11.5 Compasses Q's Flashcards
What term is used to describe the angle the magnetic lines of force make with respect to the earths surface at a given point?
Magnetic Dip or Inclination
What term is used to describe the angular difference between TRUE NORTH and MAGNETIC NORTH?
Magnetic Variation or Declination
What two methods are used to minimize magnetic fields produced by current flowing in the wire used ti illuminate the compass?
- Low power lighting/low voltage bulb
- Screened/twisted wire pair.
Which magnetism type causes errors in compass systems and is caused by RESIDENT PERMANENT MAGNETIC FIELDS present within the aircraft caused by IRON and STEEL parts of the structure?
Hard Magnetism
How many cycles of error are caused by HARD magnetism?
One Cycle (created by magnets in speakers, generators or dc motors)
Which two aircraft compass errors occur during aircraft maneuvering are caused by pendulous suspension of the compass card?
- Turning Error (N&S)
- Acceleration Error (E&W)
What error is illustrated here?
Turning error (N&S)
What error is illustrated here?
Acceleration Error (E&W)
Which compass type incorporates both the magnetic sensing element and display element in one component?
Direct Reading AKA Standby Compass
What type of compass system is illustrated here?
Remote Reading/ Slaved Remote Compass System
What 2 components are now fitted to remote reading compass systems?
- Magnetic heading indicator (flux valve)
- Directional gyro.
Is this Stabilized or Non Stabilized?
Stabilised
Which magnetism type causes errors in compass systems which is temporary in nature and is caused by metallic parts of the aircraft which are magnetically soft becoming magnetized due to induction by the earths magnetic field?
Soft Iron Magnetism
How many cycles of error are caused by Soft Iron Magnetism?
2 cycles.
What causes the number of cycle errors (2) in regards to soft iron magnetism errors.
- Fuselage
- Wings
What instrument is this?
Horizontal Indicator
What instrument is this?
Course Deviation Indicator
Which coefficients does practical compass compensation deal with?
A,B and C
Which term describes the magnet system of a compass which must follow the magnetic meridians in the minimum time without oscillating?
Aperiodic or Deadbeat
What 2 devices achieve Aperiodic or Deadbeat operation of a compass?
- Compass Fluid
- Spiders/Filaments or wires
What name is given to the lines which show equal points of variation on the map ?
Isogonic
What type of tools should be used whenever performing any maintenance on or around direct reading compasses or flux valves?
Non-Magnetic aka Non-Ferrous Tooling
What compensates for the expansion and contraction of compass fluid with changes in temperature?
Expansion unit.
Describe coefficient of A
INSTALLATION ERROR, corrected by rotating the compass or flux valve.
Describe Coefficient of B
FUSELAGE magnetism, affecting east-west headings.
Describe Coefficient of C
WINGSPAN magnetism affecting North-South headings.
What are the 3 methods for carrying out compass swings?
- Comparison Method
- Electronic Compass Calibration
- Datum or Landing/Land compass
Which of the 3 compass swing methods use a higher level system to calibrate a lower level system.
Comparison Method.
What name is given to the white line down the center of a direct reading/standby compass?
Lubber line.
What should be checked on a new compass from overseas before use in Australian aircraft?
Counterbalanced magnet system for Southern Hemisphere.
In regards to remote compass compensation what happens when the potentiometers are rotated with respect to calibrated dials?
Inject very small DC currents into the flux detector coils.
Name some compass swing precautions.
1 Swung in area free from all unusual magnetic influences.
2. Are not near any hangars or other buildings.
Check swings (different to a compass swing) are checked at which points?
North, south, east, west.
