29 Questions
What is the primary function of pressurised air or vacuum air in air-driven gyro systems?
To spin the gyro rotor up to speed and reference the gyro to the Earth
What is a disadvantage of vacuum operation in gyroscopic instruments at high altitudes?
Decreased gyroscopic stability due to lower atmospheric pressure
What is a potential problem with air passing through bearings in gyro systems?
Contamination by corrosion and dirt particles
What was the primary limitation of the venturi system used in early aircraft to provide vacuum for gyros?
Suction was only achieved at high airspeeds
What did the size of the venturi system refer to?
The amount of vacuum produced in inches of mercury
Why are filters important in air-driven gyro systems?
To prevent contamination and dramatically shorten the gyro's serviceable life
What is the typical frequency of the AC electric supply used in gyros?
400-Hz
What is the purpose of the finger contact assemblies in AC electric gyros?
To provide a path for the three-phase supply to the gyro stator
What is the approximate speed of the rotor in an AC electric gyro?
20 000–23 000 rpm
What is the advantage of DC gyro systems over AC systems?
Rugged, light-weight instrument
What is used to indicate power supply failure in an AC electric gyro?
A solenoid-actuated flag
What is the purpose of the flux valve in a remote indicating compass system?
To maintain the alignment of the gyro to the Earth's magnetic field
What type of instrument is the Horizontal Situation Indicator (HSI) considered?
Integrated instrument
What is the primary indicator of the Horizontal Situation Indicator (HSI)?
Gyro stabilised magnetic compass card
What inputs can the Horizontal Situation Indicator (HSI) receive from?
Radio navigation systems, air data systems and heading reference systems
What does the pilot have control over in the Horizontal Situation Indicator (HSI)?
The data to be displayed on the instrument
What is the benefit of the flux valve in a remote indicating compass system?
It removes the need for the pilot to update the card heading
What happens to the precession force when the turning motion ends?
It is removed
What determines the direction of the pointer's movement in the turn-and-slip indicator?
The direction of turn
What controls the rotor speed in an air-driven turn-and-slip indicator?
A regulator in the supply line
What is the purpose of the restraining spring in the turn-and-slip indicator?
To allow the indicator to display turns to the left or right
What is the function of the centrifugal cut-outs in an electrically-powered turn-and-slip indicator?
To control the rotor speed
What happens to the gimbal when the rate of turn is increased?
It tilts further against spring pressure
When are the wings aligned to the turn indicator marks?
During a rate 1 turn
What is the purpose of the spring restraint in the rate gyroscope?
To prevent the gyroscope from moving excessively
How does the rate gyroscope indicate the direction of the bank?
By moving the aircraft symbol to indicate the direction of the bank
What is the purpose of the annotation 'no pitch information' on the indicator scale?
To avoid confusion in pitch control
How does the pilot control the turn to the required rate?
By aligning the aircraft symbol with the graduations on the outer scale
What is indicated by the ball-type indicating element remaining centred?
Coordination of the turn
Test your knowledge of air-driven gyro systems, including the importance of filters, pressurized air and vacuum systems, and how they affect the service life of gyro rotors. Learn about the gyro erection system and its role in referencing the gyro to the Earth.
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