Pilot's And Copilot's Gyro Installation - With Deicer Boots - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
h.
To adjust the deicer system operating pressure, loosen the locknut on the nacelle mounted
pressure control valve (3) (without an attached solenoid) and rotate the knurled screw clockwise (IN) to
increase pressure or counterclockwise (OUT) to decrease pressure, until the desired pressure setting is
obtained. Tighten the locknut.
i.
Repeat Steps g and h for the right engine (left engine OFF).
j.
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.
k.
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 (16) 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.
1.
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 (16) and, with an Allen wrench, turn
the set screw clockwise (IN) or counterclockwise (OUT) until the desired pressure setting is obtained.
Tighten the locknut.
m. 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 these conditions cannot be met, the gyro control is
defective.
n.
Tighten all adjustment locknuts and install any access panels or covers removed.
10-19. PILOT'S AND COPILOTS GYRO INSTALLATION WITH DEICER BOOTS. (Serial Nos. 31-
7652124 and up) (Refer to Figure 10-4.)
a.
Install a test pressure gauge 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 test gauge tap point remove the cap from the tap fitting and install the test pressure gauge.
NOTE
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 easily observed is
desired. The tap fitting is three-sixteenth straight thread flared.
c.
Operate left engine at 2200 RPM (right engine OFF) and check if the test pressure gauge reads
6.0 psi on the test gauge. Should the reading not be as specified, shut-down the engine and remove the
forward access plate at the top of the nacelle. Adjust the normal pressure regulator of the dual regulator.
The normal pressure regulator incorporates the electrical solenoid. Loosen the adjustment screw jam nut of
the normal pressure regulator of the dual regulators 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.
Reissued: 9/23/80
3A2INSTRUMENTS