PIPER
SENECA
II
SERVICE
MANUAL
10-39. MAGNETIC COMPASS.
10-40. GENERAL. The magnetic compass
is
a self-contained instrument. This instrument has an individual
light which
is
connected to the instrument lighting circuit. The compass correction card
is
located in the
card holder mounted on the instrument. The compass should be swung whenever instruments or radios are
changed and
at
least once a year.
10-41. ADJUSTMENT OF
COMPASS.
Before attempting to compensate compass, every effort should be
made to place the aircraft in simulated flight conditions; check
to
see
that the doors are closed, flaps in
retracted position, engines running, throttles set at cruise position and aircraft in level flight attitude.
Aircraft master switch, alternator, and radios should
be
on. All other cockpit controlled electrical switches
should be in the
off
position.
a.
Set adjustment screws
of
compensator on zero. Zero position
of
adjusting screws
is
when the
dot
of
the screw is lined up with the
dot
of
the frame.
b. Head aircraft on a magnetic North heading. Adjust
N-S
adjustment screw until compass reads
exactly North.
c.
Head aircraft on a magnetic East heading and do the same
as
Step b, adjusting
E-W
adjusting
screw.
d. Head aircraft on a magnetic South heading and note resulting South error. Adjust
N-S
adjusting
screw until one-half
of
this error has been compensated. No compensation adjustments shall be made with
the combustion heater operating.
e.
Head aircraft on magnetic
West
and do same
as
Step d, adjusting
E-W
adjustment screw.
f.
Head aircraft in successive magnetic
30°
degree headings and record compass readings on
appropriate deviation card. Deviations must
not
exceed±
10° on any heading. An additional deviation card
will have
to
be made
out
for aircraft with combustion heater installed. This second deviation card shall be
accomplished under the above conditions, except the combustion heater shall be operating.
10-4
2.
TROUBLESHOOTING.
TABLE X-VII. MAGNETIC COMPASS
Trouble
Cause
Remedy
Excessive card error.
Compass not properly
Compensate instrument.
compensated.
(Refer
to
Para. 10-41)
External magnetic
Locate magnetic inter-
interference.
ference and eliminate
if possible.
Excessive card Insufficient liquid.
Replace or repair instrument.
oscillation.
Card sluggish.
Weak
card magnet. Replace or repair instrument
Excessive pivot fric-
Replace or repair instrument.
I
tion
or
broken jewel.
I
Reissued:
10/11/79
INSTRUMENTS
1
2F2
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