AEIS CHAPTER 4 Flashcards
(ICAO) stands for
International Civil Aviation Organisation
The ICAO defines the sea-level ISA as:
Pressure = ?
Temperature = ?
Humidity = ?
Pressure = 0 psi, Temperature: 15deg.celcius, Humidity: 0%
Define lapse rate
rate of change in temperature with altitude
Standard pitot-static head or probe is mainly used on i)
light aircraft
what is the key disadvantage of a standard pitot-static head or probe and what is done to combat it?
pressure probe prone to be blocked by sand and insects. thus a special “trapped” form of pressure probe is used
why is the electrically-heated pitot static tube used?
prevent ice formation at high altitudes or cold climates
what will happen if an electrically-heated pitot static tube is not used in cold climates?
probe openings get blocked, causing false indications or complete failure to the indicators
why is it better to seperate the static vent and pitot head?
static pressure obtained from pressure heads is not always a true value of still air pressure
pitot tube is usually located at i) for aircrafts operating at speeds above sound
fuselage nose
For aircrafts operating below speed of sound (343m/s), pitot tube is usually located i), ii), iii)
ahead of wing tip, ahead of vertical stablizer, or at side of fuselage nose section
where are static vents located?
on the skin of fuselage, one on each side of the fuselage
why are the static vents interconnected?
to minimise dynamic pressure effects
sensitive altimeter works through the i) which will move the ii) that drive the iii)
i) expansion and contraction of the water capsule
ii) mechanical linkages that drive the
iii) altimeter needles accordingly
when does the water capsule in a sensitive altimeter expands?
when aircraft is ascending, and static pressure decreases
when does the water capsule in a sensitive altimeter contracts? and comment on the static pressure
when aircraft is descending, and static pressure increases
compare the sensitive altimeters to a servo-assisted altimeter
servo-assisted altimeter are more accurate through use of electronics and motors
(VSI) stands for
vertical speed indicators
what is the function of a VSI
used to indicate if the aircraft is ascending, descending or in level-flight
if the VSI indicates 0, what does it mean
it means that the aircraft is in level-flight
VSI operates from i) , it is a ii) instrument
static pressure, differential pressure
during descend, the capsule in the VSI i) to indicate a descend because static pressure ii)
expands, increases
during ascend, the capsule in the VSI i) to indicate a ascend because static pressure ii)
contracts, decreases
(ASI)
Airspeed indicator
(ASI) measures the i) to indicate the speed of the aircraft
difference between pitot and static pressure
when the aircraft is parked on the ground, the two pressures in the (ASI) is i)
equal
which type of aircraft are required by the FAA to have Airspeed Indicator Markings?
aircraft weighing 12500 pounds or less
What should be the ASI reading prior to takeoff
zero
what should be the ASI reading prior to takeoff when there is a strong wind blowing into the pitot tube?
higher than zero
what is used to measure the difference between pitot and static pressure in an ASI
a sensitive differential pressure gauge
during acceleration at level flight, ascend or descent, the capsule in an ASI i)
expands
during deceleration at level flight, ascend or descent, the capsule in an ASI i)
contracts
when the pitot tubes are blocked when the aircraft is ascending at constant speed, the reading on the ASI will i) - read
over-read
when the pitot tubes are blocked when the aircraft is descending at constant speed, the reading on the ASI will i) - read
under-read
when the static ports are blocked when the aircraft is ascending at constant speed, the reading on the ASI will i) - read
under-read
when the static ports are blocked when the aircraft is descending at constant speed, the reading on the ASI will i) - read
over-read
when the pitot tubes leak when aircraft is ascending or descending, the reading on the ASI will i) - read
under-read
when the static ports leak when aircraft is ascending or descending, the reading on the ASI will i) - read
over-read
IAS refers to
indicated airspeed
IAS =
airspeed indicator reading + instrument error correction
CAS refers to
calibrated airspeed
CAS =
IAS + pressure error correction
EAS refers to
equivalent airspeed
EAS =
CAS + compressibility error correction
TAS refers to
True Airspeed
TAS =
EAS + density error correction
mach number is the ratio between i) and ii)
true airspeed(TAS) and the local speed of sound
machmeter utilises the aircraft’s i) system to generate M
pitot-static system
high speed aircraft, including airlines and business jets, have i) mach numbers
critical
what happens if the critical mach numbers is exceeded?
it will create shock waves on the aerofoils resulting in buffet or mach tuck
what is mach tuck
aircraft nose pitching downwards
what is buffeting
where wings experience aerodynamic turbulence
when aircraft is at a higher altitude at the same TAS, the mach number will i) because speed of sound ii)
increase, decreases
machmeter makes use of a i) capsule and a ii) capsule
altimeter, airspeed
airspeed capsule in a machmeter accepts i) inputs
pitot-static
altitude capsule in a machmeter accepts i) inputs
static
when the pitot tubes are blocked and the aircraft is ascending at constant speed, the mach number will i)-read
over-read
when the pitot tubes are blocked and the aircraft is descending at constant speed, the mach number will i)-read
under-read
when the static ports are blocked and the aircraft is ascending at constant speed, the mach number will i)-read
under-read
when the static ports are blocked and the aircraft is descending at constant speed, the mach number will i)-read
over-read
pitot-static testers are used to i)
check for leaks
how do pitot-static testers check for leaks?
by simulating pitot and static pressures at different airspeeds and altitudes to the flight instruments
EFD refers to
electronic flight display
the high tech smart sensors for aircraft instrumentation are more i) and require less ii) compared to analogue counterparts
reliable, maintenance
