Ace - Aircraft Instruments And Systems-Pressure Flight Instruments

Front 1

What are your actions for a blocked static vent for the VSI

Back 1

1-Ensure P/S heat is on
2-Use alt static vent
3-Use limited panel
4-Fly correct att & pwr settings.

Front 2

How is air temp measured

Back 2

either a Total head thermometer or a Rosemount probe. Shown as TAT.

Front 3

What are Air Data Computers-
ADC's

Back 3

An ADC is fed by Pitot & Static lines on modern a/c and calcs RAS, TAS, MN, ROC, ROD & passes the relevant info electronically to the servo driven flt instruments.

Front 4

What are the advantages of ADC's

Back 4

Data calculated can be fed to the following-
1-Auto Pilot
2-FDS
3-FMS
4-GPWS
5-NAV AIDS
6-INSTR Comparison systs

Front 5

What are Press Flt Instr's

Back 5

1-ASI/MM
2-ALT
3-VSI

Front 6

How do press flt instr's work

Back 6

They mearsure atm press by using the P/S syst which detects the Total press (Static+Dynamic) and Static Press.

Front 7

What gives a measure of dynamic press

Back 7

Diff b/ween Total & Static Press
Dynm P=Tot P-Static P

Front 8

How does the ASI work

Back 8

Measures dynamic Press as the diff b/ween the total pitot press at the capsule diaphragm and the static press measured in the case

Front 9

What are ASI indicator errors

Back 9

1-Instr error
2-Press error
3-Density error
4-Compressibility error
5-Manoeuvre error
6-Blocked Pitot Static Syst

Front 10

How does a MM work. Give MM ratio formula.

Back 10

Measures the airspeed with relation to the speed of sound. A combination of ASI and ALT.
MM Ratio is: =(P-S)/S

Front 11

MM errors are-

Back 11

1-Instr error due to inaccuracies in the MM construction.
2-Press error- also called Position or Configuration error
3-Blocked Pitot/Static syst

Front 12

Does the MM suffer density or Temp errors.

Back 12

No, because its built in Alt capsule design and ratio to the dynamic Press compensates for the density & Temp variations.

Front 13

What are the ASI/MM indications for blocked static probe

Back 13

1-the static in the ASI/MM instr remains const so at const altitude the ASI/MM reads correctly
2-During the descent the ASI/mm will overread due to trapped low static with an increase in pitot press
3-During climb the ASI/MM will underread due to the decrease in pitot press against trapped high static P

Front 14

What are the indications for blocked pitot line ie. total press inside the ASI/MM capsule is const.

Back 14

1-At const altitude the ASI/MM reading will not change with a change of airspeed.
2-During descent the ASI/MM will underread due to an increase in Static P against a const pitot P
3-During climb the ASI/MM will overread due to decrease in static P against pitot p

Front 15

What actions for blocked Pitot/Static syst

Back 15

1-Check P/S heat is On
2-Use Alt static or Air Data Computer
3-Use limited panel, stby ASI
4-Fly correct Attitude and Pwr

Front 16

Define QNH

Back 16

Local Alt setting that makes the altimeter indicate the A/C's alt above mean sea level and hence airfield elev

Front 17

Define Regional QNH

Back 17

The lowest forecast QNH in an Altimeter Setting Region (ASR)

Front 18

Define QNH with respect to QFE

Back 18

QNH is QFE reduced to sea level using ISA.

Front 19

Define QFE

Back 19

This zeros the altimeter on the airfield elev datum.

Front 20

Define QFF

Back 20

Similar to QFE but uses actual conditions not ISA to find Sea Level Press.

Front 21

Define QNE

Back 21

This a height and not an alt setting. Shown on altimeter with 1013mB set. Used at High aerodromes where QFE press is low.

Front 22

What are the altimeter instuments errors

Back 22

1-Instr error
2-Press error
3-Time lag error
4-Baro error
5-Temp/Density error
6-Blocked static error

Front 23

What is the Alt indication for blocked static

Back 23

The altm will show the altitude where the blockage occurred.

Front 24

What are the actions for blocked static line giving unreliable alt readings

Back 24

1-Ensure P/S heat on
2-Use Alt static
3-Use limited panel
4-Fly correct attitudes & pwr settings

Front 25

Given temp deviation from ISA of 36 deg C, will the press altimeter overread, underread or read correctly and why.

Back 25

it will Overread because the temp deviation is colder than ISA.

Front 26

What are servo asstd altimeters

Back 26

these increase thae accuracy of simple press alts because the design uses an electrically conducted E&I bar arrangement and not mechanical links.

Front 27

What are the advantages of the servo asstd alts

Back 27

Improves design feature b/ween the capsule & pointer and removes 1)Instr error and 2) Time lag error

Front 28

How does the VSI work

Back 28

This measures the rate of change of static pressure and displays this as a ROC and ROD. The capsule has new static while the case has static that is restricted or slowed by a metering unit thus creating a differential static b/ween capsule & case. This translates as a ROC or ROD shown on the instr face.

Front 29

What are the errors suffered by the VSI

Back 29

1-Instr Time lag error
2-Press error
3-Manoeuvre error

Front 30

What type of scale does the VSI have

Back 30

a Logarithmic scale that has a greater sensitivity at small ROC's or ROD's. Zero at 9 O'Clock position.

Front 31

What's an Instantaneous VSI

Back 31

This is a VSI designed to counter time lag error. The IVSI has 2 spring loaded dashpots in the static line before the capsule that causes an immediate diff pressure to be sensed due to their inertia.

Front 32

What are the advantages of the IVSI

Back 32

Immediate change in climb or descent is show.

Front 33

What are the disadvantages of the IVSI

Back 33

Dashpots that sense vertical acceleration also affected by accel in a turn. Hence an initial ROC is shown when high bank angles are applied.

Front 34

On the VSI what are the indications of a blocked static port

Back 34

VSI displays Zero all the time.