Piper ARCHER II - Vacuum System

PIPER AIRCRAFT CORPORATION SECTION 7
PA-28-181, ARCHER II DESCRIPTION & OPERATION
amount of current shown on the ammeter will tell immediately if the alter-
nator system is operating normally, as the amount of current shown should
equal the total amperage drawn by the equipment which is operating.
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
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 right instrument panel to the right
of the radios, 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.
ISSUED: JULY 2, 1979 REPORT: VB-1120
REVISED: NOVEMBER 15, 1982 7-13