Vacuum Gauge; Face Mounted Instruments Removal And Installation; Vacuum Regulator Valve - Piper PA-44-180 SEMINOLE Maintenance Manual

C. The gyros themselves act as a limiting device to keep the vacuum power applied from exceeding safe
levels.
If the panel gauge has been checked and found OK and the vacuum gauge reading
does not repeat within the range of 5.0 ± .2 inches of mercury then the regulating
valve should be changed. Observe the usual precautions for maintaining system
cleanliness to avoid premature pump service.

VACUUM GAUGE.

The suction gauge is mounted to the right of the right control column, except on S/N 44-95001 and up the
vacuum gauge is located on the upper right hand side of the instrument panel. This gauge is calibrated in inches
of mercury and indicates the differential pressure across the pilot's attitude gyro. As the system becomes clogged
or lines obstructed. the gauge will show a decrease in pressure. Do not reset the regulator until the filter and lines
have been checked. The gauge also has two red malfunction indicator buttons. Whenever vacuum is not available
from one of the vacuum sources. the appropriate red button appears at the face of the gauge.
REMOVAL AND INSTALLATION OF FACE MOUNTED INSTRUMENTS.
Since all instruments are mounted in a similar manner. a description of a typical removal and installation is
provided as a guide. Special care should be taken when any operation pertaining to the instruments is performed
1. Remove the face panel.
2. With the face panel removed. the mounting screws for the individual instruments will be exposed. Remove
the connections to the instruments prior to removing the mounting screws of the instrument to be removed.
3. Installation of the instruments will be in reverse of removal. After the installation is completed and before
replacing the instrument face panel, check all components for security and clearance of the control column.

VACUUM REGULATOR VALVE.

Two vacuum regulator valves that contain filters are incorporated in the system to control vacuum pressure to
the gyro instruments. A manifold check valve assembly assures vacuum if one engine or pump should fail.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
— Note —
— Note —
Tag instrument connections for ease of installation.
2K14
3 7 - 1 4 - 0 0
Page 37-07
Revised: May 15, 1989