11.5.1 - Instruments Flashcards Preview

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Flashcards in 11.5.1 - Instruments Deck (44)
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1
Q

What instruments need pitot and static pressure and which need static pressure only?

A

Altimeter - static pressure only

Vertical Speed Indicator (VSI) - Static pressure only

Airspeed Indicator - Pitot and Static pressure

Mach Indicator - Pitot and Static pressure

2
Q

Where are pitot probes and static ports located?

A

Pitot probes are located outside the aircraft pointing directly into the relative airflow. (RAM air pressure to measure airspeed indicator)

Static ports are located on either side of the fuselage or vertical fin or even small holes in the pitot-static head.

(Still or static air to measure VSI, altimeter & airspeed indicator)

3
Q

What type of device measures pressure on an Air-Data computer?

A

Air Data Module convert pitot or static pressure into digital output signals.

4
Q

What metal is used on a T.A.T?

(T.A.T = Total Air Temperature probe)

A

The temperature dependant resistor (thermistor) is made of platinum

5
Q

What pressure source does an altimeter use?

A

Static port pressure source

6
Q

Explain QNH

A

QNH is when an altimeter is set to measure altitude above the existing mean sea level pressure level of that region.

(Also known as indicated altitude)

7
Q

Explain QFE

A

QFE shows the local baro-pressure of the airfield.

An aircraft on the ground at this airfield will have an altimeter reading of 0.

8
Q

Explain QNE

A

STD (Standard) or QNE is an altimeter set to measure altitude above a standard reference in order to maintain clearance.

Standard reference = 1013.25 HPa or 29.92 inches of mercury

9
Q

Explain Altitude, height & elevation

A

Altitude is the vertical distance between sea level and the aircraft. Barometer set to QNH

Height is the vertical distance between aircraft and the terrain. Barometer is set to QFE

Elevation is the vertical distance from sea level to the airport or terrain.

10
Q

Explain the major difference between an altimeter and a Vertical Speed Indicator.

A

The Vertical Speed Indicator has as it’s operating mechanism a bellows, or pressure capsule, similar to that of an altimeter

Except that rather being evacuated and sealed, it is vented to the inside of the instrument case through a diffuser which is an accurately calibrated leak.

11
Q

What parameter does a Vertical Speed Indicator use?

A

Static Port Pressure

12
Q

What parameters does an Air Speed Indicator use?

A

An airspeed indicator is a differential pressure gauge that measures the difference between the pitot and the static pressure.

13
Q

What are I.A.S, T.A.S and G.S?

A

I.A.S = Indicated AirSpeed and is the uncorrected reading of an airspeed indicator

T.A.S = True AirSpeed and is the Calibrated Airspeed (CAS) with a correction applied to temperature and altitude

G.S = Ground Speed represents the actual speed of the aircraft over the ground. It is true airspeed adjusted for wind. A headwind decreases groundspeed while a tailwind increases it.

14
Q

Explain TAT and SAT.

A

TAT = Total Air Temperature and is the temperature of the compressed air against the flying aircraft. Higher speeds will cause TAT to be higher. Used for power setting of engine.

SAT = Static Air Temperature and is the temperature of the undisturbed air around the aircraft. The Air Data computer reads the TAT and uses MACH number to equate SAT.

15
Q

As altitude increases and I.A.S stays the same, what is happening to T.A.S?

A

T.A.S (True Airspeed) increases

i.e at 10,000 ft I.A.S = 400 kts, T.A.S = 450 kts

16
Q

What is the purpose of a barber pole?

A

Aircraft whose maximum speed is limited by structural
considerations have their never-exceed speed marked by a fixed red line on the dial of the airspeed indicator.

But if the maximum speed is limited by
the critical Mach number, the fixed red line is replaced by a red pointer (Barber pole) that is driven as a function of altitude.

17
Q

What parameters are needed to calculate Mach?

A

Mach number = Speed of aircraft / Speed of sound

Speed of sound is dependant on temperature which changes with altitude. As altitude increases, temperature decreases and speed of sound also decreases

(Speed of sound is speed at which small pressure disturbances move through the air, easier when air it hot)

Mach meter is connected to the pitot probe and static port.

18
Q

List the inputs to an Air Data. Computer?

A

Discretes,

TAS = total temperature

Total and static pressure

Baro setting

Angle of Attack

19
Q

List the devices used to detect a stall

A

Electrically operated vane on leading edge of wing (stall indicator only)

Slotted probe sticking out side of fuselage (angle of attack indicator)

vane that senses angle between longitudinal axis and airflow (angle of attack indicator)

20
Q

What are the 2 characteristics of a gyroscope?

A
  1. Rigidity in space
  2. Precession
21
Q

What is a vertical gyro used to indicate?

A

Roll and pitch signals

-Artificial horizon

autopilot

flight director

Weather Radar Antenna Stabilisation

22
Q

What is the purpose of a Directional Gyroscope?

A

A directional gyroscope along with a magnet compass indicate heading.

23
Q

In large commercial transport category aircraft what is an auxiliary pitot/static system used for?

A

The auxillary pitot-static system is used for the autopilot, yaw dampers, overspeed warning system, flight recorder, two flight directors and the reference for cabin differential pressure.

24
Q

What instruments use air from the static probes?

A

The altimeter, airspeed indicator and vertical speed indicator

25
Q

What is the function of the Air Data Modules(ADM’s)?

A

The function of the ADM is to convert pitot or static pressure into digital output signals.

26
Q

What altimeter altitude setting is used by aircraft at their cruising height?

A

Pressure altitude or Flight level is used (STD or QNE). It is an altimeter altitude setting above a standard pressure level which may be above or below mean sea level, usually 29.92 inches of mercury or 1013.2 mB or HPa

27
Q

Explain the difference between altitude and height.

A

Altitude is the vertical distance between an aircraft and sea level (QNH)

Height is the vertical distance between an aircraft and the terrain (QFE)

28
Q

What does a pilot use a Vertical Speed Indicator(VSI) for?

A

The VSI is used to help the pilot establish a rate of ascent or descent in order to reach a specified altitude at a given time. It is a measure of how fast or slow the aircraft is climbing or descending.

29
Q

What changes happen to true airspeed with increasing altitude?

A

Under non-standard sea level atmospheric conditions, A correction for the temperature and altitude is applied to the calibrated airspeed (CAS) which is normally done by a computer.

30
Q

What is the ‘Barber pole’ in an airspeed warning indicator?

A

If an aircraft’s maximum speed is limited by it’s critical Mach number, as Mach number varies with increasing altitude, a red pointer or ‘Barber pole’ is driven as a function of altitude and indicates the maximum speed.

31
Q

What are the inputs to a Central Air Data Computer and what does it output to?

A

The Central Air Data Computer (CADC) inputs include pitot and static pressures, baro setting, angle of attack and total air temperature.

The outputs of the CADC include autopilot, instruments, displays and navigation systems.

32
Q

Name a problem encountered by laser gyros and how is it prevented?

A

Laser lock-in which is where the two light beams get coupled together at low rotation rates.

This is prevented by a dither motor which helps prevent the loss of information at these low rates by vibrating the gyro assembly.

33
Q

What does an Inertial Navigation System(INS) measure and what information does it need to work?

A

The Inertial Navigation System (INS) measures the reaction forces of the various accelerations.

The information it needs to work are the initial starting location of the aircraft in terms of latitude and longitude which are inputted into the computer.

34
Q

Name the three parameters, with those the flight environment data system computes the altitude, velocity and temperatures:

A

The flight environment data system obtains data through the pitot static system:

  1. Static pressure
  2. Total (Pitot) pressure
  3. Total (RAM) air temperature
35
Q

Name all air data probes around the aircraft: (4)

A
  1. Pitot tube
  2. Static Probe (port)
  3. Combined pitot-static probe
  4. Total Air temperature prob
36
Q

Name all air data readings which are possible in the cockpit: (6)

A
  1. Altimeter (altitude)
  2. Vertical Speed Indicator (VSI)
  3. Airspeed indicator
  4. Machmeter
  5. Ram Air temperature
  6. Angle of attack indicator
37
Q

A pneumatic altimeter contains:

A

They have an electronic device in them that sends a digital code to the radar beacon transponder.

38
Q

The barosetting is QNH. After landing the altimeter shows the:

A

The elevation

(altitude of airport above mean sea level)

39
Q

During cruise flight the altimeter setting is:

A

QNE or STD (Flight level)

Which is the vertical distance between the aircraft and some set reference point that may be below or above mean sea level (29,92 inches of mercury or 1013.25 HPa)

40
Q

The pneumatic vertical speed indicator needs the ______ pressure.

A

Static pressure

41
Q

What turns the dial of a Radio Magnetic Indicator(RMI)?

A

A slaving torque motor causes a Directional Gyro to precess driving the rotor of an Autosyn transmitter which is electrically connected to an Autosyn motor that turns the dial of an RMI

42
Q

Explain the difference between True airspeed(TAS) and Calibrated airspeed(CAS).

A

Calibrated airspeed (CAS) is Indicated Airspeed (IAS) adjusted for instrument error. For example, the static port may not be entirely free from airflow distortion and a known correction must be applied to this instrument to compensate for the error.

True Airspeed (TAS) is calibrated airspeed adjusted for non-standard atmosphere conditions such as temperature and pressure.

True Airspeed (TAS) is equal to Calibrated Airspeed (CAS) at standard atmospheric conditions (sea level)

43
Q

What changes happen to true airspeed with increasing altitude?

A

It increases

44
Q
A