1. On a reciprocating engine aircraft using a shrouded exhaust muffler system as a source for cabin heat, the exhaust system should be A. visually inspected for any indication of cracks or an operational carbon monoxide detection test should be done. B. replaced at each reciprocating engine overhaul by a new or overhauled exhaust system or an hydrostatic test should be accomplished. C. removed and the exhaust muffler checked for cracks by using magnetic particle inspection method or an hydrostatic test should be done on the exhaust muffler.