Cub Crafters CC18-180 Pilot Operating Handbook page 292

SECTION 9.9
SUPPLEMENTS-VACUUM SYSTEM
The vacuum system operates the air driven directional
gyro and the attitude gyro, when installed. Besides the
instruments, the system consists:

An engine driven vacuum pump

A vacuum regulator

A vacuum gauge

A filter

The necessary plumbing
The pump is of the dry type. If the pump should become
obstructed, a shear drive will protect it from damage but
will render the gyroscopic instruments inoperative.
The regulator is set so that the vacuum gauge reads
between 4.8 and 5.2 inches of mercury. Its function is to
protect the gyros.
The vacuum gauge should be monitored periodically
during flight. If a decrease in pressure is noticed (relative
to what the instrument normally reads), then there may
be a dirty filter, dirty screens, a leak in the system or a
problem with the regulator. An inoperative pump, a
defective gauge or a collapsed line could cause the
gauge to read zero. Should this occur at any time, a
qualified mechanic should investigate the cause to
prevent further damage to the system.
REPORT TC10000AFM
Page number 9-9-4
CUB CRAFTERS
CC18-180
Issued 5/31/05
Date of revision: 12/06/05