Operation of Systems (ACS)

Question 1

(Operation of Systems)
What are the primary flight controls?

Answer 1

Three primary flight controls are the:

Ailerons: roll

Rudder: yaw

Elevator: pitch

The control surfaces that allow the pilot to directly control pitch, bank, and yaw.

Question 2

(Operations of Systems)
What are the secondary flight controls?

Answer 2

control surfaces that do not directly affect the three primary axis of movement. They do greatly enhance the capabilities of an aircraft.

Secondary flight control:

Wing flaps, leading edge devices, trim systems, or spoilers.

Question 3

(Operations of Systems)
What are the four parts that make up the four stroke cycle?

Answer 3

Suck - Intake
Squeeze - Compression
Bang -
Blow -

-In the intake stage the piston travels down as air and fuel enters the cylinder.
-When the piston reaches the bottom of travel and starts coming back up the engine enters the compression stage. The piston compresses the air fuel mixture to increase the strength of the combustion.
-The combustion happens in the power stage. As the spark plugs ignite the compressed air fuel mixture the resulting pressure pushes the piston down which turns the cam shaft which powers the propeller and the alternator.
-The exhaust phase where the exhaust valve opens up and the waste gasses from the combustion are expelled.

The cycle repeats these steps.

Question 4

(Operations of Systems)
How do carbureted engines and fuel injected engines work?

Answer 4

Carbureted engines:
-A carburetor is a chamber that uses the venturi effect to create an accelerated vacuum. with which fuel is sucked into the chamber and mixed with air.
-The amount of air sent to the engine is determined by the throttle. The amount of fuel to be mixed with the air is set with the mixture control. The fuel air mixture is sent via the induction system to the cylinders where it is introduced during the intake phase of the four stroke cycle.

Fuel injected engines
-A fuel air control unit controls the mixture of fuel and air. Note that it is sometimes called a servo regulator depending on the manufacturer.
-The big difference here is the air and fuel are not mixed together in the fuel air control unit. Instead the fuel air control unit compares the air flow control of the throttle and then meters the correct amount of fuel needed.
-The fuel does not combine with the air until just prior to hitting the cylinder.
-An engine driven fuel pump is what carries fuel and primes the engine. There is a fuel manifold that distributes fuel to each cylinder via discharge nozzles.

Question 5

(Operations of Systems)
What are the positives and negatives of a carbureted vs fuel injected engine?

Answer 5

carbureted characteristics:
-Manual priming is required via a pump in the cockpit.
-Easy to hot start. The carburetor has little difficulty pulling in required fuel air mixture for restart.
-Less fuel efficient overall
-Suffers from icing

Injected characteristics:
-Electric fuel pump is used to prime. Easier to prime but easy to over prime.
-Fuel is not combined until just before release into the cylinder. so the fuel manifold have pure fuel in them. When it is hot and the engine is stopped, fuel can vaporize in the manifold lines creating pockets of air in the lines. This creates a situation where air is being mixed with air in the cylinder.
-More precise metering of fuel into the fuel air mixture.
-Biggest benefit is it does not ice nearly as easily as carburetors do.

Question 6

(Operations of Systems)
What is the purpose of engine oil?

Answer 6

The oil in an aircrafts engine does several things including:

-Lubricate the engine components.
-Cools the engine. By reducing the amount of friction that the moving components have on each other, and by displacing the heat due to oil liquid nature it can be replaced by cooler oil.
-creates a seal between the pistons and the cylinder.
-Cleans the engine by carrying the byproducts of combustion and metal shavings and other impurities while the oil circulates.

Question 7

(Operations of Systems)
How does the ignition system work?

Answer 7

Does the engine stop if there is an electrical failure? No.

-The ignition system consists of magnetos, spark plugs, and a starter motor.
-Magnetos power the spark plugs.
-Magnetos ignite the fuel air mixture in the cylinders and the cylinders power the magnetos.
-Since the magnetos generate their own power through mechanical means their not connected to the electrical system at all. This is why the engine will continue to run despite an electrical failure.
-there are usually 2 magnetos for redundancy. There are 2 spark plugs per cylinder which is for redundancy and better fuel burn in the cylinders.
-The starter motor is powered by the aircraft battery and drives the engine enough for the air fuel mixture to enter the cylinders and for the spark plugs to fire.

Question 8

(Operations of Systems)
Why do we test the magnetos before flight?

Answer 8

When the ignition switch is moved from both to left or right magneto we want to see a drop in RPM since cylinders don’t burn fuel as efficiently with one spark plug. If there is no drop there might be an electrical short in the cables causing both magnetos to run regardless of the ignition switch.

Fouled spark plugs are also a reason for magnetos coming back with a wrong RPM.

Question 9

(Operations of Systems)
How can spark plugs be defouled in flight?

Answer 9

Lean the mixture and running the engine at around 2,000 RPM for 30 seconds.

Question 10

(Operations of Systems)
What are the power systems in your aircraft?

Answer 10

Ask Chance and look into the POH.

Question 11

(Operations of Systems)
What indication should the ameter read after engine start?

Answer 11

the main battery powers the starter motor which takes a lot of power to do. After starting the engine the alternator will start to power the electrical system and recharge the battery. you want to see that the stand by battery and main battery have positive indicators. This means they are receiving positive charge and are not expending more energy then they are giving.

If there is a negative charge on the ground it could be because the RPM is not high enough to provide charge to the alternator.

In flight there is something wrong with an alternator and a landing should be planned soon.

Question 12

(Operations of Systems)
When flying on a cold day and exhaust can be smelled inside the cabin; what is happening?

Answer 12

The most likely thing that happened is that the cabin heat system has been contaminated. There is a shroud that encompasses part to the exhaust system. The heat from the exhaust system is taken and distributed to the cabin. If there is a crack in the shroud though carbon monoxide poisoning is likely. Shut off the heat and vent the cabin as best as possible. look for a suitable landing immediately.

Question 13

(Operations of Systems)
What is the difference between de-icing and anti-icing equipment?

Answer 13

de-icing equipment undoes icing that has already accumulated on parts of the aircraft.
-inflatable leading edge boots and weeping wing systems.

Anti-Icing equipment prevents ice from forming in the first place.
-Pitot heat, alternate air sources, carburetor heat, and wind shield defrosters are all examples of anti-icing equipment.

Question 14

(Operations of Systems)
What are the pitot static instruments?

Answer 14

The pitot static instruments are the ones that deal with pressure.
-Altimeter, the vertical speed indicator, airspeed indicator.
-The only instrument that uses the pitot tube is the airspeed indicator.
-Each uses ambient pressure from the static ports on the sides of the aircraft.

Question 15

(Operations of Systems)
How does the Altimeter work?

Answer 15

How the ambient pressure compares to standard. From that we can estimate our height above sea level. Essentially the altimeter acts as an aneroid barometer that measures units of pressure instead of increments of height.

The ambient pressure from the static port is piped into the sealed altimeter casing. inside the casing are thin accordian like things called aneroid wafers that have been pressurized and sealed at standard pressure (29.92). Through a series of gears the stack of wafers is connected to the altimeters altitude pointers. if the ambient pressure from the static port decreases the wafers expand moving the pointers clockwise.

Sensitive altimeters are altimeters with an increased number of aneroid wafers making them more precise.
Colsman window is used to adjust the pressure setting.

For example if the ambient pressure from the static port decreases the wafers expand, moving the pointers clockwise which is to be expected as pressure decreases with altitude. Think of how a weather balloon expands as it ascends. If the ambient pressure increases like in a descent that compresses the wafers which decreases the indicated altitude.

Question 16

(Operations of Systems)
Why does an altimeter not always accurately display true altitude?

Answer 16

When we’re flying we want to know true altitude.
- True altitude: the altitude of the aircraft above sea level (airport, obstacle, and terrain altitudes are listed in height above sea level).

The main drawback of pressure altimeters are that they can only give an approximation of true altitude which is known as indicated altitude.

The factors the cause the discrepancy of indicated altitude reporting are:
-Nonstandard pressure: the altimeter needs to be updated to the correct pressure setting in order for it to read correctly. A change of 0.1 inches of mercury is equivalent to 100 feet of altitude.
-Nonstandard temperature. Hot to cold look out below

Question 17

(Operations of Systems)
When flying from an area of relatively high pressure to an area of relatively low pressure without changing the altimeter setting, how does your true altitude change?

Answer 17

High to low look out below.

The colesman knob acts as a clock adjustment. if you rotate it counter clockwise both the pressure setting and the indicated altitude decrease. If you rotate it clockwise both the pressure setting and the indicated altitude increases.

If youre flying at 5,000’ indicated with a setting of 30.00 inches of mercury, but the setting should be 29.80. What happens when the knob gets rotated counter clockwise to make that adjustment? The altimeter will adjust and indicate a lower altitude. 4,800’ is the real altitude.

Question 18

(Operations of Systems)
What altimeter settings do you use for cruise flight below and above 18,000’ MSL?

Answer 18

Change the setting to 29.92 (FAR 91.121) above 18,000’.

When flying below the altimeter setting must be changed to the current altimeter setting of a station within 100 miles. If there isn’t a station within 100 miles then use a current altimeter setting of an appropriate station.

Question 19

(Operations of Systems)
How does the airspeed indicator work?

Answer 19

The airspeed indicator is the only pitot static instrument that uses the pitot tube as well as the static port.
This is because we must compare these two sources to find out our indicated airspeed.

the pitot tube registers ram air pressure from the relative wind caused by the aircraft moving through the air. This ram air pressure is called dynamic air pressure. The pitot tube uses the dynamic air and compares it with the ambient air pressure from the static port. The combination of these two pressures is known as total pressure.

Subtracting the static pressure from the total pressure we can determine the dynamic pressure which is what is needed to determine airspeed. The airspeed indicator accomplishes this. A static pressure line leading to the airspeed indicators casing allows the ambient pressure from the static port to fill the casing. The total pressure from the pitot tube fills an expandable diaphragm that sits inside the casing. As the aircraft flies faster the increased dynamic pressure inflates the diaphragm. The static pressure inside the diaphragm inflates the diaphragm but the static pressure inside the casing puts pressure on the outside in equal amounts. This equilibrium that is found by the two static pressures leaves only the dynamic pressure acting and making differences.

Diaphragm inflates the airspeed indicator reads a higher airspeed.

Question 20

(Operations of Systems)
How does the vertical speed indicator work?

Answer 20

The third and final pitot static instrument is the vertical speed indicator. VSI uses pressure comparison. How fast we are climbing or descending. Inside of the instrument there is a diaphragm similar to the one in the airspeed indicator. It only contains static pressure though. The VSI case has static pressure, the diaphragm has static pressure, but the case also has a calibrated leak.

The calibrated leak in the case allows the static pressure in the case to adjust to the ambient pressure felt by the changing altitude. The less the pressure the more the diaphragm can expand and indicate a rise in altitude. the higher the pressure the more compressed the diaphragm and the lower the indicated drop in height. This allows for the VSI to show a rise and fall in altitude.

The VSI shows trends and is not completely accurate. There is a delay.

Question 21

(Operations of Systems)
How do pitot static port blockages affect instrument readings?

Answer 21

Pitot tube blockage:
-if only the ram air inlet gets blocked the pitot tube will no longer register dynamic pressure only static pressure through the drainage hole. This will cause the Airspeed indicator to read zero.
-If the ram air inlet and the drainage hole is blocked the pressure inside the airspeed indicator becomes fixed at whatever existed at the time of the blockage and the instrument gets stuck at whatever speed. The instrument then becomes an altimeter of sorts. the needle will shift based on height/changing pressure instead of airspeed. Don’t be fooled it is not an altimeter.

Static port blockage:
-The altimeter will be stuck at whatever it was registering at the time of blockage.
-The VSI will be fixed at zero.
-The airspeed indicator will look like it is still working but it won’t be accurate.

Question 22

(Operations of Systems)
What is the purpose of the alternate static system

Answer 22

the backup for when the static port is blocked. There will be a cockpit control that opens the alternate static source. The alternate port itself will also be in the cockpit. This will result in deviations in instrument readings. They’ll work though.

Breaking the glass of one of the instruments can also create an alternate static port.

Question 23

(Operations of Systems)
what instruments work on gyroscopic principles?

Answer 23

The attitude indicator
The heading indicator
The turn coordinator

A gyroscopic instrument measures the aircrafts rotation around the three axis of movement.

Question 24

(Operations of Systems)
What two gyroscopic principles do aircraft instruments use?

Answer 24

Rigidity in space: the disc stays in its original plane as it moves.
Gyroscopic precession: a force is felt 90 degrees away from the original area in the discs rotation.

Question 25

(Operations of Systems)
What causes the gyroscope to spin?

Answer 25

gyroscopic systems are powered by a vacuum system, an electrical motor, a venturi system, or a combination of these.

Typically the attitude and heading indicator use a vacuum system. An engine driven motor that sucks air through a tube. the air is cleaned through a filter and sent to the gyroscope that have veins to deliver the air. A suction gauge allows the pilot to ensure the vacuum system is sucking enough air to spin the gyros fast enough.

Turn coordinators are usually powered by an electric motor but it can be powered by a vacuum system in older aircraft.

Question 26

(Operations of Systems)
How does the attitude indicator work?

Answer 26

The gyro in the attitude indicator is mounted horizontally, parallel to the ground. It is mounted in a double gimble which allows for rotation around the pitch and role axis. Once the gyro starts spinning the gyro will want to maintain its original orientation which is parallel to the ground. Attached to the artificial horizon, so the horizon bar actually stays in place as the aircraft pitches and banks around it. The indicator is fixed to the instrument.

Question 27

(Operations of Systems)
Are there any limitations associated with the attitude indicator?

Answer 27

No it is a very reliable instrument.
-If you accelerate or decelerate in flight the attitude indicator might show a increase or decrease in pitch. Its not a large change.

Question 28

(Operations of Systems)
How does the heading indicator work?

Answer 28

unlike the attitude indicator the heading indicators gyro is mounted vertically. meaning the rotation is around the vertical axis. We want to measure the yaw of the aircraft. The outer gimble system rotates around the yaw axis which is connected via gears to the face of the heading indicator. As the aircraft turn the gyro stays in place while the aircraft yaws around it. This rotates the face of the heading indicator. The inner gimble allows the gyro to stay fixed as the aircraft banks. Ensuring that we are measuring the nose swinging around the horizon regardless of attitude.

Adjust the heading indicator to the magnetic heading that is being flown.

Question 29

(Operations of Systems)
Are there any limitations or errors associated with the heading indicator.

Answer 29

Yes. Many.

-Correcting the heading must be done throughout the flight. Precession will cause the heading indicator to drift from displaying the correct heading. Adjust every 15 minutes. 3 degrees every 15 minutes is normal.

Question 30

(Operations of Systems)
How does the turn coordinator work?

Answer 30

Third and final gyroscopic instrument. The gyro in the turn coordinator spins in the plane of the longitudinal axis which goes from nose to tail. The gimble itself is not aligned entirely with the longitudinal axis. Rather it is canted 30 degrees up. This allows the instrument to show the rate of roll and the rate of turn. By using precession.

As the aircraft rolls or yaws it creates a force on the gyro in the horizontal plane. Due to precession this force acts 90 degrees from the horizontal plane. causing the gimble to rotate around the horizontal axis. When entering a turn the aircrafts roll deflects the turn coordinators little airplane in the direction of the turn. The quicker you bank the more deflection there will be. Once the bank is consistent the turn coordinator will give the rate of turn.

Question 31

(Operations of Systems)
How does the magnetic compass work?

Answer 31

a sensing magnet associated with north and south magnets that is floated in fluid allowing the magnets to free float and adjust to the magnetic north and south. A compass card is attached that is graduated and marked with the cardinal directions.

Question 32

(Operations of Systems)
What are the limitations and errors of the magnetic compass?

Answer 32

Turning error:
UNOS: undershoot north, overshoot south

Acceleration error:
ANDS: accelerate north, decelerate south

When flying close to the north or south magnetic poles the compass will be unusable due to the bending of the magnetic field.

Question 33

(Operations of Systems)
What is compass oscillation error?

Answer 33

Oscillation error is simply the compass being jostled around too much to be read too much?

Question 34

(Operations of Systems)
What is compass deviation error?

Answer 34

Deviation is caused by magnetic interference from the aircraft itself. When the compass is installed in the aircraft a mechanic will compare the compass reading with the known magnetic headings while the aircraft is on the ground with powered up instruments. Any differences with the compass and the actual magnetic heading will be written on a compass deviation card that is fixed to the compass.

Question 35

(Operations of Systems)
What is compass variation error?

Answer 35

Variation error is the difference between magnetic north and true north. Since in most places they don’t line up.

Question 36

(Operations of Systems)
How is the compass variation error depicted on a sectional chart?

Answer 36

via Isogonic lines

If the variation is east, subtract it to get true heading
If the variation is west, add it to get true heading