Vacuum System - Piper ARCHER III Pilot Operating Handbook

SECTION 7
DESCRIPTION & OPERATION
CAUTION: Do not use cigar lighter receptacles as power
sources for any devices other than the cigar lighters supplied
with the airplane. Any other device plugged into these
receptacles may be damaged.
For abnormal and/or emergency operation and procedure, see Section 3.

7.17 VACUUM SYSTEM

The vacuum system is designed to operate the air driven gyro instru-
ments. This includes the directional and attitude gyros when installed. The
system consists of an engine driven vacuum pump, a vacuum regulator, a filter
and the necessary plumbing.
The vacuum pump is a dry type pump which eliminates the need for an
air/oil separator and its plumbing. A shear drive protects the pump from
damage. If the drive shears, the gyros will become inoperative.
The vacuum gauge, mounted on the left instrument panel (refer to figure
7-15), provides valuable information to the pilot about the operation of the
vacuum system. A decrease in pressure in a system that has remained
constant over an extended period may indicate a dirty filter, dirty screens,
possibly a sticking vacuum regulator or leak in system (a low vacuum
indicator light is provided in the annunciator panel). Zero pressure would
indicate a sheared pump drive, defective pump, possibly a defective gauge or
collapsed line. In the event of any gauge variation from the norm, the pilot
should have a mechanic check the system to prevent possible damage to the
system components or eventual failure of the system.
REPORT: VB-1611
7-12
CIRCUIT BREAKER PANEL
Figure 7-13
PA-28-181, ARCHER III
ISSUED: JULY 12, 1995