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Free A&P Powerplant practice test

20 original questions on reciprocating engines and ignition systems, taken from the free sample. Each answer includes an explanation and a page reference in FAA-H-8083-32B.

1. What is the purpose of the crankcase?
  1. To store fuel
  2. To house and support the crankshaft and form the engine's foundation
  3. To cool the cylinders
Show answer

B. To house and support the crankshaft and form the engine's foundation The crankcase contains the bearings in which the crankshaft revolves.

Reference: FAA-H-8083-32B, Ch. 1, p. 1-5

2. What is a full-floating piston pin?
  1. A pin free to turn in both the piston and the connecting rod
  2. A pin fixed to the connecting rod
  3. A pin welded to the piston
Show answer

A. A pin free to turn in both the piston and the connecting rod The pin must be held in place so its ends cannot score the cylinder walls.

Reference: FAA-H-8083-32B, Ch. 1, p. 1-13

3. Why do aircraft valves usually use two or more springs?
  1. To reduce valve lift
  2. To prevent surging and give redundancy if one breaks
  3. To make the valve open faster
Show answer

B. To prevent surging and give redundancy if one breaks Each spring vibrates at a different speed, damping surge; multiple springs also protect against breakage.

Reference: FAA-H-8083-32B, Ch. 1, p. 1-21

4. What opens the valves in a reciprocating engine?
  1. Oil pressure only
  2. Cylinder pressure
  3. Cam lobes acting through lifters, pushrods and rocker arms
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C. Cam lobes acting through lifters, pushrods and rocker arms The cam pushes the lifter, the pushrod moves the rocker arm, and the rocker opens the valve.

Reference: FAA-H-8083-32B, Ch. 1, p. 1-19

5. What is the most common engine type in light general aviation aircraft?
  1. Inline inverted
  2. Horizontally opposed
  3. Radial
Show answer

B. Horizontally opposed Small general aviation aircraft use mostly horizontally opposed piston engines.

Reference: FAA-H-8083-32B, Ch. 1, p. 1-1

6. Why is a rich mixture used for takeoff?
  1. To increase fuel economy
  2. To reduce exhaust temperature to zero
  3. To cool the engine and help prevent detonation
Show answer

C. To cool the engine and help prevent detonation Extra fuel absorbs heat during high-power operation.

Reference: FAA-H-8083-32B, Ch. 2, p. 2-4

7. The smaller two-cycle light-sport engines run on what mixture?
  1. Gasoline with 10 percent oil
  2. Pure gasoline, with oil from a sump
  3. Gasoline with 2 percent oil premixed
Show answer

C. Gasoline with 2 percent oil premixed 32B: a mixture of gasoline and 2 percent oil.

Reference: FAA-H-8083-32B, Ch. 11, p. 11-4

8. A light-sport engine's reduction gearbox in 32B drives the propeller at what ratio?
  1. 1.5 to 1
  2. 3 to 1
  3. 2.13 to 1
Show answer

C. 2.13 to 1 32B cites a 2.13:1 reduction ratio.

Reference: FAA-H-8083-32B, Ch. 11, p. 11-9

9. What is engine durability?
  1. The ability to run smoothly at all speeds
  2. The amount of engine life obtained while keeping the desired reliability
  3. The power-to-weight ratio
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B. The amount of engine life obtained while keeping the desired reliability 32B defines durability this way.

Reference: FAA-H-8083-32B, Ch. 1, p. 1-2

10. What is operating flexibility?
  1. Ease of maintenance access
  2. The ability to run smoothly and give desired performance from idle to full power
  3. Engine life between overhauls
Show answer

B. The ability to run smoothly and give desired performance from idle to full power 32B definition.

Reference: FAA-H-8083-32B, Ch. 1, p. 1-3

11. How does a low-tension ignition system differ from a high-tension system?
  1. Low voltage goes to a transformer coil near each spark plug
  2. It uses only one spark plug per cylinder
  3. It needs no breaker points
Show answer

A. Low voltage goes to a transformer coil near each spark plug Voltage is stepped up near the plug, avoiding long high-voltage leads.

Reference: FAA-H-8083-32B, Ch. 4, p. 4-1

12. What is the E-gap in magneto timing?
  1. The gap between breaker points when fully open
  2. The rotor position a few degrees past neutral where the points begin to open
  3. The spark plug electrode gap
Show answer

B. The rotor position a few degrees past neutral where the points begin to open At E-gap the breaker points should just begin to open.

Reference: FAA-H-8083-32B, Ch. 4, p. 4-29

13. What is the purpose of the condenser (capacitor) in a magneto?
  1. To store a spare charge for starting
  2. To prevent arcing at the breaker points and speed up field collapse
  3. To filter radio noise only
Show answer

B. To prevent arcing at the breaker points and speed up field collapse The capacitor absorbs the surge when points open, protecting them and intensifying the spark.

Reference: FAA-H-8083-32B, Ch. 4, p. 4-3

14. Why is a magneto with a broken P-lead dangerous?
  1. It drains the battery
  2. It cannot be grounded, so the engine may fire if the propeller is moved
  3. It will not produce a spark
Show answer

B. It cannot be grounded, so the engine may fire if the propeller is moved An ungrounded ("hot") magneto can fire a cylinder when the prop is turned by hand.

Reference: FAA-H-8083-32B, Ch. 4, p. 4-31

15. What does an impulse coupling do?
  1. Gives a hot, retarded spark for starting by snapping the magneto rotor ahead
  2. Couples the two magnetos together
  3. Advances the timing at high rpm
Show answer

A. Gives a hot, retarded spark for starting by snapping the magneto rotor ahead A spring winds up and releases, spinning the magnet fast at a retarded position during cranking.

Reference: FAA-H-8083-32B, Ch. 4, p. 4-20

16. What is spark plug "reach"?
  1. The voltage the plug can handle
  2. The distance between electrodes
  3. The length of the threaded portion that goes into the cylinder
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C. The length of the threaded portion that goes into the cylinder Using the wrong reach can cause hot spots or poor ignition.

Reference: FAA-H-8083-32B, Ch. 4, p. 4-25

17. How does a "hot" spark plug differ from a "cold" plug?
  1. It fires at a higher voltage
  2. It has a larger electrode gap
  3. It transfers heat to the cylinder head more slowly
Show answer

C. It transfers heat to the cylinder head more slowly Hot plugs have a long insulator nose path; cold plugs move heat away quickly for high-compression engines.

Reference: FAA-H-8083-32B, Ch. 4, p. 4-25

18. What commonly causes lead fouling of spark plugs?
  1. Running the engine too lean at high power
  2. Lead oxide formed from leaded fuel during combustion
  3. Too much oil in the sump
Show answer

B. Lead oxide formed from leaded fuel during combustion Lead forms lead oxide deposits; ethylene dibromide is added as a scavenger.

Reference: FAA-H-8083-32B, Ch. 4, p. 4-34

19. What type of ignition do most turbine engines use?
  1. Battery coil ignition with distributors
  2. High-energy capacitor-discharge ignition with igniter plugs
  3. Magnetos with impulse couplings
Show answer

B. High-energy capacitor-discharge ignition with igniter plugs Exciters store energy in capacitors and discharge it across the igniter.

Reference: FAA-H-8083-32B, Ch. 4, p. 4-43

20. Why must care be taken when working on turbine ignition exciters?
  1. Their high energy and voltage can cause injury or death
  2. They contain radioactive material
  3. They operate at extreme temperatures
Show answer

A. Their high energy and voltage can cause injury or death Caution: activated turbine ignition systems can cause injury or death.

Reference: FAA-H-8083-32B, Ch. 4, p. 4-46

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355 original questions with handbook citations, 385 flashcards, 20 interactive diagrams and timed mocks scored by ACS area. $29 one-time, 14-day refund. The free sample covers reciprocating engines and ignition, with no account or card needed.

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FAQ

Are these the real FAA test questions?

No. They are original questions written from FAA-H-8083-32B and the Aviation Mechanic ACS. They teach the concepts the test covers.

How many questions are in the full kit?

355 original questions (300 practice plus 55 held back for a final mock), 385 flashcards and 20 interactive diagrams.