Flight Instruments Flashcards
Pitot static instruments
Static air pressure and dynamic pressure for airspeed indicator, altimeter, vertical speed indicator
Airspeed indicator
Air into Pitot tube into static chamber and pressure chamber, drain hole for moisture, tube to ASI, cancel out static pressure with static port or alternate static source, dynamic pressure remains for ASI, VSI and altimeter only use static pressure
Use of alternate static source
Inside flight deck, slightly lower pressure
Causes:
Altimeter showing higher altitude
ASI showing greater airspeed
VSI showing short climb before stabilizing
Altimeter function
Stack of sealed aneroid wafers at 29.92Hg pressure - connected to pointer
Higher static pressure pushes down - decrease in altitude
Lower static pressure let’s it expand - increase in altitude
Altitude standards
Sea level pressure at 29.92
Sea level air temp at 15/59
Adjustments for non-standard barometric knob
Altimeter impact by non standard pressure
From high to low look out below
Altimeter impact by non standard temp
From hot to cold look out below
Setting the altimeter
Adjust pressure scale Via kollsmann window
ATC or tower for local pressure
Pressure vs altitude
1in of mercury = 1000ft
Types of altitude
Indicated
True - above MSL
Absolute - above ground level AGL
Pressure - set to 29.92, used to compute density altitude, true altitude, true airspeed
Density - changes due to temp, if below standard temp then density altitude is below pressure altitude
Vertical speed indicator
Diaphragm and case receive static pressure, case via calibrated leak
Climb: pressure in Diaphragm changes immediately, while case pressure remains higher due to metered leak until calibrated
Types of airspeed
Indicated
Calibrated - corrected for errors
True TAS - CAS corrected for temp and altitude, TAS increases with altitude, add 2% of CAS for each 1000ft
Groundspeed - actual speed over ground
Airspeed indicator markings
White arc - flap speed range, lower limit stall speed, upper limit max flaps
Green arc - lower end clean config stall speed, upper limit max structural cruise speed
Yellow arc
Red line
Other airspeeds
Design maneuvering speed V A Landing gear operating speed V LO Landing gear extended speed V LE Best angle of climb speed V X Best rate of climb speed V Y Single engine best rate of climb V YSE Minimum control speed V MC
ASI with blocked static system
ASI lower than actual above clog
ASI higher than actual below clog
