3. With the pump properly secured in the vise, insert fittings into the ports and hand tighten firmly; then
using a wrench, tighten each fitting from one-half to two additional turns.
—NOTE—
Do not use pipe tape, thread dope, hydrocarbon oil or grease, as these
can contaminate the pump and cause malfunction.
10-5. TROUBLESHOOTING. (Refer to Table X-l of this section.)
10-6. SUCTION GAUGE.
10-7. GENERAL. The suction gauge is mounted in the right side of the instrument panel above the hour meter.
This gauge is calibrated in inches of mercury and has a direct pressure line and vent line. Therefore,the gauge
indicates the differential pressure or actual pressure being applied to the gyro instruments. As the system filter
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.
10-8. TROUBLESHOOTING. For troubleshooting of this instrument, refer to Table X-I of this section.
10-9. VACUUM REGULATOR VALVE
10-10. GENERAL. One vacuum regulator valve is incorporated in the system to control vacuum pressure to the
gyro instruments. The regulator valve is located under the instrument panel. Access to the valve for maintenance
and adjustment is gained from below the instrument panel.
10-11. TROUBLESHOOTING. For troubleshooting of the vacuum regulator, refer to Table X-I.
10-12. ADJUSTMENTS OF VACUUM REGULATOR VALVE.
a. Loosen the locking nut or remove the protective cap from the valve. depending on which type is installed .
—NOTE—
Do not attempt adjustment of this valve with the engine in operation .
b. Start the engine. after allowing time for warm-up, run the engine at medium RPM.
c. With the engine running at medium RPM, the suction gauge should indicate 4.8 to 5.2 inches of mercury.
If the pressure reading fails to fall within this range, shut down the engine and adjust the regulator valve by
moving the valve adjustment screw clockwise to increase the pressure, and counterclockwise to decrease the
pressure. Start the engine and repeat the check. With engine running at medium RPM, the suction gauge should
indicate 4.8 to 5.2 inches of mercury. If the airplane is not equipped with a suction gauge. it will be necessary to
connect a gauge by removing the plug from the back of the artificial horizon, and attaching a temporary gauge.
d. Restart the engine and repeat the check.
e. After the system pressure has been adjusted to these recommended settings, remove the gauge and install
the plug, replace the protective cap or retighten the lock nut. whichever applies to the type of valve installed .
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
I N S T R U M E N T
2B11
