Technical data

13773-001
34-20
Page 330 Nov 2000
3. MAINTENANCE PRACTICES
A. Magnetic Compass (See Figure 34-201)
(1) Removal - Magnetic Compass Assembly
WARNING:
When performing maintenance practices on the magnetic compass, use a
non-magnetic or plastic screwdriver.
(a) Ensure BAT 1, BAT 2, and AVIONICS master switches are in off position.
(b) Pull INSTRUMENT LIGHTS circuit breaker.
(c) While supporting compass assembly, remove screws securing compass to bracket.
(d) While supporting compass, loosen forward headliner. (Refer to 25-10)
(e) Disconnect electrical connector.
(f) While supporting compass assembly, remove screws securing compass bracket to cabin
ceiling.
(g) Remove compass assembly from airplane.
(2) Installation - Magnetic Compass
(a) Position compass assembly bracket over mounting holes in fuselage.
(b) Install screws securing compass bracket to cabin ceiling.
(c) Connect electrical connector.
(d) Install forward headliner. (Refer to 25-10)
(e) Reset INSTRUMENT LIGHTS circuit breaker.
(3) Adjustment/Test - Magnetic Compass Calibration
Prior to calibrating compass, place the airplane in as realistic flight environment as possible.
Check to see that the doors are closed, flaps in retracted position, engine running, and airplane
in level flight attitude. Battery Master Switch, Pitot Heat, Alternator Master Switch, and all radio
switches are in the ON position. All other cockpit controlled electrical switches should be in the
OFF position.
WARNING:
When performing maintenance practices on the magnetic compass, use a
non-magnetic or plastic screwdriver.
(a) Remove screws securing access plate to compass housing to reveal adjustment screws.
(b) Set adjustment screws of compensator on zero. Zero position is indicated when dot of
screw is aligned with dot on compass frame.
(c) Taxi airplane to compass rose.
(d) Align centerline of airplane on magnetic North heading. Adjust N-S set screw until com-
pass reads North.
(e) Align centerline of airplane on magnetic East heading. Adjust E-W set screw until com-
pass reads East.
Trouble - Attitude Indicator Probable Cause Remedy
Horizon bar does not settle. Defective instrument. Replace instrument.
Excessive vibration. Tighten mounting screws.
Horizon bar oscillates or vibrates
excessively.
Excessive vibration. Tighten mounting screws.