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What Happens During an Aircraft Exhaust System Inspection?

As an aircraft owner (How Important is Your First Airplane?), you need to ensure that your exhaust system regularly undergoes a detailed inspection and maintenance performed by a licensed mechanic. Remember, the system and its components are prone to cracks and leaks due to the highly corrosive environment in which they operate. 

Visit Knisley Welding Inc. if you need PMA- and FAA-approved exhaust parts for Cessna, Beech, Piper, Partenavia, Helio, Bell, and Mooney. We also offer quality service repair and maintenance to aircraft owners and operators. 

 

What happens if you don’t inspect & maintain your exhaust system?

Failure to immediately address cracks and leaks can compromise the performance and reliability of the engine and may even cause carbon monoxide poisoning to the occupants. While detailed inspection is best performed by the professionals, aircraft owners and pilots should learn to conduct visual examinations and identify telltale signs of exhaust leaks. 

Related article: General Aircraft Maintenance and Safety Tips

Heat and corrosion: The main causes of exhaust failure 

The aircraft exhaust system is exposed to extreme temperatures as it removes gasses from each cylinder head. But once the engine is shut down, the exhaust components rapidly cool down, making them susceptible to metal fatigue and cracks. These extreme and abrupt temperature changes also cause the connections such as the cylinder exhaust flange attachments, slip joints and clamps to leak over time. 

Visual inspections 

Again, aircraft owners and operators can perform visual inspections to help them decide whether immediate repair or proactive maintenance is necessary. 

Damaged muffler. Bulges and wrinkles are a clear indication of overheating and fatigue. 

Exhaust leaks. The telltale signs of exhaust leaks are quite obvious because the gray or black sooty residue accumulates around the leaking area. But sometimes, the leak appears like a yellow stain on the exhaust system itself, although there are cases in which you won’t see any stains. 

Wear and tear on the exposed parts. Aircraft owners and pilots can perform routine or daily inspections of the exhaust system in which they will look for cracks, loose clamps, leaks and scaling on the visible surface. 

General inspection   

When mechanics conduct a general inspection of the exhaust system, they completely remove the shrouds and shields from the muffler and stacks. However, a few cut corners by only partially removing the shroud to have a quick look, a technique that’s generally frowned upon because this is not enough to see all the deformities and cracks in the mufflers. 

Aside from cracks and buckling, mechanics also look for leaks, particularly around the flanges, welds and clamps where leaks generally appear like a yellowish or orangey powder residue. 

Again, not all leaks are visible to the naked eye. For this reason, aircraft mechanics perform a pressure test in which they insert an air source (or regulated shop air) in the tailpipe to pressurize the exhaust to 3-5 psi. Next, they spray a soap-and-water solution on the surface and joints to identify pinholes, cracks or gaps at the slip joints or camps. 

During this process, they’re careful not to over-pressurize the system as doing so causes damage to itself and the engine. 

Related articles: What happens during aircraft maintenance? | Why is it important to aircraft maintenance?

Final word on Aircraft Exhaust System Inspection

Just like the aircraft engine, the exhaust system requires regular maintenance and inspection to prevent cracks and leaks and perform an immediate repair if needed. 

Visit Knisley Welding today if you need services and exhaust parts from an FAA- and PMA-approved company. You can also leave a message here if you have questions about how we can help you with any exhaust-related problems. 

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