Powerplant Oral Exam Questions and How to Answer Them
Powerplant oral questions come from the 13 Powerplant subjects of the FAA's Aviation Mechanic ACS, from reciprocating and turbine engines to propellers. Every applicant gets at least 4 random powerplant questions, plus one more for each Powerplant ACS code missed on the knowledge test, up to 34. Below are 12 sample questions with short answers, the FAA handbook chapter for each, and a simple way to answer out loud.
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What the powerplant oral covers
The powerplant oral covers Section III of FAA-S-ACS-1, which has 13 subjects lettered A through M. Each oral question carries an ACS code such as AM.III.H.K3, where III is Powerplant and H is the subject.
| Code | Powerplant subject |
|---|---|
| AM.III.A | Reciprocating Engines |
| AM.III.B | Turbine Engines |
| AM.III.C | Engine Inspection |
| AM.III.D | Engine Instrument Systems |
| AM.III.E | Engine Fire Protection Systems |
| AM.III.F | Engine Electrical Systems |
| AM.III.G | Engine Lubrication Systems |
| AM.III.H | Ignition and Starting Systems |
| AM.III.I | Engine Fuel and Fuel Metering Systems |
| AM.III.J | Reciprocating Engine Induction and Cooling Systems |
| AM.III.K | Turbine Engine Air Systems |
| AM.III.L | Engine Exhaust and Reverser Systems |
| AM.III.M | Propellers |
The ACS says an applicant is not permitted to know ahead of time which selections from each subject will be on the test. Prepare for all 13.
How many powerplant oral questions will you get?
You will get between 4 and 34 powerplant oral questions. The number depends on your Powerplant knowledge test report (AKTR), according to the FAA's Mechanic Test Generator (MTG) FAQ:
- Minimum 4. Even with 100 percent on the written, the MTG adds 4 random powerplant questions.
- One per missed ACS code. Each different code on your AKTR adds one question. Several misses under the same code add only one.
- Maximum 34. An applicant who passed the written with 70 percent could get the full 34.
Every question on the DME's test planning sheet must be asked, and the DME does not pick and choose. You answer out loud with no reference material, and the 70 percent passing standard applies to the powerplant oral as a whole, not subject by subject. To read the codes on your own report, see A&P ACS codes: know your codes before the oral. For the full picture of test day, see the A&P oral and practical exam guide.
Sample powerplant oral questions by subject
These 12 practice powerplant oral questions cover 12 of the 13 subjects. They come from DMEReady's question pool, which is written from FAA handbooks and tagged with ACS codes. They are not copied from the FAA's test generator. The FAA's own published sample test shows the style:
AM.III.E.K4: Where are fire switches normally installed?
AM.III.L.K1: What are two general types of exhaust systems in use on reciprocating aircraft engines?
From the FAA sample oral and practical test, Section III (Powerplant).
Reciprocating Engines (AM.III.A.K8)
What does a cylinder compression test tell you about the cylinders?
Whether the valves, rings, and pistons seal the combustion chamber; with too much leakage the cylinder cannot make full power. It tells you whether a cylinder needs replacing, and low compression can mostly be traced to leaky valves. Make sure the ignition switch is off before you start. FAA-H-8083-32B, ch. 10
More reciprocating engine practice questions
Turbine Engines (AM.III.B.K5)
Why is maintenance of the compressor, or cold section, of a turbine engine such a concern?
Blade damage can cause engine failure. Dirt buildup on the blades cuts efficiency and can cause poor acceleration and high exhaust gas temperature, and loose objects like pencils, tools, and flashlights can be drawn in and damage the fan, so carry nothing in your pockets around a running turbine. FAA-H-8083-32B, ch. 10
More turbine engine practice questions
Engine Inspection (AM.III.C.K3)
After a sudden reduction in rpm, how do you act on metal particles found in the oil?
Check the oil screens or filters, and strain the drained oil through a clean cloth. Heavy metal particles mean a definite engine failure and the engine must be removed; fine filings mean you continue the inspection, and if there are no heavy particles you check the oil again after running the engine. FAA-H-8083-32B, ch. 8
More engine inspection practice questions
Engine Instrument Systems (AM.III.D.K11)
What do the markings on an engine instrument face tell you?
A red line is the point beyond which operation is dangerous, a red arc is a range you may pass through but not operate in, yellow is caution, and green is the normal range. A white slippage mark shows whether the cover glass has moved, which would put the other markings in the wrong place. FAA-H-8083-32B, ch. 10
More engine instrument systems practice questions
Engine Fire Protection Systems (AM.III.E.K2)
A Fenwal system is wired to employ a loop circuit, and a break develops in the loop. What does the system do?
It still signals fire or overheat; one open circuit does not stop it. If there are several breaks, only the section between the breaks stops working. FAA-H-8083-31B, ch. 17
More engine fire protection practice questions
Engine Lubrication Systems (AM.III.G.K6)
You find metal particles or flakes in the oil filter element or screens. What does that tell you?
Premature or excessive engine wear. Abnormal metal means more work to find the source and decide on corrective maintenance; a spin-on filter must be cut open to inspect. FAA-H-8083-32B, ch. 6
More engine lubrication practice questions
Ignition and Starting Systems (AM.III.H.K3)
Why does a magneto need an impulse coupling for engine starting?
At cranking speed the magneto turns too slowly to make a spark that will jump the plug gap. The coupling winds a spring, then releases it near top dead center to spin the magnet quickly for a strong spark, and it retards the timing during the start to prevent kickback. FAA-H-8083-32B, ch. 4
More ignition and starting practice questions
Engine Fuel and Fuel Metering Systems (AM.III.I.K2)
In a float carburetor, how is the fuel level in the float chamber held nearly constant?
By a float-operated needle valve and seat: the rising float closes the valve, and while the engine runs the valve sits partly open to match demand. The level stays slightly below the discharge nozzle so it meters correctly and does not leak when stopped. FAA-H-8083-32B, ch. 2
More engine fuel and fuel metering practice questions
Reciprocating Engine Induction and Cooling Systems (AM.III.J.K8)
How do opening or closing the cowl flaps change the engine temperature?
Closing them shrinks the exit area, so less air flows over the cylinder fins and the temperature tends to rise. Opening them increases cooling airflow and the temperature tends to drop. FAA-H-8083-32B, ch. 6
More induction and cooling systems practice questions
Turbine Engine Air Systems (AM.III.K.K8)
Why must icing protection be provided on a turbofan engine inlet?
The fan is the first thing the incoming air meets, and ice that forms on the inlet lip can break loose and damage it. Warm air bled from the compressor is ducted through the inlet, and through the inlet guide vanes if the engine has them. FAA-H-8083-32B, ch. 1 and 3
More turbine engine air systems practice questions
Engine Exhaust and Reverser Systems (AM.III.L.K1)
How would you spot an exhaust leak on a reciprocating engine exhaust system?
Look for a flat gray or sooty black streak on the pipes near the leak; black soot around a gasket means the gasket has failed. Check every clamped and exhaust port connection, since leaks usually come from poor alignment of two mating parts. FAA-H-8083-32B, ch. 3
More engine exhaust and reverser practice questions
Propellers (AM.III.M.K6)
What makes an aluminum propeller blade a reject?
A transverse crack or flaw of any size, or multiple deep nicks and gouges on the leading edge and face. No repairs are allowed to the shanks of aluminum-alloy adjustable-pitch blades, and suspected cracks are confirmed with dye penetrant. FAA-H-8083-32B, ch. 7
More propeller practice questions
How to answer powerplant oral questions out loud
A strong spoken answer has three parts: say the answer, explain why, then name the safety or inspection point. Take the metal-in-the-oil question:
- State the answer. "Heavy metal particles mean a definite engine failure. The engine comes off."
- Explain why. "Metal in the screens is a sign the bearings are failing."
- Add the inspection angle. "If it is only fine filings, I keep inspecting to decide if it is serviceable, and I check the oil again after a run."
Habits that help on the powerplant oral:
- Say which engine type you mean. Many topics differ between piston and turbine engines. If the question is not clear, say which one you are answering for.
- Keep it short and complete. The ACS tells examiners that extra detail in parentheses in the answer key is not expected to be recited. Cover the key point and stop.
- Do not invent numbers. If you do not remember a limit, say it comes from the manufacturer's data and explain what you would check. A guessed figure can undo a good answer.
See also what a DME asks and how to pass the A&P oral. The other sections have their own guides: General oral questions and Airframe oral questions.
Practice your powerplant answers out loud
DMEReady is an AI voice examiner: you answer out loud in your browser and it asks follow-up questions like a DME would. After each session you get a report of what you covered, what you missed, and where to read in the FAA handbooks. Your first drill is free, with no sign-up.
Start a free powerplant drillFrequently asked questions
How many questions are on the A&P powerplant oral?
At least 4 and at most 34. You get 4 random powerplant questions, plus one for each different Powerplant ACS code you missed on the knowledge test.
Can I bring my notes or the powerplant handbook to the oral?
No. You may not use any reference material to answer oral questions. References are allowed for the questions asked during the practical projects.
Can the DME skip questions or add their own?
All questions on the test planning sheet must be asked, and the DME does not get to pick and choose which ones.
Do I have to pass every powerplant subject?
No. The 70 percent standard is applied to the whole oral test, not subject by subject, so a weak subject does not fail you by itself.
I am testing at my school before my written tests. How many powerplant oral questions will I get?
If you are authorized to test under 14 CFR 65.80 before the written tests, the test generator works as if you scored 70 percent. Expect the maximum of 34 powerplant oral questions.
Oral coming up soon? Try the full thing free for 30 days
We are running a small pilot before launch. If your oral and practical is in the next few weeks, you get every section of the voice mock oral free for 30 days, no card. In return, tell us honestly what helped and what didn’t.
Start the free pilotLimited spots. The pilot closes on November 30.
Passed a written? Get your oral study plan by email
Paste the ACS codes on your Airman Knowledge Test Report (AKTR). We’ll email you a study plan now, then two short tasks built from your codes: one on day 3, one on day 7. That’s all.
Sources
- FAA, FAA-S-ACS-1, Aviation Mechanic General, Airframe, and Powerplant Airman Certification Standards, Section III (Powerplant) and Appendix 1.
- FAA, Mechanic Test Generator FAQs (updated 5/22/2023), Oral-related questions and 14 CFR 65.80.
- FAA, Sample Test, Oral and Practical, Section III.
- FAA, FAA-H-8083-32B, Aviation Maintenance Technician Handbook: Powerplant, chapters 1, 2, 3, 4, 6, 7, 8, and 10.
- FAA, FAA-H-8083-31B, Aviation Maintenance Technician Handbook: Airframe, chapter 17 (fire detection).
About this guide: drafted with AI from the FAA sources listed on this page and checked claim by claim against them. Not reviewed by an A&P mechanic or DME. How we make our guides
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