Piper PA-32R-301T SARATOGA S, Maintenance Manual

Page: 610 / 956

DISTRIBUTION
VACUUM SYSTEM SERVICE TIPS
The following information is intended to acquaint field service personnel with a means to diagnose vacuum
system service symptoms on those components which are serviced by removal and replacement. These
items include hoses, clamps, gyro filters, vacuum regulating valves and vacuum gauges.
1. Hoses and Clamps:
a. These items should be examined periodically and inspected carefully whenever engine maintenance
activities cause hose disconnections to be made at the pump, regulating valve, gyros and/or vacuum
gauge.
b. Ends of hoses should be examined for rubber separation and slivers of rubber on inside diameter
of hoses. These slivers can and do become detached. If this happens, vacuum pump sucks these
loose particles and eventually ingests them. This can cause premature pump service.
c. Hose clamps and fittings should be replaced when broken, damaged or corroded.
– CAUTION –
When replacing any of the threaded fittings, DO NOT USE
PIPE DOPE or any other anti-seize tape or compound.
AIRBORNE fittings are all cadmium plated to avoid the need
for any other anti-seize materials. The reason for this caution
is to protect pump from ingesting any foreign materials that
could cause premature service.
2. Vacuum Gauges:
a. Vacuum gauges seldom require service and usually are replaced when malfunctions occur.
– NOTE –
Vacuum gauge failure in a properly operating vacuum system does not impair safety of flight.
b. If vacuum gauge malfunctions in a manner to cause an incorrect reading in normal cruise
conditions, gauge must be checked by comparing reading with a gauge of known accuracy. If
gauge is indicating correct values and system vacuum level is not in accordance with specified
vacuum, then and only then should regulator be reset.
c. Visual examination of gauge performance should cover the following steps:
(1) With engine stopped and no vacuum supplied to gauge, its pointer should rest against the the
internal stop in 9 o’clock position. Any other displacement from this position suggests need
for replacement.
(2) A slight overshoot during engine startup, not to exceed half an inch () of mercury, is normal
and is not cause to replace gauge.
(3) With engine operating at normal cruise RPM, gauge should read from 4.8 inches to 5.2 inches
of mercury (vacuum).
(4) At 1200 rpm, vacuum gauge reading should be more than four inches of mercury.
PIPER AIRCRAFT
PA-32R-301/301T
MAINTENANCE MANUAL
37-10-00
Page 37-5
Reissued: July 1, 1993
3G12