48-25-02: Welded Exhaust Muffler

48-25-02 CESSNA: Applies to All 120 and 140 Aircraft Equipped With Cessna Welded Exhaust Muffler Assemblies. Inspection required each 25 hours of operation. Remove the carburetor air heater muff and cabin heater muff and inspect the muffler assemblies for any evidence of cracks paying particular attention to the areas of the mufflers and stacks adjacent to where the exhaust stacks and tailpipe are welded to the muffler assembly. The present placard calling for inspection of the mufflers every 100 hours should be revised to call for this inspection every 25 hours. This directive is intended to apply to only those aircraft equipped with exhaust muffler assemblies that are fabricated by welding exhaust stacks to muffler.