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PPL » Aircraft Tech Knowledge (A) » Engines – General Piston Engines

12.10 Engines – General Piston Engines

12.10.2 Identify typical cylinder configurations used for aircraft piston engines.

Typical Piston Engine Configurations


12.10.4 Explain the function of the main components of a four-stroke cycle piston engine including:

(a) cylinders;

It's a chamber where fuel is combusted and power is generated.

The cylinder consists of a piston and two valves at the top; an inlet and exhaust valves.

The piston moves up and down, and its reciprocating motion generates power that turns the propeller.

  • Made of steel, smooth inner surface
  • Air-cooled, have closely spaced external cooling fins

(b) cylinder heads;

Provides the mounting structure for various components such as the inlet and outlet exhaust valves and ducts, spark plugs, injectors, and (in some head designs), the camshaft.

Contains the passages for coolant, oil, and combustion gases.

(c) pistons;

  • Cast from aluminum alloy.
  • Close fit with cylinders.

(d) connecting rods;

  • The Pistons are attached to crankshaft by connecting rods. Piston is linked to rod by gudgeon [or wrist] pin.
  • The ‘big end bearing’ links the con rod and crankshaft.
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