EXHAUST SYSTEM

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Description - The exhaust system consists of an exhaust pipe (riser) from each cylinder to the muffler with a single tailpipe which routes exhaust gases out through the lower cowling area. The muffler is located beneath the engine, and is enclosed by a shroud which captures radiated exhaust heat. This heated air is then ducted to the airplane cabin through flexible hoses.
781001 Exhaust System - Inspect for cracks and security. Special check in area of heat exchanger

 Removal of  Exhaust System 
(1) Remove engine cowling.
(2) Loosen left front baffle to allow heat shroud inlet to clear baffle.
(3) Remove EGT probe.
(4) Disconnect flexible heat duct from heat shroud.
(5) Remove clamps securing risers to muffler.
(6) Remove nuts and washers securing risers to engine and remove risers/muffler as an assembly from engine.
(7) Remove screws securing heat shroud to itself, and unwrap heat shroud from around muffler.
(8) Inspect muffler for leaks. Refer to Muffler Inspection below.
Installation of Exhaust System.
(1) Wrap heat shroud around muffler and secure to itself using screws.
(2) Loosely install risers (4 total) to muffler using clamps.
(3) Install riser/muffler assembly to engine using new gaskets.
(4) Tighten risers 200-210 inch-pounds at engine, then tighten clamps connecting risers to muffler.
(5) Reconnect EGT probe.
(6) Reinstall engine cowling.

 Muffler Inspection

(1) Using a flashlight and mirror, examine the interior of the muffler, looking for cracks or general deterioration.
(2) Using visual inspection, examine the exterior of muffler, looking for holes, cracks and burned spots.Pay special attention to areas adjacent to welds and to exhaust gas deposits (which indicate an exhaust leak).
(3) After visual inspection an air leak check should be made on the system as follows:
(a) Attach the pressure side of an industrial vacuum cleaner to the tail pipe opening, using a rubber plug to effect a seal as require
(b) With vacuum cleaner operating, all joints in the exhaust system may be checked by using a soap and water solution and watching for bubbles. Forming of bubbles is considered acceptable; if bubbles are blown away, system is not considered acceptable.
(4) Use a water test to determine muffler integrity:
(a) Seal openings in muffler using rubber expansion plugs.
(b) Using a pressure gauge or manometer, apply approximately 3.0 PSI, +0.5 or -0.5 PSI (6 inches mercury), to interior of muffler and submerge muffler into water. Any leaks will appear as bubbles and can be readily detected.
(c) If any leaks are detected, the muffler must be removed from service and repaired or replaced.
(d) If no defects are found, remove muffler from water, remove plugs and dry muffler with
compressed air.

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