Piper Arrow IV Turbo Maintenance Manual page 439

CHART 3403. TROUBLESHOOTING (AIRSPEED TUBES AND INDICATOR) (cont)
Trouble
Instrument reads low.
Airspeed changes as aircraft
is banked.
When any connections in the static system are opened for
checking, system must be checked per F.A.R. 23.1325.
GYRO HORIZON.
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.
CHART 3404. TROUBLESHOOTING (GYRO HORIZON INDICATOR)
Trouble
Bar fails to respond.
Bar does not settle.
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL
Cause
Pointer not on zero.
Leaking static system.
Pitot head not aligned
correctly.
Water in pitot line.
—NOTE—
Cause
Insufficient vacuum.
Filter dirty.
Insufficient vacuum.
Incorrect instrument.
Defective instrument.
2G16
Remedy
Replace instrument.
Find leak and correct.
Realign pitot head.
Remove lines from static in-
struments and blow out lines
from cockpit to pitot head.
Remedy
Check pump and tubing.
Clean or replace filter.
Check line and pump.
Adjust valve.
Check part number.
Replace.
34-10-04
Page 34-08
December 1, 1978