AVIT 415 BLOCK 1 EXAM QUESTIONS WITH
100% CORRECT ANSWERS
What instruments are part of the pitot-static system?
Airspeed
Altimeter
VSI
Total pressure = ___ + ___
Static + Dynamic
How does the airspeed indicator work?
Takes the difference Between Ram Air Pressure and Static Air Pressure
Airspeed Markings
Bottom of white: Vso
Top of white: Vfe
Bottom of green: Vs
Top of green: Vno
Bottom of yellow: Vno
Top of yellow: Vne
Red line: Vne
Types of airspeeds
ICET
Indicated: what the ASI is indicating
Calibrated: IAS corrected for installation and position errors
Equivalent: CAS corrected for compressibility
True: CAS corrected for non-standard temperature and pressure
How does the altimeter work?
The altimeter is connected to the static port. Inside are sealed aneroid wafers. As the barometric
pressure increases, the wafer compresses, decreasing alt. As the barometric pressure decreases,
the wafer expands, increasing alt.
Types of altitudes
Indicated: what the altimeter reads
Absolute: AGL
True: MSL
Pressure: the height above the standard datum plane (29.92 - current altimeter x 1000 + 845')
Density: pressure altitude corrected for non standard temperature
, Altimeter errors
High to low, look out below
Hot (less dense air) to cold (more dense air), look out below
How does the VSI work?
The VSI is a pressure differential instrument. Inside the case is an aneroid much like the one on
an airspeed indicator. Both the inside of this aneroid and the inside of the instrument case are
vented to the static system, but the case is vented through a calibrate leak that causes the pressure
inside the case to change more slowly than the pressure inside the aneroid. In a climb, we have
less static pressure and the diaphragm will contract. In a descent, we have more static pressure
and the diaphragm will expand.
What will the instruments read in a pitot blockage and what corrective action must we do?
ASI - read 0 (pitot tube) or freeze (pitot mast)
ALT - not affected
VSI - not affected
Corrective action: use pitot heat
What will the instruments read in a static blockage and what corrective action must we do?
ASI - will not be reliable
ALT - freeze
VSI - read 0
Corrective action: alternate static source
How do we configure the cabin to use the alternate static source?
- Close storm window
- Close cabin vents
- Turn heat and defrost on
Instrument cockpit check
ASI - should read 0 unless windy
ALT - within 75 ft of field elevation
VSI - should read 0, but if it is stable at 100' we can still go
Attitude - within 5 degrees within 5 min
Heading - known heading
Turn coordinator - check during a turn for correct direction of turn and ball deflection
Note: Begin this check once off the ramp
FAR 91.121 - altimeter settings
100% CORRECT ANSWERS
What instruments are part of the pitot-static system?
Airspeed
Altimeter
VSI
Total pressure = ___ + ___
Static + Dynamic
How does the airspeed indicator work?
Takes the difference Between Ram Air Pressure and Static Air Pressure
Airspeed Markings
Bottom of white: Vso
Top of white: Vfe
Bottom of green: Vs
Top of green: Vno
Bottom of yellow: Vno
Top of yellow: Vne
Red line: Vne
Types of airspeeds
ICET
Indicated: what the ASI is indicating
Calibrated: IAS corrected for installation and position errors
Equivalent: CAS corrected for compressibility
True: CAS corrected for non-standard temperature and pressure
How does the altimeter work?
The altimeter is connected to the static port. Inside are sealed aneroid wafers. As the barometric
pressure increases, the wafer compresses, decreasing alt. As the barometric pressure decreases,
the wafer expands, increasing alt.
Types of altitudes
Indicated: what the altimeter reads
Absolute: AGL
True: MSL
Pressure: the height above the standard datum plane (29.92 - current altimeter x 1000 + 845')
Density: pressure altitude corrected for non standard temperature
, Altimeter errors
High to low, look out below
Hot (less dense air) to cold (more dense air), look out below
How does the VSI work?
The VSI is a pressure differential instrument. Inside the case is an aneroid much like the one on
an airspeed indicator. Both the inside of this aneroid and the inside of the instrument case are
vented to the static system, but the case is vented through a calibrate leak that causes the pressure
inside the case to change more slowly than the pressure inside the aneroid. In a climb, we have
less static pressure and the diaphragm will contract. In a descent, we have more static pressure
and the diaphragm will expand.
What will the instruments read in a pitot blockage and what corrective action must we do?
ASI - read 0 (pitot tube) or freeze (pitot mast)
ALT - not affected
VSI - not affected
Corrective action: use pitot heat
What will the instruments read in a static blockage and what corrective action must we do?
ASI - will not be reliable
ALT - freeze
VSI - read 0
Corrective action: alternate static source
How do we configure the cabin to use the alternate static source?
- Close storm window
- Close cabin vents
- Turn heat and defrost on
Instrument cockpit check
ASI - should read 0 unless windy
ALT - within 75 ft of field elevation
VSI - should read 0, but if it is stable at 100' we can still go
Attitude - within 5 degrees within 5 min
Heading - known heading
Turn coordinator - check during a turn for correct direction of turn and ball deflection
Note: Begin this check once off the ramp
FAR 91.121 - altimeter settings
