12.18 Exhaust System

12.18.2 Describe the function of the exhaust manifold.

The exhaust manifold collects the exhaust gases from each cylinder and directs them into a common exhaust pipe.

It is attached to the engine’s cylinder head and provides a passage for burnt gases to exit the cylinders efficiently. By combining the exhaust flow, it ensures the gases are carried away from the engine and expelled safely.

The exhaust manifold is designed to withstand high temperatures and pressures and, in many aircraft engines, also provides a source of heat for systems such as carburettor heat or cabin heating.

Overall, its function is to collect, channel, and discharge exhaust gases, contributing to efficient engine operation and supporting other aircraft systems.

12.18.4 Explain the importance of proper sealing of the exhaust manifold.

Proper sealing of the exhaust manifold is essential to ensure safe and efficient engine operation.

• Prevents exhaust gas leaks:
  Exhaust gases contain carbon monoxide, which is highly toxic. Poor sealing can allow gases to escape into the engine bay or cabin, creating a serious safety hazard.
• Maintains engine efficiency:
  Leaks can disrupt the smooth flow of exhaust gases, reducing engine performance and efficiency.
• Ensures correct operation of auxiliary systems:
  In many aircraft, the exhaust manifold is used as a heat source for carburettor heat and cabin heating. Leaks can reduce the effectiveness of these systems and may allow exhaust gases to contaminate heated air.
• Prevents overheating and damage:
  Escaping hot gases can cause localised overheating, potentially damaging surrounding components, wiring, or structure.