FAA · Private Pilot Knowledge Test

Private Pilot Aircraft Systems

From the engine to the cockpit: piston engine, ignition, fuel, propeller, electrical, and environmental.

There is no separate Aircraft Systems exam. It is one of the subjects on the Private Pilot Knowledge Test, a single test that covers them all.

The Knowledge Test

60questions
2.5 htime limit
70%to pass

Syllabus

What the test covers

Pocket Pilot teaches Aircraft Systems in seven lessons, about 52 minutes of reading in all.

01
Airframe & Flight Controls
8 min
Major structural components · Construction types · Primary flight controls · Secondary flight controls · Landing gear · Control positions when taxiing in wind · Composite vs. metal: what changed
02
The Four-Stroke Piston Engine
8 min
The Otto cycle: four strokes, two revolutions · Why horizontally opposed? · Engine cooling · The oil system · Operating instruments · Detonation and pre-ignition · Power and altitude · Turbocharging: a different story · Engine handling fundamentals · Time between overhaul (TBO)
03
Ignition & the Magneto System
6 min
Why dual ignition? · What a magneto actually is · The mag switch · The mag check, at every runup · Spark plug fouling · Impulse coupling and starting · "Magneto" emergencies · Modern alternatives
04
Fuel Systems & Mixture
10 min
Avgas: what's in the tank · Density and weight · Fuel system architecture: gravity vs. pump · Fuel tanks and selector · Fuel quantity gauges · Sumping fuel · Mixture control · The primer · Carburetor vs. fuel injection · Carburetor icing · Refueling discipline
05
Propellers
6 min
Fixed-pitch vs. constant-speed · How a constant-speed prop works · Setting power: the right sequence · Propeller blade as airfoil · P-factor revisited · Critical engine on twins · Propeller efficiency · Propeller hazards · Propeller maintenance
06
Electrical System
7 min
Architecture in a light single · Battery · The starter · Alternator · The master switch · Ammeter vs. loadmeter · Buses · The avionics master · Circuit breakers vs. fuses · Alternator failure in flight · Static electricity and bonding · Day-VFR electrical reality check
07
Environmental & Anti-Ice Systems
7 min
Cabin heat and its hidden hazard · Cabin ventilation · Pitot heat · Carburetor heat · Anti-ice vs. de-ice: the difference · Certification for flight into known icing (FIKI) · De-ice systems explained · Propeller anti-ice · Windshield anti-ice / defog · Oxygen systems · Pressurization (for context)

Format

How the test works

The Private Pilot Knowledge Test, often called the written, is one multiple-choice test of 60 questions drawn from every area of the FAA's Airman Certification Standards. Aircraft Systems questions are mixed in with the rest.

You have 2.5 hours, and you need 70% to pass, which is 42 correct answers.
You take it at an approved testing center, once your instructor has endorsed you for it.
A pass is valid for 24 calendar months, and you need to pass your checkride within that time.

In Pocket Pilot you can practice Aircraft Systems on its own, from a growing question bank, then sit a full 60-question mock exam that mixes every subject, timed like the real test.

Sample questions

Try three test questions

From the Pocket Pilot Aircraft Systems question bank, each with the app's explanation and the source it cites.

01 / 03
During preflight sumping you expect blue 100LL, but the sample is nearly clear and smells of kerosene. This most likely indicates:
1. AJet fuel contamination: do not fly until the fuel system is drained and inspected
2. BNormal fuel with the dye faded
3. CWater contamination
4. DAutomotive gasoline from an STC operation
Show the answerHide the answer
Answer A. Jet A is straw-colored to clear and smells of kerosene. A piston engine run on jet fuel will detonate and can be destroyed within minutes at takeoff power. Misfueling is a known killer: verify grade at every fueling and sump afterward.
Source
FAA-H-8083-25C, Chapter 7
Lesson
Fuel Systems & Mixture
02 / 03
On most single-engine constant-speed propeller installations, a total loss of governor oil pressure causes the propeller to:
1. AFeather
2. BGo to the high-pitch, low-RPM stop
3. CGo to the low-pitch, high-RPM stop
4. DStop rotating
Show the answerHide the answer
Answer C. Oil pressure drives the blades toward high pitch; the spring or counterweights return them to low pitch (high RPM) when pressure is lost. Multi-engine propellers are typically the opposite, failing to feather to reduce drag.
Source
FAA-H-8083-25C, Chapter 7
Lesson
Propellers
03 / 03
In cruise flight, the zero-centered ammeter shows a steady discharge (needle left of zero). This indicates:
1. AThe battery is fully charged
2. BNormal operation at high RPM
3. CThe alternator is no longer supplying power and the battery is feeding the electrical load
4. DThe voltage regulator is overcharging the battery
Show the answerHide the answer
Answer C. A discharge indication means the alternator output is insufficient or offline and the battery is supplying the bus. Reduce electrical load, attempt an alternator reset per the POH, and plan to land before the battery is exhausted.
Source
FAA-H-8083-25C, Chapter 7
Lesson
Electrical System