Single Or Dual Attitude And Directional Gyro Installation With H-14 Autopilot - Piper Navajo PA-31 Service Manual

PIPER NAVAJO SERVICE MANUAL
(f) With the engines operating at 2200 rpm, and with the deicer system
energized, insure that the pressure gauge for the pilot gyros reads 5.5
.4
inches of mercury. (2.7
.2 psi.)
NOTE
There will be a momentary fluctuation of pressure at the
beginning of boot inflation.
Therefore,
the pilot gyro
pressure should be read just prior to completion of boot
inflation. The air to the co-pilot's gyros is shutoff during
boot inflation.
If this condition cannot
be met, the
pneumatic relay valve may be defective.
n. Tighten adjustment valve jam nuts, pneumatic relay valve lockscrew, and install
access plates.
10-20. SINGLE OR DUAL ATTITUDE AND DIRECTIONAL GYRO INSTALLATION
WITH H-14 AUTOPILOT. (Refer to Figure 10-6.)
a. Remove the access plate to the pneumatic system test gauge tap point by removing
the left aft plate at the top of the right engine nacelle.
b. At the pneumatic manifold in the left side of the nacelle remove the cap from the
tap fitting and install pressure gauge. An accurate gauge with a range from 0 to 20 psi with a
hose long enough to allow the face of the gauge to be observed from the cockpit is desired.
The tap fitting is three-sixteenth straight thread flared. (Refer to Figure 10-5.)
c. Operate one engine at 2500 rpm and check if the pressure gauge at the nacelle reads
10
.25 psi. Should the reading not be within tolerance, shutdown the engine and remove
the forward access plate on the top of the nacelle. Loosen the adjustment screw jam nut of
the regulator in the right side of the nacelle and turn the screw clockwise to increase
pressure and counterclockwise to decrease pressure. Tighten adjustment screw jam nut.
d. Repeat the preceding step for the other engine.
e. Operate both engines at 2500 rpm and check that the pressure gauge at the nacelle
reads 10 ± .50 psi.
f.
With both engines operating at 2500 rpm, check if pressure gauge located in the
right side of the instrument panel indicates 5.7 inches of mercury.
g. Should the gauge not indicate the correct reading, adjust the pneumatic relay valve
located forward of the instrument panel above the control pedestal. (Refer to Figure 10-7.)
To adjust the relay valve, loosen the locking screw on the side of the relay valve with an
Allen wrench, and turn the adjusting screw to obtain a correct reading. This adjustment may
be made with engines operating.
h. Tighten adjustment valve jam nuts, pneumatic relay valve lockscrew, and install
access plates.
Reissued: 10/12/79
INSTRUMENTS
3D13