heater muff jacket and inspect the complete exhaust system for cracking. Repair or redlace defective parts as required. The 50-hour inspection is not required if exhaust heater muff assembly P/N 6363 is installed.
(Mooney Service Letter 20-38 concerns this subject.)