PIPER AIRCRAFT, INC.
PA-28-161, WARRIOR III
MAINTENANCE MANUAL
PAGE 18
Nov 30/06
3H18
34-20-00
Trouble Cause Remedy
CHART 4
TROUBLESHOOTING MAGNETIC COMPASS
Excessive card error. Compass not properly Compensate instrument.
compensated. (See Magnetic Compass -
Adjustment, above.)
External magnetic interference. Find magnetic interference
and eliminate if possible.
Replace instrument.
Excessive card oscillation. Insufficient liquid. Replace instrument.
Card sluggish. Weak card magnet. Replace instrument.
Excessive pivot friction or Replace instrument.
broken jewel.
Liquid leakage. Loose bezel screws. Replace instrument.
Broken cover glass. Replace instrument.
Defective sealing gaskets. Replace instrument.
Discolored markings. Age. Replace instrument
Defective light. Burned out lamp or broken circuit. Check lamp or continuity
of wiring.
Card sticks. Altitude compensating diaphragm Replace instrument.
collapsed.
Card does not move when The gears that turn compensating Replace instrument.
compensating screws are turned. magnets are stripped.
Compass swings erratically Normal. None.
when radio transmitter is keyed.
C. Magnetic Compass
(1) Description and Operation
The magnetic compass is a self-contained instrument. The compass card is mounted on two
magnets, which tend to align themselves with the Earth’s magnetic field, permitting the
compass to use Earth’s magnetic north as a reference. Due to magnetic attractions created by
nearby metal surfaces and the airplanes’s electrical equipment, the compass magnets are
frequently “pulled” away from magnetic north. Much of this error (not all) can be removed by a
procedure called swinging the compass (see Adjustment of Magnetic Compass, below).
The compass should be swung whenever instruments or radios are changed and at least once
a year. For night operations, the instrument is internally lit. The light is powered by the
airplanes’s instrument lighting circuit.
(2) Troubleshooting
See Chart 4.
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