u10 Flashcards
must check pitot-static system how often for IFR flights
2 years
there is a dent in the fuselage that results in the static port being slightly tilted forwards towards the oncoming air, how does this affect the readings
static port reading higher static pressure
where is the alternate static source located in an unpressurized plane? pressurized?
unpressurized: inside cowling or cabin, rip static line, break VSI glass
pressurized: inside cowling
when you turn on the alternate static source, what will your instruments say
VSI = momentarily a climb but level out to zero
ALT = slightly higher (50ft)
ASI = reads slightly faster (since larger pressure difference)
IFR flights require what equipment as part of the pitot static system
pitot heat
alternate static source
how do the instruments read when there’s a completely blocked STATIC port
ASI extra slow in climb
ASI extra fast in descent
ALT = frozen at previous altitude
VSI = 0
how do the instruments read when there’s a completely blocked PITOT
ASI = increases during climb
ASI decreases during descent
ALT and VSI unaffected
how do the instruments read when there’s a PARTIALLY blocked PITOT
ASI = 0
* pitot drains until it pitot = static pressure
what is ASI position error
mounted far from slipstream + ahead of wing so that it’s taking in undisturbed air
at high AoA, less straight flow into pitot tube = less accurate readings
what is ASI instrument error
friction from the pitot itself
what is ASI compressibility error
occurs at high speed (greater 250KT) and high altitudes
what is ASI density error
changes in altitude and temperature will make you have a different TAS than IAS
how can you easily calculate your TAS when you know your pressure altitude and IAS
add 2% to your IAS for every 1000 ft pressure altitude
indicated airspeed:
what is it
does indicated stall speed change with altitude or temperature
read off dial
always same indicated stall speed because it’s based on critical AoA
what is calibrated airspeed
indicated airspeed correcting for position and instrument errors
True airspeed
- corrects for what errors
- does true stall speed change with altitude or temperature
CAS corrected for density errror (high temp or altitude)
true stall speed increases with altitude -> less air molecules at high altitude/temp so need to fly faster to get enough lift to stay flying
why does bank angle increase the stall speed
need to fly faster to get the same amount of vertical lift
why do heavy planes have faster stall speeds
because they fly at higher AoA, so they’ll reach their critical AoA at faster speeds
add _____ the gust factor to your approach speed on turbulent days. so if my normal approach is 65 KT, on a 20G30 day, i should approach at
half
10KT difference = 10/2 =5
65+5=70
approach at 70KT
how does contamination on the wing increase stall speed
smooth airflow separates from the wing earlier so it can’t generate as much lift
explain how at higher power settings, you have a lower stall speed
upward component of thrust changes the relative airflow, so now you’re at a lower AoA = farther from critical at same speed
plus the propeller sends more airflow over the top of the wing = more lift
why do you have higher takeoff and landing rolls on hot, high altitude days?
can i compensate and slow my approach down so that i approach at a lower TAS?
on hot days or high altitude, there’s lower air density = less drag = flying at faster TAS than your indicated says you are
no don’t you dare because even though your TAS is slower (shorter landing roll), your IAS is really close to stall speed
what is Vmc
what happens if you fly below Vmc in a critical engine failure? above?
minimum speed to control and maintain level flight in (critical) engine failure
at speeds below Vmc, the plane will yaw and roll towards the failed engine
at speeds above Vmc, there’s enough air to hit the rudder so that we can control adverse yaw
which engine is the critical engine in a multi-engine plane? why?
left is critical engine
because the right blade (down) generates more thrust, so if the left engine quits, the right engine causes LOTS more adverse yaw. and when it yaws left, there’s more airflow over right wing so it starts to roll left further
POH Vmc is different than actual irl Vmc.
what is the POH Vmc and how does that change if you have a heavy plane with a forward CoG
POH Vmc based on:
- lightest plane
- most aft CoG
heavy plane = lower Vmc because slow speeds give us more controllability
forward CoG = lower Vmc because longer arm means that we need less rudder to control adverse yaw
what is V1
decision speed
if the engine fails before this speed, you can abort takeoff
if the engine fails above this speed, you’re committed to climb because you can’t stop on remaining runway
what is V2
speed that the plane can be safely flown on one engine (turbine only - use Vyse for piston)
what is Vsse
Vmc + 10KT buffer
what is Vyse
most altitude gain in shortest time for a single engine (when multi failure)
what is Vxse
most altitude gain in shortest distance on a single engine (multi failure)
how does the VSI work
how long is the lag time
diaphragm pressure (static port) compared to instrument cavity pressure
small hole so that static air can leak into the instrument cavity at a calibrated rate
6-8 sec lag
what is VSI reversal error
sharp and sudden pitch changes cause the VSI to temporarily show the opposite of what the plane is doing because of the sudden pressure change around the plane
how does the ALT work
measure outside air pressure to pre-set diaphragm
what causes altimeter errors
low pressure systems and abnormally high pressure systems
temperature variations
mountain waves
an altimeter that’s set too high will read _______
too high
an altimeter set too low will read _____
too low
in the northern hemisphere, you’re starting to drift to the right of your track. this means i’m flying into an area of
LOW PRESSURE
**your plane is descending while you maintain an indicated altitude as you fly closer to the low so reset your ALT
air pressure of cold air changes at a __________ vertical depth than warm air due to
greater
closer pressure levels
i’m flying through a valley, how does my ALT get affected
valley = fast air = lower pressure = ALT says i’m higher than i actually am
how can mountain waves fuck up your ALT
strong airflow over mountain tops makes fast oscillating air
- fast = pressure drop = ALT reads too high
- ALT can’t register the decent in the downdrafts because of the decrease in pressure (and downdrafts so smooth that pilot doesn’t notice)
indicated altitude
pressure altitude
true altitude
absolute altitude
density altitude
indicated altitude - read off dial
pressure altitude - when ALT set to 29.92
true altitude - height above SL
absolute altitude - height AGL
density altitude - pressure altitude corrected for non-standard temperature
what is an encoding altimeter
using your mode C transponder, ATC can know your pressure altitude
the compass case is filled with ______ to dampen oscillations
white kerosene
when is a compass accurate in flight
level flight and no accelerations
- but in steady climb it’s fine
what is magnetic dip
where is it affected most
how is the compass mounted to compensate for dip
at poles, the compass card will dip cowards towards the ground = error reading
worst at poles and very high altitudes
balanced like a pendulum
what is magnetic variation
difference between true north and magnetic north
isogonic line vs agonic line
agonic line = 0º
isogonic line = line that joins places of equal variation
when going from TRUE to MAG heading, what’s the saying
east is least
west is best
what is magnetic deviation
compass error within plane due to magnetic disturbances of the electronic equipment
how often does a mechanic do a compass swing
where is the information recorded and what else must the mechanic publish
annually
journey log
compass correction card
what causes the northerly turning error
what’s the acronym
during a turn, friction and centrifugal force will cause inaccurate compass readings due to magnetic dip
Undershoot
North
Overshoot
South
what causes acceleration error on compass
what’s the acronym
magnetic dip shows errors when flying east/west headings and you accelerate -> shows turn to the north or south
Accelerate
North
Decelerate
South
the gyroscope operates on two principles
rigidity in space - once spinning, the gyro stays in same position and the panel rotates around it
precession - deflection 90º to the force you apply
how are the gyro instruments powered
AI and HI by engine driven vacuum pump
TC electrically
friction from worn out bearings on the gyroscope instruments can cause what
precession
the heading indicator is:
mounted ______ but spins _______
_____ causes the HI to precess
must reset HI every _____
why is the HI better than compass
must be reset after ____º pitch or bank due to tumbling
mounted vertically but spins horizontally
bearing friction
15 mins
- doesnt have compass errors (northerly turning or acceleration)
55º
the attitude indicator is
mounted _____ but spins ______
acceleration error
deceleration error
_______ can cause precession
must be reset after ____º pitch or bank because it would have tumbled
mounted horizontally but spins vertically
acceleration = shows climb
deceleration = shows descent
bearing friction
55º
turn coordinator indicates ______ and ______ of turn
rate and quality
why does the TC identify yaw and ROLL, whereas the turn and slip indicator shows yaw only
TC gyro mounted 30-35º so it’s able to show ROLL
the inclinometer shows turn _______
quality (yaw)
how can you correct a skid or slip
adjust bank or rudder
skid = _____ bank for rate of turn = ______ rudder
not enough bank = too much rudder q
skip = _______ bank for rate of turn = _____ rudder
too much bank = not enough rudder
a faster plane needs a _____ bank angle to complete a standard rate (3º/sec) turn compared to a slow plane
what’s the equation needed to find out what bank angle you need to do a standard rate turn at a given speed
greater
Bank angle = (KTAS /10) + 7
what is a gyromagnetic compass
why is it better than compass and HI
horizontal gyro linked to magnetic north via flux valve (detects mag north on it’s own)
better than compass = less oscillations and no turning errors
better than HI = self corrects to magnetic north so no precession
components of a gyromagnetic compass system
flux valve (magnetic north sensor)
gyroscope - to always point in same direction
compass repeaters - send mag north info to torque motors
torque motors - rotate the dial to point to your heading
turn/accelerator cut out switch - activates to prevent turn/acceleration errors
slaved GMC vs free GMC
(gyromagnetic compass)
slaved GMC = automatic readings to point to magnetic north
free GMC = gyro not linked to compass so you have to manually reset HI as you fly (use at poles because high compass dip so automatic calculations aren’t as perfectly reliable)
when recovering from an unusual attitude, which instruments should you use
TC and ASI
what are the control instruments
AI and tachometer
what are the performance instruments
ASI
ALT
VSI
HI
TC
