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A&P mechanic: Powerplant

Ten lessons on the Powerplant rating: how piston engines work and how to inspect them, induction, cooling and exhaust, carburetors and fuel injection, magnetos and starting, oil systems, how turbine engines work, starting and maintaining them, propellers and governors, and engine instruments, fire protection and engine changes.

An unofficial study course for the FAA’s A&P mechanic tests, not made by or affiliated with the FAA.

Part of the Aircraft mechanic (A&P) path.

Take first: A&P mechanic: General.

  1. How a piston engine works

    The four strokes, valve timing and overlap, compression ratio, engine layouts, and the parts inside.

    7 questions

  2. Inspecting piston engines

    The differential compression test and what the leaking air tells you, spark plug readings, oil analysis, borescopes and overhauls.

    6 questions

  3. Induction, cooling and exhaust

    Carburetor ice and carburetor heat, superchargers and turbochargers, baffles and cowl flaps, and exhaust leaks.

    6 questions

  4. Carburetors and fuel injection

    How a float carburetor meters fuel, the mixture control and leaning, fuel injection, and detonation versus preignition.

    6 questions

  5. Ignition and starting

    How a magneto makes a spark, P-leads and hot mags, the impulse coupling, timing, spark plug care, starters and turbine igniters.

    6 questions

  6. Lubrication systems

    What engine oil does, wet and dry sump systems, the valves and coolers, oil grades, and turbine oils and chip detectors.

    6 questions

  7. How a turbine engine works

    The Brayton cycle, the sections from inlet to exhaust, compressors and spools, turbojets, turbofans, turboprops and turboshafts.

    6 questions

  8. Running and maintaining turbines

    The start sequence, hot, hung and wet starts, thrust and temperature readings, borescopes, hot sections, washing and blade damage.

    6 questions

  9. Propellers

    Blade angle and angle of attack, blade twist, fixed pitch and constant speed, how a governor works, feathering, and propeller care.

    6 questions

  10. Engine instruments, fire protection and installation

    Tachometer, manifold pressure, temperatures and thermocouples, firewalls, engine mounts, engine changes and storing an engine.

    6 questions
More info

How it works

Each lesson is a short read with worked examples, then practice questions in our own words, written like the knowledge test’s: most have you pick an answer, some ask you to work out a number (a CG, a rivet length, a torque setting) or name a part, and some have you tap steps into order. You can try again as often as you like; after two misses there’s a button to show the answer. To quiz each other, play Hangar Quiz, which draws its questions from all three courses, alone, on one phone or online.

What do I need to know first?

The General course first. The first lesson recaps the formulas it uses; the rest needs no maths beyond a calculator.

The other aviation maintenance courses

Where is my progress saved? In this browser, like the rest of the site. Nothing to sign up for.

Which rules does it follow? The US ones, as of November 2026: 14 CFR parts 39, 43, 65 and 91, and the FAA’s Airman Certification Standards for aviation mechanics (FAA-S-ACS-1). Other countries license mechanics differently. Check the current rules and the FAA’s test guides before your tests.

An unofficial study course, not made by or affiliated with the FAA; the questions are our own, not from the tests, and finishing it doesn’t count toward a mechanic certificate. For real aircraft, always work from the manufacturer’s current manuals and approved data. Nothing here is a substitute for them or for supervised training.