Specifications

CESSNA SECTION 7
MODEL 172R NAV III AIRPLANE AND SYSTEM DESCRIPTION
GFC 700 AFCS
U.S.
VACUUM SYSTEM AND INSTRUMENTS
The vacuum system, Refer to Figure 7-9, provides the vacuum
necessary to operate the standby attitude indicator. The system
consists of one engine-driven vacuum pump, a vacuum regulator, the
standby attitude indicator, a vacuum system air filter, and a vacuum
transducer. The vacuum transducer provides a signal to the engine
display that is processed and displayed as vacuum on the EIS ENGINE
page. If available vacuum, from the engine-driven vacuum pump, drops
below 3.5 in.hg., the LOW VACUUM annunciator will display in amber
on the PFD.
ATTITUDE INDICATOR
The standby attitude indicator is a vacuum-powered gyroscopic
instrument, found on the center instrument panel below the MFD. The
attitude indicator includes a low-vacuum warning flag (GYRO) that
comes into view when the vacuum is below the level necessary for
reliable gyroscope operation.
VACUUM INDICATOR
The vacuum indicator is incorporated on the EIS ENGINE page, found
along the left side of the PFD during engine start or the left edge of the
MFD during normal operation. During reversionary operation, the EIS
bar appears along the left side of the operational display.
LOW VACUUM ANNUNCIATION
A low vacuum condition is annunciated along the right side of the PFD
by a amber LOW VACUUM annunciator.
172RPHBUS-00
7-65