Piston Engine Fundamentals
Configuration and induction
Know the four-stroke cycle: induction, compression, power and exhaust. Understand horizontally opposed and radial layouts, and the difference between normally aspirated and turbocharged induction. Traps include the question of valve overlap and why a turbocharger uses a wastegate to limit boost.
Ignition and fuel delivery
Ignition uses magnetos and spark plugs, with two independent circuits for redundancy. Carburettors use a venturi and float chamber; fuel injection meters fuel directly. Know carburettor icing: it can occur at outside air temperatures well above freezing, especially at low power with high humidity. Traps include the difference between carburettor heat and cabin heat, and the effect of mixture leaning at altitude.
Lubrication and cooling
Lubrication uses a dry-sump or wet-sump system, with a pump, filter and cooler. Cooling is usually air-cooled with cylinder fins and baffles. Traps include the difference between oil pressure and oil temperature indications, and the fact that a sudden oil pressure loss requires immediate action.
Worked example
If carburettor ice is suspected, apply carburettor heat and expect a temporary rough running as ice melts. Rule of thumb: carburettor ice is most likely at low power with high humidity, and carburettor heat is the first response.