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34 Cards in this Set

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  • Back
What are your actions for a blocked static vent for the VSI
1-Ensure P/S heat is on
2-Use alt static vent
3-Use limited panel
4-Fly correct att & pwr settings.
How is air temp measured
either a Total head thermometer or a Rosemount probe. Shown as TAT.
What are Air Data Computers-
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.
What are the advantages of ADC's
Data calculated can be fed to the following-
1-Auto Pilot
6-INSTR Comparison systs
What are Press Flt Instr's
How do press flt instr's work
They mearsure atm press by using the P/S syst which detects the Total press (Static+Dynamic) and Static Press.
What gives a measure of dynamic press
Diff b/ween Total & Static Press
Dynm P=Tot P-Static P
How does the ASI work
Measures dynamic Press as the diff b/ween the total pitot press at the capsule diaphragm and the static press measured in the case
What are ASI indicator errors
1-Instr error
2-Press error
3-Density error
4-Compressibility error
5-Manoeuvre error
6-Blocked Pitot Static Syst
How does a MM work. Give MM ratio formula.
Measures the airspeed with relation to the speed of sound. A combination of ASI and ALT.
MM Ratio is: =(P-S)/S
MM errors are-
1-Instr error due to inaccuracies in the MM construction.
2-Press error- also called Position or Configuration error
3-Blocked Pitot/Static syst
Does the MM suffer density or Temp errors.
No, because its built in Alt capsule design and ratio to the dynamic Press compensates for the density & Temp variations.
What are the ASI/MM indications for blocked static probe
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
What are the indications for blocked pitot line ie. total press inside the ASI/MM capsule is const.
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
What actions for blocked Pitot/Static syst
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
Define QNH
Local Alt setting that makes the altimeter indicate the A/C's alt above mean sea level and hence airfield elev
Define Regional QNH
The lowest forecast QNH in an Altimeter Setting Region (ASR)
Define QNH with respect to QFE
QNH is QFE reduced to sea level using ISA.
Define QFE
This zeros the altimeter on the airfield elev datum.
Define QFF
Similar to QFE but uses actual conditions not ISA to find Sea Level Press.
Define QNE
This a height and not an alt setting. Shown on altimeter with 1013mB set. Used at High aerodromes where QFE press is low.
What are the altimeter instuments errors
1-Instr error
2-Press error
3-Time lag error
4-Baro error
5-Temp/Density error
6-Blocked static error
What is the Alt indication for blocked static
The altm will show the altitude where the blockage occurred.
What are the actions for blocked static line giving unreliable alt readings
1-Ensure P/S heat on
2-Use Alt static
3-Use limited panel
4-Fly correct attitudes & pwr settings
Given temp deviation from ISA of 36 deg C, will the press altimeter overread, underread or read correctly and why.
it will Overread because the temp deviation is colder than ISA.
What are servo asstd altimeters
these increase thae accuracy of simple press alts because the design uses an electrically conducted E&I bar arrangement and not mechanical links.
What are the advantages of the servo asstd alts
Improves design feature b/ween the capsule & pointer and removes 1)Instr error and 2) Time lag error
How does the VSI work
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.
What are the errors suffered by the VSI
1-Instr Time lag error
2-Press error
3-Manoeuvre error
What type of scale does the VSI have
a Logarithmic scale that has a greater sensitivity at small ROC's or ROD's. Zero at 9 O'Clock position.
What's an Instantaneous VSI
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.
What are the advantages of the IVSI
Immediate change in climb or descent is show.
What are the disadvantages of the IVSI
Dashpots that sense vertical acceleration also affected by accel in a turn. Hence an initial ROC is shown when high bank angles are applied.
On the VSI what are the indications of a blocked static port
VSI displays Zero all the time.