Piper Arrow IV Turbo Maintenance Manual page 441

CHART 3405. TROUBLESHOOTING (DIRECTIONAL GYRO INDICATOR)
Trouble
Excess drift in either
direction.
Dial spins during turn.
Dial spins continuously.
MAGNETIC COMPASS.
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.
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, engine running, throttle set
at cruise position and aircraft in level flight attitude. Aircraft master switch, alternator switch and all radio
switches should be in the ON position. All other cockpit controlled electrical switches should be in the OFF
position.
1. 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.
2. Head aircraft on a magnetic North heading. Adjust N-S adjustment screw until compass reads exactly
North.
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL
Cause
Setting error.
Defective instrument.
High or low vacuum. If
vacuum is not correct,
check for the following:
1. Relief valve improperly
adjusted.
2. Incorrect gauge reading.
3. Pump failure.
4. Vacuum line kinked or
leaking.
Limits (55° bank) of gimbal
exceeded.
Defective mechanism.
2G18
Remedy
Review paragraph titled
"General" for gyro op-
eration.
Replace instrument.
1. Adjust.
2. Replace gauge.
3. Repair or replace.
4. Check and repair. Check
for collapsed inner wall
of hose.
Recage gyro in level flight.
Replace.
34-10-07
Page 34-10
December 1, 1978