Piper Arrow IV Turbo Maintenance Manual page 471

2. Secure the pump to the engine with four plain washers, lock washers and retaining nuts. Torque the
nuts 40 to 50 inch-pounds.
3. Connect the hoses to the pump and secure with hose clamps.
4. Reinstall the engine cowling.
VACUUM REGULATOR VALVE.
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.
ADJUSTMENT OF VACUUM REGULATOR VALVE.
1. Loosen the locking nut or remove the protective cap from the valve, depending on which type is
installed.
Do not attempt adjustment of this valve with the engine in
operation, without a qualified pilot or other responsible person at
the controls.
2. Start the engine, after allowing time for warm-up, run the engine at medium RPM.
3. With the engine running at magneto check RPM, the suction gauge should indicate 5.0 inches of
mercury ± .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
magneto check RPM, the suction gauge should indicate 5.0 inches of mercury ± .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.
4. Restart the engine and repeat the check.
5. 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 locknut, whichever applies to the type of valve
installed.
ADJUSTMENT OF VACUUM TURN AND BANK INDICATOR REGULATOR VALVE.
1. To adjust the turn and bank indicator, remove the plug found in the back of the instrument and install
the proper AN fitting that will accommodate a small hose from a suction gauge.
Do not attempt adjustment of any system in this airplane, with the
engine in operation, without a qualified pilot or other responsible
person at the controls.
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL
—NOTE—
—NOTE—
2H24
37-10-08
Page 37-06
Revised: July 24, 1981