10-34. REMOVAL AND REPLACEMENT. (Refer to Paragraph 10-87 of this section.)
10-35. GYRO HORIZON.
10-36. GENERAL.
The gyro horizon is essentially an air driven gyroscope rotating in a horizontal plane and is operated by the
same principal as the directional gyro. Due to the gyroscopic 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 and aligning the miniature airplane to the horizon bar
simulates the alignment of the airplane to the actual horizon. Any deviation simulates the deviation of the
airplane from the true horizon. The gyro horizon is marked for different degrees of bank.
10-37. TROUBLESHOOTING.
TABLE X-III. GYRO HORIZON INDICATOR
Trouble
Cause
Remedy
Bar fails to respond.
Insufficient vacuum.
Check pump and tubing.
Filter dirty
Clean or replace filter.
Bar does not settle.
Insufficient vacuum.
Check lines and pump .Adjust valve.
Incorrect instrument.
Check part number.
Defective instrument.
Replace.
Bar oscillates or
Instrument loose in
Tighten mounting screws.
shimmies continuously.
panel.
Vacuum too high
Adjust valve.
Defective mechanism.
Replace instrument.
Instrument does not
Instrument not level in
Loosen screws and level
indicate level flight.
panel. instrument.
Aircraft out of trim
Trim aircraft.
Bar high after 180o
Normal, if it does not
turn
exceed 1/16 inch.
Instrument tumbles in flight.
Low vacuum.
Reset regulator
Dirty filter.
Clean or replace filter.
Line to filter restricted.
Replace line.
Plug missing or loose
Replace or tighten plug.
in instrument
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
I N S T R U M E N T
2B22