Piper Aircraft Corporation Malibu Mirage PA-46-350P, Airplane Maintenance Manual

Page: 1100 / 1956

PAGE 4
Feb 28/07
6D6
37-10-00
PIPER AIRCRAFT, INC.
PA-46-350P, MALIBU MIRAGE
MAINTENANCE MANUAL
4. Vacuum Regulator(s)
Two (2) vacuum regulators are incorporated in the system to control vacuum pressure to gyro
instruments. The regulators are located above the overhead trim panel in the forward baggage
compartment.
A. Removal
(1) Remove inlet hose from aft side of valve.
(2) Remove outlet hose from forward side of valve.
(3) Remove nut that secures valve to firewall.
(4) Pull valve rearward out of firewall.
B. Installation
(1) Insert valve into hole in rear of firewall.
(2) Secure valve to firewall with nut.
(3) Attach inlet hose to forward fitting of valve.
(4) Attach outlet hose to aft fitting of valve.
C. Service Tips
(1) The vacuum regulating valve seldom needs replacement. Symptoms that suggest replacement
are:
(a) Chatter as indicated by rapid fluctuation of the vacuum gauge needle or an audible sound.
(b) Non-repeatability of the vacuum gauge reading when the 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 the vacuum power applied to the gyros.
Thus, although excess vacuum is applied, a loss of vacuum does not occur.
(3) The gyros themselves act as a limiting device to keep the vacuum power applied from
exceeding safe levels.
NOTE: If the panel gauge has been checked and found “OK” and the vacuum gauge reading
does not repeat within the normal operating range as marked on the gauge, then the
regulating valve should be changed. Observe the usual precautions for maintaining
system cleanliness to avoid premature pump service.
D. Adjustment
NOTE: Do not reset the regulator until the filter and lines have been checked
(1) Disconnect inlet line going to one of the vacuum regulator valves.
(2) Wrap or cap the end of line with a clean, porous cloth to prevent foreign matter and debris from
entering the system.
NOTE: Do not attempt to adjust these valves with the engine in operation without a qualified
pilot or other responsible person at the controls of the airplane.
(3) Start the engine, allow it to warm up and run the engine at magneto check rpm.
(4) While running the engine at magneto check rpm, the suction gauge (or vacuum pressure
indicator) should indicate within the normal operating range as marked on the gauge. If the
reading is not in this range, shut down the engine and adjust the valve. (Turn the valve
adjustment screw clockwise to increase pressure and counterclockwise to decrease pressure.)
(5) Start the engine and repeat the check.
(6) After the system has been properly adjusted, bend the locking tabs on the valve down over the
adjustment screw.