30 Questions
What is the primary function of a direct reading compass on a light aircraft?
To act as the primary heading reference
What type of metal is used in the magnet system of a direct reading compass?
Cobalt-steel
What is the purpose of the iridium-tipped pivot in the suspension of a direct reading compass?
To reduce pivot friction to a minimum
What is the material used for the case of a direct reading compass?
Non-magnetic metal or plastic
What is the function of the azimuth card or dial in a direct reading compass?
To indicate direction
What are the two common types of direct reading compasses in regular use?
Vertical panel mounted and suspended type
What is the primary reason for filling compasses with a liquid?
To make them aperiodic
What is the purpose of the damping devices in a compass?
To make the magnet system follow the magnetic meridians in the minimum of time without oscillating
Why is it important to check the calibration of a new compass from overseas before using it on an Australian aircraft?
To ensure the compass is calibrated for operation in southern latitudes
What is the effect of the liquid in a compass on the movement of the magnet system and its spider?
It sets up small eddies which are quickly dissipated
What is the purpose of the counterbalance weight in a compass?
To amplify the dip angle
What type of liquids are normally used in compasses?
Mineral or alcohol
What is the primary purpose of compass compensation in an aircraft?
To minimize the deviation error by aligning the aircraft on known headings
What is the effect of local magnetic fields in the aircraft on the magnetic compass?
It causes the compass to indicate a incorrect direction
What is the purpose of the compass correction card in an aircraft?
To correct for deviation errors during flight
What is the term for the error in the indication of an installed magnetic compass caused by local magnetic fields?
Deviation
What is the effect of magnetisable components in an aircraft on the Earth's magnetic field?
They distort the magnetic field
What is the result of adjusting the compensating magnets during compass calibration?
Decreased deviation error
What is the purpose of the compensator in a direct-reading compass?
To minimise the effects of local magnetic disturbances
How are the magnetic fields required for correction produced in the compensator?
By rotating a small bevel pinion
What is the direction of the magnetic field produced by the compensator dependent on?
The direction of the rotation of the pinion
What is the error that the laterally orientated magnets are adjusted for during compass compensation?
Error on north/south headings
What is the purpose of the bevel gears in the compensator?
To mesh with the bevel pinion
What is the error that the longitudinally orientated magnets are adjusted for during compass compensation?
Error on east/west headings
What is the principle behind the output of a flux valve?
AC synchronisation
Where are flux valves typically positioned in an aircraft?
In the wingtips or at the top of the tailfin
What is the purpose of using non-magnetic materials for flux valve location and mounting?
To minimize the effects of local magnetism
Why do some aircraft have two flux valves installed?
To provide redundancy and ensure continuous operation
What type of gyro is commonly used in remote compass systems to provide short-term stability of magnetic heading presentation?
Electrically driven directional gyro
What information is provided by the remote compass system to the pilot's displays?
Magnetic heading and navigation data
Test your knowledge on the different types of direct reading compasses used in turbine aeroplanes, including their construction and application. Learn about the vertical panel mounted compass and the suspended compass type, and how they are used in aviation.
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