Directional Gyro Indicator Troubleshooting; Gyro Horizon - Piper PA-24 Comanche Service Manual

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P'PER COMANCHE SERVICE MANUAL
11·24. Removal And Replacement. Refer to Paragraph 11·lS of this secrion.
11·25. Troubleshooan•.
TABLE XI-II. DIRECTIONAL GYRO INDICATOR
TroulHc
c....
Remedy
Excess drift in either Excessive vibration with Check shock mounts.
direenen. amplitude more than
0.006 inch.
Insufficient vacuum. If
vacuum below 4.2 inch
hJ..
check for the followina:
a. Relief valve improperly a. Adjust.
adjusted.
b. Incorrect pUle readina.
b. Rec:aJibrate.
c. Pump failure.
c. Repair or replace.
d. Vacuum line kinked or d. Check and repair.
leaking.
Check for collapsed
inner wall of hose.
Defective instrUment.
Replace insmament.
Dial spins continuously.
Defective mechanism. Replace.
11·26. Gyro Horizon.
11·27. General. The IYro horizon is essentially an air driven IYtOscope toutinr in a horizontal plane and is
oper.1ted by the same principal u the directional gyro. Due to the JY1'OlCopic inertia. the spin axis
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 airt'lane is mounted to the cue and aligning the miniature airplane to the henzen bar
simulates tht alignment of the airplane to the actUal horizon. Any deviation simulates the devianen of the
airplane from the true horizon. The gyro horizon is marked for different degrccs of bank.
11-28. Removal And Replacement. Re!er to Paragraph 11·18 of this section.
INSTRUMENTS
ISSUED: 8/t8/72
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