Aircraft Instrument Systems Flashcards

1
Q

Where are the system descriptions found for annunciator indications and the meaning of the associated warnings, cautions, and advisory lights?

A

In the POH/AFM and the ICAs.

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2
Q

What fluid is used in an aircraft magnetic compasss?

A

A special water-clear fluid similar to kerosine.

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3
Q

What is the maximum amount of deviation error allowed when a magnetic compass is installed in an aircraft?

A

10 degrees.

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4
Q

Where should the compass correction card be placed?

A

In plain sight of the pilot, near the compass.

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5
Q

What is the difference between variation and deviation in a compass system?

A

compass variation is caused by the difference between the earth’s magnetic and geographic poles. Aeronautical charts display magnetic variation. Compass deviation is caused by all other magnetic fields aside from the earth’s magnetic and geographic poles. Deviation may be caused by magnetic fields in the aircraft.

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6
Q

What error is corrected when an aircraft compass is swung?

A

Deviation error.

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7
Q

What is done to a compass to correct for deviation error?

A

The compensating magnets in the compass are adjusted to minimize the effect of outside magnetic fields.

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8
Q

Where on an airport is a compass rose located?

A

At a location where there is little traffic and the area is free from magnetic interference caused by electrical power lines or buried pipes.

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9
Q

What are the three fundamental pressure-sensing mechanisms used in aircraft instrument systems?

A

The Bourdon tube, the diaphragm or bellows, and the solid-state sensing device.

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10
Q

What basic mechanism is used to measure oil, fuel, and oxygen pressures?

A

The bourdon tube.

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11
Q

What mechanical means is used to measure pressure in an airspeed indicator?

A

A diaphragm.

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12
Q

A failure of an airspeed indicator needle to move is likely caused by what problem?

A

A blockage in the pitot head will prevent the creation of a differential pressure.

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13
Q

What mechanical means can be used to measure oil temperature?

A

A fluid filled, sealed system comprising of a bulb and capillary tube connected to a Bourdon tube. As temperature increasses, the volume of the fluid increases and expands the Bourdon tube, which is connected to an indicator dial.

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14
Q

How does a thermocouple measure temperature?

A

The unit is comprised of two unlike metals. As temperature increases, a small voltage is produced and sent to a temperature indicator. The higher the temperature, the higher the voltage.

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15
Q

Why is the length of a thermocouple lead important?

A

Thermocouple accuracy is dependent on the resistance of the circuit. Lead lengths are designed for specific installations and should never be altered.

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16
Q

What type of electrical circuit is used to measure small changes of resistance in an electrical resistance temperature probe?

A

A wheatstone-bridge circuit.

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17
Q

What type of system is used to indicate the position of the wing flaps?

A

Usually a resistance-type remote-indicating system such as the DC Selsyn system.

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18
Q

What information is shown by the wing flap position indicator?

A

The number of degrees the flaps are lowered.

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19
Q

What are the gyroscopic instruments that are connected to the low-pressure pneumatic system of an aircraft?

A

Heading indicator
Attitude indicator
Turn-and-slip indicator

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20
Q

What device is used with a wet-pump vacuum system to prevent oil from getting into the deicer boots?

A

An oil separator.

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21
Q

What are two types of filters used with a pressure system for gyros?

A

A pump inlet filter and an inline filter.

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22
Q

What type of filter is used with a vacuum system for gyros?

A

A central air filter.

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23
Q

What may be causing an attitude indicator to not properly erect or display?

A

Gyroscopes are dependent on achieving and maintaining proper rotational speed. Failure to do so may be caused by low vacuum created by the vacuum system or motor failure in an electrically-driven gyroscope.

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24
Q

What type of direction-finding compass has no moving parts and easily integrates with digital systems?

A

Solid state magnetometers.

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25
Q

How does a flux gate compass operate?

A

The flux gate compass consists of a very magnetically permeable circular segmented core from called a spider. The earth’s magnetic field flows through this iron core and varies its distribution through segments of the core as the flux valve is rotated via the movement of the aircraft. Pickup coil windings are located on each of the core’s spider legs that are positioned 120° apart. The signal from the flux gate is passed to the flight deck via an autosyn transmitter.

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26
Q

What two types of pumps are used in the low-pressure pneumatic system?

A

A dry-type and a wet-type air pump.

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27
Q

What are the vanes of a wet-type air pump made of?

A

Steel.

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28
Q

What are the vanes of a dry-type air pump made of?

A

Carbon.

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29
Q

How are the vanes of a wet-type air pump lubricated?

A

With engine oil directed into the pump through a small hole in the base of the pump.

30
Q

why is it important to use the correct gasket when replacing a wet-type air pump?

A

The gasket must have a hole through which the pump lubricating oil can flow.

31
Q

Why do dry-type air pumps not need to be lubricated?

A

The special carbon material of which the vanes are made wears away in microscopic amounts to provide the needed lubrication.

32
Q

What must be done to the gyro pressure system if a dry-type air pump fails?

A

All of the filters must be replaced to prevent any debris from the pump vanes getting into the gyro instruments.

33
Q

Who is authorized to perform the altimeter test to determine the accuracy of the altimeter?

A

The manufacturer of the aircraft on which the tests are conducted, or a certificated repair station properly equipped and authorized to perform the test?

34
Q

Where are the requirements for the alitmeter system found?

A

14 CFR Part 43, Appendix E.

35
Q

How often should an altimeter be checked if it is installed in an aircraft used in IFR flight?

A

Every 24 calendar months.

36
Q

How much difference is allowed between the altitude indication on the automatic pressure altitude reporting equipment and that on the altimeter?

A

125 feet.

37
Q

To what altitude must altimeters be tested?

A

To the highest altitude the aircraft will be flown on IFR flight.

38
Q

What record must be made of a test of an altimeter?

A

The aircraft permanent maintenance record must show the date, the maximum altitude to which the altimeter was tested, and the name of the person approving the aircraft for return to service after the test.

39
Q

To what avionic equipment is the output from an encoding altimeter connected?

A

The ATC transponder.

40
Q

What is the allowable difference between the surveyed elevation of the airport and the indication of the altimeter when it is set to the local altimeter setting?

A

75 feet.

41
Q

What instruments in an aircraft are connected to the static system?

A

The airspeed indicator, vertical speed indicator, and altimeter.

42
Q

What are the differences between absolute, gauge, and differential pressure instrument systems?

A

An absolute pressure instrument, such as an altimeter, measures actual pressure. Gauge pressure instruments measure the difference between exiting barometric pressure and pressure inside a sealed container such as a Bourdon tube or a bellows. Differential pressure instruments display the difference between two pressures, such as pitot pressure and static pressure used to display airspeed.

43
Q

What are the basic methods of measuring fuel quantity in an aircraft?

A

Direct readying systems (sight gauges), floats that actuate a variable resistor, and capacitance-type systems.

44
Q

What do green, yellow, and red arc markings on an instrument mean?

A

Green indicates normal operating range, yellow indicates caution operating range, and red indicates prohibited operating range.

45
Q

Where are instructions found for adjustments to aa system that is displayed on an electronic display?

A

In the aircraft maintenance manual.

46
Q

Why is ground and bonding important for aircraft electrical systems?

A

Inadequate bonding or grounding can lead to unreliable operation of systems, EMI, electrostatic discharge damage to sensitive electronics, personnel shock hazard, or damage from lightning strike.

47
Q

What is meant by built-in test equipment (BITE)?

A

It is standard for monitoring systems to monitor themselves as well as the aircraft systems.

48
Q

What information is allowed to be depicted on electronic displays?

A

All information relating to flight and aircraft systems can be displayed on electronic displays. The main flight instruments are displayed on what is referred to as the primary flight display (PFD) or electronic flight instrument system (EFIS). Data displays for engine parameters, hydraulics, fuel, and other airframe systems are displayed on secondary flight displays or independent displays. These secondary displays are often referred to as multifunction displays (MFDs).

49
Q

What is the purpose of an engine-indicating and crew alerting system (EICAS)?

A

The system monitors aircraft systems for the pilot and displays engine and airframe parameters.

50
Q

What is a head-up display (HUD)?

A

A HUD proved critical flight information to the pilot on a see-through display that is in the pilot’s line of sight.

51
Q

Do the tests described in 14 CFR Part 43, Appendix E, apply to the altimeters installed in all certificated aircraft?

A

No, only those operated under instrument flight rules in controlled airspace.

52
Q

Who is authorized to conduct a static system test specified in 14 CFR 91.411?

A

A certificated Aviation mechanic holding an Airframe rating.

53
Q

When should a static system leak check be performed?

A

Any time the static system has been opened.

54
Q

What should be done to the static port that is not being used to conduct the leak test?

A

It should be taped over in such a way that the tape can not be overlooked or forgotten when the test is completed.

55
Q

Can an aviation mechanic with an A&P rating repair an instrument with a cracked glass?

A

No. The instrument must be replaced.

56
Q

How much leakages is allowed in the static system of an unpressurized aircraft?

A

With a pressure differential or 1 inch of mercury, the system must not show a loss of indicated altitude of more than 100 feet in one minute.

57
Q

How much leakage is allowed in the static system of a pressurized aircraft?

A

With a pressure differential equal to the maximum cabin differential pressure for which the aircraft is certificated, the system must not show a loss of indicated altitude of more than 2 percent of the equivalent altitude of the maximum cabin differential pressure or 100 feet, whichever is the greater, in one minute.

58
Q

What indication on the altimeter shows the pressure inside the static system has been decreased by 1 inch of mercury?

A

The altimeter will show an increase of approximately 1,000 feet.

59
Q

What are six tests that must be made when testing an altimeter?

A

Scale error
Hystersis,
After-effect
Friction
Case leak
Barometric scale error

60
Q

What does an angle of attack (AOA) indicator provide for the pilot?

A

The AOA offers a visual indication of the amount of lift the wing is producing at a given airspeed or angle of bank. The AOA delivers critical information to indicate the actual safety margin above an aerodynamic stall.

61
Q

What is the purpose of a stick shaker used on some aircraft?

A

It provides an artificial stall warning to the pilot.

62
Q

Why is it important for a stall warning system to be adjusted correctly?

A

A stall warning system is adjusted to allow sufficient margin and warning prior to an actual stall.

63
Q

What system does a takeoff warning system monitor?

A

The takeoff warning system senses when the power lever is advanced and checks for proper position of flaps and trim systems. A warning horn and caution light will be activated if the takeoff configuration is incorrect.

64
Q

What conditions are indicated by a landing gear warning system?

A

A red light will illuminate if any of the gear is unsafe condition. A green light shows when all landing gear are down and locked. An aural warning will sound a horn if the landing gear are not down when the throttles are retarded for landing.

65
Q

What is the purpose of bonding straps between flight controls and the attaching structure?

A

It provides a low-impedance ground return which minimizes interference from static electricity charges.

66
Q

Why are instrument panels shock-mounted?

A

To absorb low-frequency, high-amplitude shocks.

67
Q

What risks are associated with using compressed air for cleaning off an instrument panel or the exterior of the aircraft?

A

Pressurized air can quickly damage aircraft instruments if allowed to enter pitot/static ports or gyro vacuum lines.

68
Q

What cautions should be used when washing the exterior of an aircraft?

A

Never spray water into pitot/static ports. Water can cause damage or cause the instrument to read incorrectly.

69
Q

What dangers and challenges arise from reported intermittent warnings or caution annunciator lights?

A

An intermittent problem can be difficult to troubleshoot since the system may appear to be working correctly when looking for the problem. However, there was a cause for the intermittent warning or caution and the underlying problem must be understood.

70
Q

What precautions should be used when working on electrostatic-sensitive equipment?

A

Always used a body grounding strap (wrist strap) that connects the mechanic and the aircraft grounding structure. Work benches should be grounded, and components should be stored in anti-static bags.

71
Q

What precautions are to be sued when handling instruments that contain mechanical gyros?

A

Do not allow the instruments to be bumped, jarred, or dropped, as damage may occur.

72
Q

What cautions should be taken when performing a pitot/static system test?

A

Use the correct test equipment and procedures. Over-pressurizing the system can cuase damage. Upon completion of the leak test, be sure that the system is returned to the normal flight configuration. If it is necessary to block off various portions of a system, check to be sure that all blanking plugs, adaptors, or pieces of adhesive tape have been removed.