*4A Airplane Systems - Aircraft and Engine Operations

Question 0

1. What are the four main control surfaces and what are their functions?
   (FAA-H-8083-25)

Answer 0

Elevators—The elevators control the movement of the airplane about its lateral axis. This motion is called pitch.
Ailerons—The ailerons control the airplane’s movement about its longitudinal axis. This motion is called roll.
Rudder—The rudder controls movement of the airplane about its vertical axis. This motion is called yaw.
Trim Tabs—Trim tabs are small, adjustable hinged-surfaces on the aileron, rudder, or elevator control surfaces. They are labor-saving devices that enable the pilot to release manual pressure on the primary control.

Question 1

2. How are the various flight controls operated?

AFM

Answer 1

The flight control surfaces are manually actuated through use of either a rod or cable system. A control wheel actuates the ailerons and elevator, and rudder/brake pedals actuate the rudder.

Question 2

3. What are flaps and what is their function?

FAA-H-8083-25

Answer 2

The wing flaps are movable panels on the inboard trailing edges of the wings. They are hinged so that they may be extended downward into the flow of air beneath the wings to increase both lift and drag. Their purpose is to permit a slower airspeed and a steeper angle of descent during a landing approach. In some cases, they may also be used to shorten the takeoff distance.

Question 3

4. Describe the landing gear system on this airplane.

AFM

Answer 3

The landing gear consists of a tricycle-type system utilizing two main wheels and a steerable nosewheel. Tubular spring steel main gear struts provide main gear shock absorption, while nose gear shock absorption is provided by a combination air/oil shock strut.

Question 4

5. Describe the braking system on this aircraft. (AFM)

Answer 4

Hydraulically actuated disc-type brakes are utilized on each main gear wheel. A hydraulic line connects each brake to a master cylinder located on each pilot’s rudder pedals. By applying pressure to the top of either the pilot’s or copilot’s set of rudder pedals, the brakes may be applied.

Question 5

6. How is steering accomplished on the ground? (AFM)

Answer 5

Light airplanes are generally provided with nosewheel steering capabilities through a simple system of mechanical linkage connected to the rudder pedals. When a rudder pedal is depressed, a spring-loaded bungee (push-pull rod) connected to the pivotal portion of a nosewheel strut will turn the nosewheel.

Question 6

7. What type of engine does your aircraft have?

AFM

Answer 6

A horizontally opposed four-cylinder, overhead-valve, air-cooled, carbureted engine. The engine is manufactured by Lycoming and rated at 110 HP.

Question 7

8. What four strokes must occur in each cylinder of a typical four stroke engine in order for it to produce full power?
   (FAA-H-8083-25)

Answer 7

The four strokes are:
Intake—fuel mixture is drawn into cylinder by downward stroke
Compression—mixture is compressed by upward stroke
Power—spark ignites mixture forcing piston downward and producing power
Exhaust—burned gases pushed out of cylinder by upward stroke

Question 8

9. What does the carburetor do?

FAA-H-8083-25

Answer 8

Carburetion may be defined as the process of mixing fuel and air in the correct proportions so as to form a combustible mixture. The carburetor vaporizes liquid fuel into small particles and then mixes it with air. It measures the airflow and meters fuel accordingly.

Question 9

10. How does the carburetor heat system work? (AFM)

Answer 9

A carburetor heat valve, controlled by the pilot, allows unfiltered, heated air from a shroud located around an exhaust riser or muffler to be directed to the induction air manifold prior to the carburetor. Carburetor heat should be used anytime suspected or known carburetor icing conditions exist.

Question 10

11. What change occurs to the fuel/air mixture when applying carburetor heat?
    (FAA-H-8083-25)

Answer 10

Normally, the introduction of heated air into the carburetor will result in a richer mixture. Warm air is less dense, resulting in less air for the same amount of fuel.

Question 11

12. What does the throttle do?

FAA-H-8083-25

Answer 11

The throttle allows the pilot to manually control the amount of fuel/air charge entering the cylinders. This in turn regulates the engine speed and power.

Question 12

13. What does the mixture control do?

FAA-H-8083-25

Answer 12

It regulates the fuel-to-air ratio. All airplane engines incorporate a device called a mixture control, by which the fuel/air ratio can be controlled by the pilot during flight. The purpose of a mixture control is to prevent the mixture from becoming too rich at high altitudes, due to decreasing air density. It is also used to lean the mixture during cross-country flights to conserve fuel and provide optimum power.

Question 13

14. Describe a fuel injection system installed in some aircraft.
    (FAA-H-8083-25)

Answer 13

The fuel injection system injects fuel directly into the cylinders, or just ahead of the intake valve. It incorporates six basic components:

1. Engine-driven fuel pump—provides fuel under pressure from the fuel tank to the fuel/air control unit.
2. Fuel/air control unit—meters fuel based on the mixture control setting and sends it to the fuel manifold valve at a rate controlled by the throttle.
3. Fuel manifold valve—distributes fuel to the individual fuel discharge nozzles.
4. Discharge nozzles—located in each cylinder head, these inject the fuel/air mixture at the precise time for each cylinder directly into each cylinder intake port.
5. Auxiliary fuel pump—provides fuel under pressure to fuel/air control unit for engine starting and/or emergency use.
6. Fuel pressure/flow indicators—measures metered fuel pressure/flow.

Question 14

15. What type of ignition system does your airplane have?

AFM

Answer 14

Engine ignition is provided by two engine-driven magnetos, and two spark plugs per cylinder. The ignition system is completely independent of the aircraft electrical system. The magnetos are engine-driven self-contained units supplying electrical current without using an external source of current. However, before they can produce current, the magnetos must be actuated, as the engine crankshaft is rotated by some other means. To accomplish this, the aircraft battery furnishes electrical power to operate a starter which, through a series of gears, rotates the engine crankshaft. This in turn actuates the armature of the magneto to produce the sparks for ignition of the fuel in each cylinder. After the engine starts, the starter system is disengaged, and the battery no longer contributes to the actual operation of the engine.

Question 15

16. What are the two main advantages of a dual ignition system?
    (FAA-H-8083-25)

Answer 15

a. Increased safety: in case one system fails the engine may be operated on the other until a landing is safely made.
b. More complete and even combustion of the mixture, and consequently, improved engine performance; i.e., the fuel/air mixture will be ignited on each side of the combustion chamber and burn toward the center.

Question 16

17. What type of fuel system does your aircraft have?

AFM

Answer 16

The fuel system is a “gravity feed” system. Using gravity, the fuel flows from two wing fuel tanks to a fuel shutoff valve which, in the “on” position, allows fuel to flow through a strainer and then to the carburetor. From there, the fuel is mixed with air and then flows into the cylinders through the intake manifold tubes.

Question 17

18. What purpose do fuel tank vents have?

AFM

Answer 17

As the fuel level in an aircraft fuel tank decreases, a vacuum would be created within the tank which would eventually result in a decreasing fuel flow and finally engine stoppage. Fuel system venting provides a way of replacing fuel with outside air, preventing formation of a vacuum.

Question 18

19. Does your aircraft use a fuel pump?

AFM

Answer 18

No, the fuel is transferred from the wing tanks to the carburetor by the “gravity feed” system. The gravity system does not require a fuel pump because the fuel is always under positive pressure to the carburetor. For some aircraft where for some reason it is not possible to place the wings above the carburetor, or for which a greater pressure is required than what gravity feed can supply, it is necessary to utilize engine-driven fuel pumps and auxiliary fuel pumps as backups.

Question 19

20. What type fuel does your aircraft require (minimum octane rating and color)?
    (AFM)

Answer 19

The approved fuel grade used is 100LL and the color is blue.

Question 20

21. Can other types of fuel be used if the specified grade is not available?
    (FAA-H-8083-25)

Answer 20

Airplane engines are designed to operate using a specific grade of fuel as recommended by the manufacturer. If the proper grade of fuel is not available, it is possible, but not desirable, to use the next higher grade as a substitute. Always reference the aircraft’s AFM or POH.

Question 21

22. What color of dye is added to the following fuel grades: 80, 100, 100LL, Turbine?
    (FAA-H-8083-25)

Answer 21

Grade - Color
80 - Red
100 - Green
100LL - Blue
Jet A - Colorless or Straw

Question 22

23. If a non-turbine piston engine powered airplane is accidentally fueled with JET-A fuel, will it start?
    (FAA-H-8083-25)

Answer 22

Yes; a piston engine operating on jet fuel may start, run, and power the airplane, but will fail because the engine has been destroyed from detonation. Jet fuel can be identified by its distinctive kerosene scent and oily feel when rubbed between the fingers.

Question 23

24. What is the function of the manual primer, and how does it operate?
    (AFM)

Answer 23

The manual primer’s main function is to provide assistance in starting the engine. The primer draws fuel from the fuel strainer and injects it directly into the cylinder intake ports. This usually results in a quicker, more efficient engine start.

Question 24

25. Describe the electrical system on your aircraft.

AFM

Answer 24

Electrical energy is provided by a 28-volt, direct-current system powered by an engine-driven 60-amp alternator and a 24-volt battery.

Question 25

26. How are the circuits for the various electrical accessories within the aircraft protected?
    (AFM)

Answer 25

Most of the electrical circuits in an airplane are protected from an overload condition by either circuit breakers or fuses or both. Circuit breakers perform the same function as fuses except that when an overload occurs, a circuit breaker can be reset.

Question 26

27. The electrical system provides power for what equipment in an airplane?
    (AFM)

Answer 26

Normally, the following:

a. Radio equipment
b. Turn coordinator
c. Fuel gauges
d. Pitot heat
e. Landing light
f. Taxi light
g. Strobe lights
h. Interior lights
i. Instrument lights
j. Position lights
k. Flaps (maybe)
l. Stall warning system (maybe)
m. Oil temperature gauge
n. Electric fuel pump (maybe)

Question 27

28. What does the ammeter indicate?

AFM

Answer 27

The ammeter indicates the flow of current, in amperes, from the alternator to the battery or from the battery to the electrical system. With the engine running and master switch on, the ammeter will indicate the charging rate to the battery. If the alternator has gone off-line and is no longer functioning, or the electrical load exceeds the output of the alternator, the ammeter indicates the discharge rate of the battery.

Question 28

29. What function does the voltage regulator have?

Answer 28

The voltage regulator is a device which monitors system voltage, detects changes, and makes the required adjustments in the output of the alternator to maintain a constant regulated system voltage. It must do this at low RPM, such as during taxi, as well as at high RPM in flight. In a 28-volt system, it will maintain 28 volts ±0.5 volts.

Question 29

30. Why is the generator/alternator voltage output slightly higher than the battery voltage?
    (FAA-H-8083-25)

Answer 29

The difference in voltage keeps the battery charged. For example, a 12-volt battery would be supplied with 14 volts.

Question 30

31. How does the aircraft cabin heat work?

AFM

Answer 30

Fresh air, heated by an exhaust shroud, is directed to the cabin through a series of ducts.

Question 31

32. How does the pilot control temperature in the cabin?

AFM

Answer 31

Temperature is controlled by mixing outside air (cabin air control) with heated air (cabin heat control) in a manifold near the cabin firewall. This air is then ducted to vents located on the cabin floor.

Question 32

33. What are the five basic functions of aircraft engine oil?
    (FAA-H-8083-25)

Answer 32

Lubricates—the engine’s moving parts
Cools—the engine by reducing friction
Removes—heat from the cylinders
Seals—provides a seal between the cylinder walls and pistons
Cleans—by carrying off metal and carbon particles and other oil contaminants