—CAUTION—
DO NOT use pipe tape, thread dope, hydrocarbon oil or grease, as these can
contaminate the pump and cause malfunction.
d. With the pump properly secured in the vise, insert fittings in ports and hand tighten firmly.
e. Using a wrench, tighten each fitting from one-half to two additional turns.
10-18. INSTALLATION OF VACUUM PUMP
a. Place the pump gasket in its proper place and align the spline on the pump drive with the spline on the
engine drive assembly.
—CAUTION—
The only pump mounting gasket authorized and approved for use on
the Airbome vacuum pump is the Airbome gasket B3-1-2, Piper part
number 751 859. Use of any other gasket may result in oil seepage or
leakage at the mounting surface.
b. Secure the pump to the engine with four plain washers, lock washers and retaining nuts. Torque the nuts
40 to 5O inch-pounds.
c. Connect the hoses to the pump and secure with hose clamps.
d. Reinstall the engine cowling.
10-19. AUXILIARY VACUUM PUMP.
10-20 GENERAL.
The auxiliary dry air pump system provides an independent backup source of pneumatic power to operate
the gyro flight instruments in the event the engine driven air pump fails. The system consists of a 14 VDC
electrically driven dry air pump that connects to the pneumatic system through a manifold downstream of the
vacuum regulator. Isolation of the auxiliary from the primary system is provided by check valves in the
manifold. The pump is controlled through a panel mounted switch that also incorporates annunciator lights to
inform the pilot of the system operational status. Accumulated pump operating time is recorded by an elapsed
time indicator installed under the instrument panel.
—note—
Poor system installations and maintenance practices will reduce the
maximum altitude at which a given vacuum can be obtained
10-21. SYSTEM ADJUSTMENT AND FUNCTIONAL CHECKS.
—Note—
In-service time for the 4A3- 1 auxiliary pump/motor assembly is limited
to 500 hours actual pump operating time (established by the elapsed
time indicator) or 10 years whichever occurs first. Under normal usage,
500 hours of pump operating time is equivalent to 8000 or more aircraft
operating hours
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
I N S T R U M E N T
2B15