Pilot's Gyros And Copilot's Gyros; Deicer Boots Pressure Test - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
10-22. PILOT'S GYROS AND COPILOT'S GYROS. (Refer to Figure 10-7 or 10-8.)
a. Close the center regulator located under the instrument panel by loosening the locknut and
turning the knurled adjustment screw clockwise (IN) as far as possible.
b. Operate the right engine at 2200 RPM (left engine OFF). The pressure gauge mounted in the
instrument panel should read 6.0+ .3 in. Hg (2.9+ .15 psi).
c. To adjust the pressure, loosen the locknut on the regulator mounted in the nacelle and rotate the
knurled screw clockwise (IN) or counterclockwise (OUT) to obtain the desired pressure setting. Tighten the
locknut.
d.
Repeat Steps a thru c with the left engine operating and the right engine shutdown.
e. With both engines operating at 2200 RPM, adjust the center regulator (under the instrument
panel) until the instrument panel pressure gauge reads 5.5
.2 in. Hg (2.7 .1 psi). Adjustment procedure
for the regulator is the same as Step c above.
10-23. PILOT'S GYROS. (Refer to Figure 10-9 or 10-10.)
a. Operate the right engine at 2200 RPM with the left engine shutdown. The instrument panel
pressure gauge should read 5.5 ± .2 in. Hg (2.7 ± .I psi).
b. To adjust the pressure, loosen the locknut on the regulator in the nacelle and rotate the knurled
screw clockwise (IN) or counterclockwise (OUT) until the desired pressure setting is obtained. Tighten the
locknut.
c. Repeat Steps a and b with the left engine operating and the right engine shutdown.
d.
With both engines operating at 2200 RPM, insure that the pressure gauge reads 5.5 + .4 in. Hg
(2.7 +.2 psi).
10-24. DEICER BOOTS PRESSURE TEST.
a.
Use a source of clean air, which can be regulated between 18 and 20 psi, along with a testing rig
consisting of:
1. Adjustable regulator.
2.
Pressure regulator.
3. Shutoff valve.
NOTE
The shutoff valve must be connected so as to trap air in the deicer
system.
b.
Disconnect the line to the pressure regulator. Attach the test rig on the line to the pressure
regulator. On aircraft with Serial Nos. 31-5001 to 31-7652123, bypass the three ejector flow control valves
by disconnecting lines to these valves and installing temporary test lines. On aircraft with Serial Nos.
31-7652124 and up, bypass the one ejector valve and install temporary test line. Apply 19 psi of air to the
system, and using the shutoff valve, trap this air pressure in this portion of the system. A soap solution may
be used to check for leakage, which should not exceed 3 psi per minute.
c.
Check the pressure switch operation with the deicer system under pressure, while the battery
switch is in the ON position; the indicator light will glow.
d.
With the master switch ON and the deicer control switch in the OFF position, press the indicator
light to check the circuit and light bulb. If the indicator light does not function, check and reset the circuit
breaker; a short may exist.
e. Remove the test rig, lubricate the threads, replace and tighten items dismantled.
f. With boots pressure test completed, recheck system pressure as given in Paragraph 10-18 or
Paragraph 10-19.
Reissued: 9/23/80
INSTRUMENTS
3B6