Page 202 2
nd
Edition – Rev 0
34-20
ATTITUDE AND HEATING – MAINTENANCE PRACTICE
2. MAGNETIC COMPASS
Foreword
Any time there is a maintenance or repair to the aircraft, it is recommended that the compass be
compensated. This is particularly true if there is work associated with the removal of old and/or
installation of new equipment in the instrument panel. New radios and relocation of speakers or
intercoms could affect the compensation required.
New hardware (i.e. screws, nuts, etc.) installed during maintenance can sometimes be the cause of
excessive errors if the hardware is steel or magnetic.
Loose electrical grounds, lighting, or extended periods of parking in North-South alignment on the
ramp can lead to the magnetization of the airframe itself. This is often evidenced by excessive
uncompensated compass error (more than 30-35 degrees). Center windshield post becoming
magnetized can lead to compensation problems. Degaussing the airframe component will solve this
problem.
In-flight compensation will achieve the best results.
Operators should consider removing any jewelry while compensating compasses. Such things as
watches, rings, and eyeglasses can affect the amount of compensation required.
If the uncompensated error is in excess of 30-35 degrees, troubleshoot for magnetization of aircraft
components or excessive electrical interference.
Place the calibrated magnetic compass at 10 meters from the a/c nose cone: make sure that
area is not affected from magnetic materials likely to influence compass deviation
Tools
Calibrated magnetic compass
Mod. 606629/009 by SIRS or equivalent
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