10-22. VACUUM REGULATOR SETTING - AUXILIARY PUMP OFF
a. The aircraft vacuum regulator should be set to obtain 5.0 ± .2 in. Hg. on the instrument panel vacuum
gage. If adjustment is required perform the following steps.
1. Remove the central air filter.
2. Operate engine at medium =R.P.M. on the ground
3. Adjust regulator to obtain 4.8 to 5.2 in. Hg.
4. Insure that the central air filter is clean. Reinstall the central air filter.
—Note—
If gage reading drops noticeably, install a new central air filter.
—Warning—
The basic aircraft pneumatic system must be properly maintained. If
the vacuum regulator is adjusted to compensate for faults (leaks,
pinched hoses, dirty filters, etc.) in the basic system, both the engine-
driven pump and the auxiliary pump will be subjected to conditions that
may produce high wear and/or premature failure.
10-23 AUXILIARY AIR PUMP FUNCTIONAL CHECK - ENGINE SHUT DOWN.
—Note—
If it is required to run the auxiliary pump for more than a couple of
minutes, it is recommended that the aircraft have an APU connected.
a. Turn aircraft master switch "on".
b. Check the "VAC OFF' side of the auxiliary dry air pump switch to see if it is illuminated. If not,
trouble shoot the wiring system.
—Note—
The switch 'VAC OFF' light and the aircraft annunciator light should
operate simultaneously.
c. Push in auxiliary dry air pump switch to cycle it to the "on" position.
d. Auxiliary pump "AUX ON" light should be illuminated.
e. The "VAC OFF" light should be extinguished shortly after pump is turned on.
f. Check vacuum gage for proper system vacuum 4.8 to 5.2 in. Hg.
g. After the operational check is complete, push in on the auxiliary pump switch to cycle to the "off" position.
h. The auxiliary pump "AUX ON' light should go off.
i. The "VAC OFF' should illuminate.
j. Turn aircraft master switch "off".
k. System operational check is complete.
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
I N S T R U M E N T
2B16