Piper Navajo Chieftain PA-31-350 Service Manual page 576

NAVAJO CHIEFTAIN SERVICE MANUAL
d.
Repeat Step c for the right engine (left engine OFF).
e.
To check the deicer system operation pressure, operate left engine at 2500 RPM (right engine
OFF). Actuate the deicer system. The test gauge should read 18.0 ± .5 psi (37 ± 1 in. Hg).
NOTE
The pressure should be read just prior to completion of the cycle.
NOTE
Should the test gauge reading not be within tolerance, first ascertain
that the deicer boots have been pressure tested. (Refer to Paragraph
10-24 for test procedure.)
f.
To adjust the deicer system operating pressure, loosen the locknut on the nacelle mounted dual
regulator. The deicer system pressure regulator is the regulator without the electric solenoid.
g.
Repeat Steps e and f for the right engine (left engine OFF).
h.
To adjust the gyro pressure setting, install a test gauge in the copilot's gyro pressure line. A hypo
needle inserted in the hose from the right side of the gyro control located under the copilot's instrument
panel and connected to a suitable pressure gauge is satisfactory.
i.
Operate both engines at 2200 RPM. The test gauge pressure should read 5.5 + .2 in. Hg (2.7 + .1
psi). To set the pressure, adjust the copilot's side of the pneumatic relay shutoff valve assembly (10) by
loosening the locknut on the right side of the control and, with an Allen wrench, turn the set screw
counterclockwise (OUT) or clockwise (IN) until the desired pressure setting is obtained. Tighten
the
locknut.
j.
With both engines operating at 2200 RPM, the pressure gauge for the pilot's gyros, located on
copilot's instrument panel, should read 5.5 ± .2 in. Hg (2.7
±
.1 psi). To adjust the pressure, loosen the
locknut on the bottom of the pneumatic relay shutoff valve assembly (10) and, with an Allen wrench,
turn
the set screw clockwise (IN) or counterclockwise (OUT) until the desired pressure setting is obtained.
Tighten the locknut.
k.
With both engines operating at 2200 RPM, and with the deicers activated, insure that the pressure
gauge for the pilot's gyros reads 5.5 ±.4 in. Hg (2.7 ± .2 psi).
NOTE
There will be a momentary fluctuation of pressure at the
beginning of boot inflation. Therefore, the pilot's gyro pressure
should be read just prior to completion of the boot inflation cycle.
The air to the copilot's gyros is shut off when the deicer system is
activated. If this condition cannot be met, the pneumatic relay
valve may be defective.
1.
Tighten all adjustment locknuts and install any access panels or covers removed.
Revised: 3/11/81
INSTRUMENTS
3A22