PIPER AIRCRAFT, INC.
PA-28-161, WARRIOR III
MAINTENANCE MANUAL
PAGE 4
Nov 30/06
3I24
37-10-00
4. Vacuum
Regulator
One (1) vacuum regulator is incorporated in the system to control vacuum pressure to gyro instruments.
The regulator is located under the instrument panel.
A. Service Tips
(1) Vacuum regulators seldom need replacement. Symptoms that suggest replacement are:
(a) Chatter as indicated by rapid fluctuation of vacuum gauge needle or an audible sound.
(b) Non-repeatability of vacuum gauge reading when panel gauge is not suspect or has been
checked against a known test gauge (cruise RPM only).
(2) All modes of regulator malfunction tend to increase vacuum power applied to gyros. Thus,
although excess vacuum is applied, a loss of vacuum does not occur.
(3) Gyros themselves act as a limiting device to keep vacuum power applied from exceeding safe
levels.
NOTE: If panel gauge has been checked and found OK and vacuum gauge reading does not
repeat within the normal operating range as marked on the gauge, then the vacuum
regulator(s) should be changed. Observe usual precautions for maintaining system
cleanliness to avoid pump failure from ingested debris.
B. Removal and Replacement
(1) Disconnect the three vacuum lines. Mark to facilitate installation.
(2) Disconnect and mark electrical wires.
(3) Remove mounting nut. Remove regulator valve.
(4) Install regulator valve in reverse order of removal.
C. Adjustment
WARNING: DO NOT ATTEMPT ADJUSTMENT OF VACUUM REGULATOR WITH THE ENGINE
IN OPERATION.
NO
TE: Do not reset the regulator until the filter and lines have been checked.
(1) Loosen locking nut or remove protective cap from the valve per type installed.
(2) Start engine. After warm-up, run engine at magneto check rpm
(3) With the engine running at medium rpm, the suction gauge should indicate 4.8 to 5.2 inches of
mercury. If reading is not within this range, shut down engine, and adjust regulator valve by
moving the valve adjustment screw clockwise to increase the pressure and counterclockwise
to decrease the pressure. Start engine and repeat check. With engine running at magneto
check 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 temporary gauge by:
(a) Removing the plug from the back of the attitude deviation indicator.
(b) Install a temporary gauge into the back of the attitude deviation indicator.
(4) Restart engine and repeat check.
(5) After system pressure has been adjusted to the recommended settings, replace the protective
cap or retighten the lock nut per type of valve installed.
(6) If a temporary gauge was used, remove the gauge and install plug into the back of the attitude
deviation indicator.
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