Mufflers

While carrying out Canadian AD CF90-03-R2, large leaks were found in the area surrounding the muffler tail pipe area under the structure for supporting the heat muff shroud. No defects were noticed in a visual inspection of this area. No data tag was on the muffler, so its assumed it is an original unit. The operators logs dont show it ever being changed.

Editorial Staff

Sunday, June 30, 2019 at 12:00 AM ET

Verified

Key Takeaways:

Aircraft exhaust systems are prone to diverse failures such as leaks, cracks, internal separations, and blockages, occurring across various aircraft types and part ages.
Many of these critical defects are difficult to detect through visual inspections alone, often requiring pressure tests or compliance with Airworthiness Directives for discovery.
These exhaust system failures pose significant safety risks, including carbon monoxide exposure and potential engine performance issues.

See a mistake? Contact us.

Cessna 172M Skyhawk

Large Leaks

While carrying out Canadian AD CF90-03-R2, large leaks were found in the area surrounding the muffler tail pipe area under the structure for supporting the heat muff shroud. No defects were noticed in a visual inspection of this area. No data tag was on the muffler, so it’s assumed it is an original unit. The operator’s logs don’t show it ever being changed.

Part total time: Unknown

Cessna 172P Skyhawk

Unserviceable Exit Stack

During a routine 100-hour inspection, the exhaust muffler was suspected unserviceable under a Canadian AD when visually examined. It was removed for a pressure test and failed due to a small hole by the exit stack. The submitter states this area is very hard to inspect visually.

Part total time: 295.0 hours

Cessna 172S Skyhawk SP

Failed Spot Weld

On takeoff, the pilot received a carbon monoxide warning on the primary flight display, then returned and landed without incident. Maintenance verified the presence of carbon monoxide during run-up. Visual inspection revealed a spot weld had failed on the muffler body where the shroud support flange is attached. Muffler replaced with new unit.

Part total time: 174.0 hours

Piper PA-28-180 Cherokee 180

Blocked Muffler

After removing the forward muffler (p/n 66894-00) from the #1 and #2 cylinders, visual inspection revealed the muffler baffling had separated, blocking the exhaust port. A similar condition was found in the aft muffler (p/n 66894-02). Both blockages were missed on an annual inspection conducted 3.0 flight hours earlier.

Part total time: 1359.0 hours

Piper PA-44-180 Seminole

Internal Separation

During an out-of-phase inspection, the right engine’s rear muffler was determined to be separated internally. The outer shroud had become completely detached from the end pipes and the internal pipe. It appears the crack initiated from a repair weld.

Part total time: 61.0 hours

Tecnam P2006T

Deteriorated Ball Joints

On complying with AD 2015-02-09, exhaust pipes were found to be leaking at the ball joints where they connect to the muffler. One side of a ball joint lip on the muffler had deteriorated substantially, from about 0.065 to 0.023 inches. All ball joints showed signs of leaking and heat corrosion.

Part total time: Unknown