Instruments 2 Flashcards

1
Q

To what component in a hydraulic pressure indicating system would a pressure transmitter be connected?

A

The accumulator

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2
Q

Where in a hydraulic pressure indicating system would a pressure switch be located?

A

Downstream of the hydraulic pump

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3
Q

What is the purpose of a hydraulic pressure indicating system?

A
  • To ensure each system is working properly
  • To warn of any problems
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4
Q

What is the purpose of a hydraulic system low pressure warning light?

A

To give an indication if unsafe hydraulic pressure

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5
Q

What pressure detection/sensing devices may be used in a hydraulic pressure indicating system?

A
  • Bourdon tubes
  • Diaphragms
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6
Q

What component, within a hydraulic pressure transmitter, connects the detection device to the synchro transmitter rotor?

A

A sector gear

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7
Q

List aircraft systems that may utilised hydraulic power for their operation?

A
  • Landing gear
  • Brakes
  • Flught controls
  • Ground steering
  • Flaps
  • Doors
  • Canopies
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8
Q

What are the key components of a hydraulic system?

A
  • Reservoir
  • Accumulator
  • Hydraulic pump
  • Pressure relief valve
  • Low pressure sensor
  • Hydraulic system temperature sensor / bulb
  • Hydraulic system pressure sensor / transmitter
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9
Q

What unit of measure is normally displayed on the dial of a hydraulic pressure indicator?

A

Pounds per square inch (PSI)

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10
Q

What type of pressure detector / sensor is typically employed in a low pressure warning system?

A

A diaphragm

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11
Q

What colour is used for a low pressure warning light?

A

Amber

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12
Q

What components make up a hydraulic temperature indication system?

A
  • Temperature sensor
  • Indicator
  • Interconnecting wiring
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13
Q

In reference to a hydraulic system temperature indicating system - where is the temperature sensor normally fitted?

A

Just prior to the oil returning to the reservoir

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14
Q

Why is it important to monitor the temperature of hydraulic oil?

A

Above certain temperatures, the viscosity of the hydraulic oil changes - this then downgrades the performance of it

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15
Q

Type of temperature sensor used in a hydraulic oil temperature indicating system?

A

A bulb sensor

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16
Q

What type of quantity indication do the below use:

  • Hydraulic oil reservoir
  • Engine oil
A

Sight gauge

DC synchro system

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17
Q

The wiper arm in an engine oil quantity transmitter is connected to what component in the oil tank?

A

A float and actuator

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18
Q

3 types of fuel flow indicating systems?

A
  • Rotating vane
  • Impeller
  • Fuel mass flow
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19
Q

What output is provided by a fuel flow transmitter?

A

Electrical output signal proportional to the flow rate

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20
Q

What type of fuel flow indicating system is used to counter the problem of fuel density varition?

A

A mass fuel flow indicating system

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21
Q

In a rotating vane type fuel flow transmitter, what opposes the movement of the metering vane?

A

A calibrated spring

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22
Q

In a rotating vane type fuel flow transmitter, what component (driven by the metering vane) provides a DC voltage proportional to the fuel flow?

A

A wiper across the potentiometer

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23
Q

In a rotating vane type fuel flow transmitter - what provides a path for the fuel low in case the vane becomes jammed closed?

A

Bypass valve

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23
Q

In an impeller type fuel flow system - what component converts the transmitters pulsing signal into one that is used to drive the indicator pointer?

A

The amplifier / signal conditioner

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24
Q

What ‘relationship’ is used by a mass flow fuel indicating system?

A

Fuel mass and viscosity

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25
Q

What components make up an integrated fuel flowmeter system transmitter?

A
  • Housing
  • Motor driven impeller assembly
  • Flow metering chamber
  • Externally mounted magnetic pick-off assembly
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26
Q

How are the outer drum and impeller assembly in an integrated fuel flowmeter transmitter coupled to each other?

A

By calibrated spring

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27
Q

What are the 2 components in the integrated fuel flowmeter transmitter, are the magnets fitted to?

A
  • Outer drum
  • Impeller
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28
Q

Under which condition are the integrated fuel flowmeter transmitter magnets in alignment?

A

Under zero fuel flow conditions

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29
Q

3 functions performed by the integrated fuel flowmeter system computer?

A
  • Proved power for various cct of the system
  • Detects the number of pulses produced by the transmitter
  • Computes and integrates the fuel flow rate and fuel consumed for the display indicator
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30
Q

What 2 pieces of information are displayed on an integrated fuel flowmeter indicator?

A
  • Fuel flow
  • Fuel used / remaining
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31
Q

What does the computer in a fuel remaining / fuel used indicating system calculate?

A

Fuel consumed over a period of time from the flow rate during the period

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32
Q

What is provided on a fuel remaining / fuel used indicator to reset the counters to zero?

A

Mechanical reset button

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33
Q

What component within an integrated fuel flowmeter indicator provides feedback to the computer if the pointer position does not represent the fuel flow from the transmitter?

A

Timebase section

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34
Q

What type of transmitter is used in a volumetric fuel quantity indicating system?

A

Float arm type transmitter

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35
Q

What type of transmitter is used in a mass type fuel quantity indicating system?

A

Capacitance fuel probes

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36
Q

What 3 types of meter movements may be used in a volumetric fuel quantity indicating system?

A
  • Milliammeter
  • Ratiometer
  • Desynn and autosynn
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37
Q

What type of cct is used to indicate fuel contents in a capacitance fuel quantity indicating system?

A

A balanced bridge cct

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38
Q

What elec supply is required to power a mass type fuel quantity indicating system?

A

AC power

39
Q

What does a mass type fuel quantity indicating system take into account to indicate the weight of the fuel?

A

Fuel density (due to temp and pressure changes)

40
Q

Purpose of the fuel quantity indicating system?

A

Indicate the amount of fuel remaining int he fuel tank

41
Q

What is fuel quantity information used to determine?

A

Remaining aircraft flight time

42
Q

In what type of fuel tank does a float arm system work best?

A

Fuel tanks that are regular in shape

43
Q

In a volumetric fuel quantity indicating system - what happens as the float are rises or falls?

A

The arm rotates the wiper across the resistance winding, proportionally changing the resistance to correspond to the quantity of fuel remaining in the fuel tank

44
Q

2 advantages of the volumetric fuel quantity indication system?

A
  • Inexpensive to manufacture
  • Simple to maintain
45
Q

3 disadvantages of a volumetric fuel quantity indication system?

A
  • Foaming of fuel at high altitude cases the float are to ride too high
  • Mechanical damages can occur
  • Errors are introduced when the volume of the fuel changes doe to temperature variation
46
Q

4 advantages of a mass fuel indication system?

A
  • Ability to totalise all of the tanks
  • No moving parts (except the indicator itself)
  • High degree of reliability
  • Internal self-test feature
47
Q

In a mass type indicating system - the capacitance of what 2 substances is measured?

A
  • Air
  • Fuel
48
Q

What is the approx dielectric constant of fuel?

A

2

49
Q

In a mass type indicating system - how is fuel quantity indication accuracy ensured when the fuel tank is tilted?

A

2 or more probes are used

50
Q

What type of cct is a capacitance fuel quantity indicating system?

A

Balanced bridge cct

51
Q

What type of elec power supply is required to operate a capacitance fuel quantity indicating system?

A

AC power

52
Q

What is the relationship between mass, volume and density of fuel regardless of temperature?

A

M = V x D

53
Q

What is installed at the bottom of the fuel tank and always immersed in fuel, to measure the density of the fuel?

A

Compensation probe

54
Q

What affects the dielectric constant of fuel?

A

Change in temp will cause a change in the fuel density

55
Q

Aircraft applications for bleed air?

(PNEUMATIC PRESSURE INDICATING SYSTEMS)

A
  • Cabin pressurisation and air con
  • Anti-icing systems
  • Hydraulic reservoir pressurisation
  • Galley functions
  • Engine starting
56
Q

What aircraft pneumatic (bleed air) system parameters require monitoring?

A
  • Pressure
  • Temp
  • Flow
57
Q

Purpose of cabin pressurisation system?

A
  • Maintain constant low altitude in the cabin area during flight
58
Q

In cabin pressurisation systems:

1) what component is used to select the desired cabin pressure and rate of pressure change within the cabin?

2) What component opens and closes to maintain the desired cabin pressure?

A

1) Pressure controller

2) Outflow valve

59
Q

Define the term thrust?

A

Force produced by the engines - to propel the aircraft through the air

60
Q

What type of pressure measurement is used in a thrust indicator?

A

Differential pressure

61
Q

What reference pressure is used by a thrust indicator for a propeller driven aircraft?

A

Pilot pressure

62
Q

If a propeller is generating thrust, which probe will feel the highest pressure?

A

Thrust probe

63
Q

What reference pressure is used by a thrust indicator for a jet engine?

A

Static pressure

64
Q

If a jet engine is generating trust, which port will feel the lowest pressure?

A

Static port

65
Q

2 types of torquemeteres?

A
  • Hydraulic
  • Torque shaft
66
Q

Where are hydraulic cylinders in a hydraulic torque indicating system?

A

Secured to gearbox casing

67
Q

2 types of engines that use torque indicating systems to indicate engine power?

A
  • Turbo prop
  • Turbo shaft
68
Q

What type of force is being measure for torque indication?

A

Twisting force applied to the shaft

69
Q

What may occur if the engines rated torque is exceeded?

A

It may exceed the designed limit of the airframe and unnecessarily strain the power plant / engine

70
Q

In a hydraulic torque indication system - the aerodynamic resistance produced by the propeller, transfers a portion of torque to which component?

A

The stationary ring gear

71
Q

What is the relationship between the oil pressure in a hydraulic torque indication system and the torque applied?

A

Oil pressure is proportional to the torque applied

72
Q

What is used in a hydraulic torque indication system to sense oil pressure?

A

Bourdon tube

73
Q

In a torque shaft indication system - what is measures to give an indication of torque?

A

The amount of deflection between a torque shaft and a reference shaft

74
Q

How is the reference shaft mounted in a torque shaft indication system?

A

So that it forms a sleeve around the torque shaft

75
Q

What is located on the end of both the torque and reference shafts?

A

Exciter wheels

76
Q

What is generated as the exciter wheels pass by their respective magnetic pick-up assmblies?

A

Elec pulses

77
Q

How does the phase detector generate an output that represents the torque being measured?

A

By calculating the difference between the 2 magnetic pick up assembly signals

78
Q

What component makes up an engine pressure ratio (EPR) indication system?

A
  • Inlet pressure sensor
  • Number of exhaust pressure sensors
  • Pressure ratio transmitter
  • An indicator
79
Q

What type of jet engines use engine ratio indication systems? (EPR)

A

Axial flow turbojet engines

80
Q

How does an EPR indication system express the thrust produced?

A

The ratio of the air pressure at the engine outlet to the air pressure at the engine inlet

81
Q

What does the resultant of the forces produced by an EPR transmitter set of bellows, move?

What does this movement represent?

A

The core of an LVDT

The ratio of 2 pressures
- Engine inlet
- Engine outlet

82
Q

What must be done to the LVDT output singal prior to being transmitted to the indicator?

A
  • Amplify
  • The LVDTs signals are small so it must be amplified
83
Q

How does the pick-up unit of an engine vibration indication system mounted on an engine?

A

At right angles to the engines spin axis

84
Q

Components of an engine vibration indicator?

A
  • Test switch
  • Warning light
  • Rectifier
  • Vibration warning light
  • Amplifier / filter
  • Moving coil micro-ammeter
85
Q

What is the purpose of an engine vibration indication system?

A

To monitor engine vibration

86
Q

Why are engine vibration levels monitored?

A

A change in vibration may indicate an impending or partial fail

87
Q

What does the pick up unit in an engine vibration indication system consist of?

A
  • A spring supported permanent magnet
  • A sensing coil
88
Q

What does the magnet in the pick up unit tend to do when the engine vibrated?

A

Inertia - the magnet tends to remain fixed in space

89
Q

What is induced by the movement of the sensing coil through the magnetic field from the magnet in the pick up unit?

A

A voltage proportional to the amount of vibration

90
Q

Impeller type system - Typical faults and rectification?

A

Faults:
- US amplifier / signal conditioner
- Transmitter fitted in reverse

Rectification:
- Replacement of faulty item (commonly the transmitter)

91
Q

Rotating vane system - Typical faults and rectification?

A

Faults:
- Indicator reading becomes static (if vane in jammed)

Rectification:
- Replacement of the faulty item

92
Q

Volumetric system - Typical faults and rectification?

A

Faults:
- Moving parts are susceptible to wear
- Open cct
- Mechanical problems

Rectification:
- Replace transmitter assembly
- Calibration required following replacement

93
Q

Thrust gauge - Typical faults and rectification?

A

Faults:
- Leaks in the plumbing
- Indicator failing

Rectification:
- Tighten plumbing connections
- Replace a length of the plumbing if required
- Replace the indicator if US

94
Q

Torque indicator - Typical faults and rectification?

A

Faults:
- No common faults / typically very reliable

Rectification if fault found:
- Replacement of US item

95
Q

Engine pressure ratio indicator (EPR) - Typical faults and rectification?

A

Faults:
- Transmitter failing / wearing over time
- Leaking plumbing

Rectification:
- Replacement of entire component
- Tighten the plumbing / replace a length of plumbing

96
Q

Maintenance procedures?

A
  • Must be carried out IAW authorised data / relevant aircraft maintenance PUBs
  • Failure to comply - DFDA
  • Tasks to be carried our by only authorised / qualified personnel

Ensure standards are maintained and equipment is managed as prescribed by the OEM (original equipment manufacture) and handled / packaged by engineering branch personnel / bodies responsible for the equipment