Piper COMANCHE PA-24-180 Service Manual page 667

PIPER COMANCHE SERVICE MANUAL
11-24 Removal And Replacement. Refer to Paragraph 11-1 of this ecnon.
11-25 Troubleshoodng.
TABLE XI-ll. DIRECTIONAL GYRO INDICATOR
Trouble
Excess dnft m either
direction.
Cause
Excesive vibration with
amplitude more than
0.006 inch.
insufficient vacuum. If
vacuum below 4.2 inch hg.,
check for the following:
a. Relief valve improperly
adjusted.
b. Incorrect gauge reading.
c. Pump failure.
d. Vacuum line kinked or
leaking.
Remedy
Check shock mounts.
a. Adjust.
b. Recalibrate.
c. Repair or replace.
d. Check and repair.
Check for collapsed
inner wall of hose
Defective instrument.
Replace instrument.
Dial spins continuouslv.
Defective mechanism.
Replace.
11-26 Gyro Horizon.
11-27 General. The gyro horizon is essenially an air driven gyroscope rotaring in a honzontal plane and i,
operated bv the same principal u the directional gyro. Due to the gyroscopic inertia the spin aLs
continues to point in the vertical direction, providing a constant visual reference to the attitude of the
airplane relative to pitch and roll axis. A bar across the face of the indicator represents the horizon. A
miniature adjustable airplane is mounted to the cse and aligning the miniature airplane to the horiron bar
simulates the alignment of the airplane to the actual horizon. Any deviation simulates the devianton of the
airplane from the true horizon. The gyro horizon is marked for different degrees of bank
11-28 Removal And Replacement. Refer to Paragraph 11-18 of this secon.
INSTRUMENTS
ISSUED: 8/18/72
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