Instruments Flashcards
Total pressure source is
The pitot tube
The 3 basic pressure insturments are _____ and use what source
-Airspeed indicator
( pitot pressure and static)
-Altimeter
Vertical speed indicator
(static only)
Position Error
Caused by disruption in the airflow over the pressure system source
Indicated airspeed is a measure of
Dynamic pressure
To get TAS from IAS you correct with
Density error
Postion error
Compressibility error
As aircraft climb altimeter aneroid capsule will
Expand due to the static pressure outside is reducing
QNE is
Pressure altitude
Before flying IFR the altimeter should read
+30 and - 40 on the correct altitude when the aircraft is on the ground.
Inside the VSI
Static pressure flows into the capsule then is leaked into the case
If there is more pressure inside the capsule then out, the VSI will show a descent.
Using alternate static will cause altimeter
to be slightly high because the pressure inside the cabin is lower.
If the static source is blocked VSI will
A slight under read
Rigidity is a gyro desire to
Remain in a fixed alignment in space unless acted upon by an external force.
A rate gyro
Has freedom of movement in two planes
Movement in the third is used to measure precession.
An Earth gyro is free to move in
3 planes but is controlled by gravity to maintain it’s positon relative to Earth.
A pneumatic gyro
Uses a high speed jet of air to spin the gyro.
Advantages of electrically driven gyro
-Cleaner and less maintenance
-Spin at a higher and more precise RPM
-increased resistance to toppling
Gyro inside TI and TC
-Spins away from pilot
-In a right turn, the top of the gyro will tip left.
The co-ordination ball on a TI/TC is
Independent from any power source.
HI/DI uses what kind of gyro
Tied Gyro
HI/DI has it’s spin axis
Vertically |||||||
The gyro in the Altitude heading is mounted inside 2 gimbal rings
-Inner gimbal allows for pitching
-Outer gimbal allows for rolling
The pendulous unit
Keeps the gyro axis aligned with the true vertical
Acceleration error during takeoff will show
Climbing turn to the right
An electrically driven Altitude indicator
-Uses mercury switches
-Connected to torque motors to maintain true vertical
Limits for pneumatically driven AI are
-55 degrees pitch
-90 degrees roll
Limits for electrically driven AI
-85 degree pitch
-No limit in roll
Flux valve in a RMI
is fixed in azimuth but pendulously suspended in damping fluid to allow it to remain horizontal.
DGU stands for
Directional gyro unit
Slaving rate of DGU to the flux valve is aprox
1-2 degrees per minute
Aparanet wonder is
-prominent at poles
-aprox 11 degrees per hour at nz
15 degrees x sin lat/hour
-compensated using drift nut or latitude rider.
Gyro inside TC and TI has its axis
lateral
Signs that ASI pitot has been frozen
airspeed will fluctuate then drop to a very small value
pitot pressure leaks out the drain hole
Purpose of a pendulous unit on a Artificial horizon is
To keep the gyro spin axis aligned with the true vertical
what effect of decrease in temperature while aircraft is flying level at FL 190
TAS decrease
EAS increase
