FAA Sport Pilot Airplane (SPA)Aircraft Performance and SystemsEasy
A four-stroke reciprocating engine, as used in most light sport airplanes, completes one operating cycle through four piston strokes. What is the correct sequence of these strokes?
- ACompression, Intake, Power, Exhaust
- BPower, Compression, Exhaust, Intake
- CIntake, Compression, Power, Exhaust
- DIntake, Power, Compression, Exhaust
Show answer & explanationAnswer & explanation
Correct answer: C. Intake, Compression, Power, Exhaust
The four-stroke cycle occurs in this order: intake (fuel/air mixture drawn in), compression (mixture compressed), power (ignition drives piston down), and exhaust (burned gases expelled).
Why the other options are wrong
- A. Incorrect order — compression must follow intake, not precede it.
- B. Incorrect order — reverses the entire cycle sequence.
- D. Incorrect order — power cannot occur before compression.
Four-Stroke Engine Cycle
The sequence of intake, compression, power, and exhaust strokes that a piston completes to produce mechanical work in a reciprocating engine.
- Intake stroke draws in fuel/air mixture
- Compression stroke compresses the mixture before ignition
- Power stroke is created by spark ignition driving the piston down
- Exhaust stroke expels burned gases from the cylinder
Memory trick: 'In Comes Power, Out' — Intake, Compression, Power, Out(exhaust)