Pneumatic System Description; Pneumatic System Filter Replacement - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
10-8. PNEUMATIC SYSTEM. (Refer to Figure 10-3.) (Refer to Paragraph 1460.)
10-9. DESCRIPTION. The PA-31-350 uses a dry pneumatic pump system consisting of two engine driven
pneumatic pumps, pressure control valves, inline filters, pressure switches, check valves, pneumatic relay
and necessary tubing, hoses and connections. The system.operates at preset pressures, depending on the
particular system and equipment installed in the airplane. Gyro pressure is read on a gauge located in the
right side of the instrument panel. Should one of the pressure pumps fail this would be indicated at the
pneumatic source malfunction lights below the pressure gauge.
10-10. PNEUMATIC
SYSTEM FILTER REPLACEMENT.
There are four pneumatic system filters
located throughout the pneumatic system. Two inlet filters (IJ 1-3) located on the inlet side of the pneumatic
pumps and two inline filters (1J4-6) located along the outlet side of the pneumatic pumps. The following
instructions will cover the removal and installation of these filters along with recommended replacement
times as required:
a. Removal of inlet air filters (IJ 1-3) located in the outboard sides of the left and right engine
nacelles aft of the fire wall. above the air inlet opening.
I. Remove the appropriate access panel on the engine nacelle. (Refer to Figure 2-3 of Section
II.) The left nacelle access panel may have the ice detection light while the right access panel is a grill type
panel.
2. Disconnect the hose clamp and remove the hose from the filter.
3.
Remove the locking nut from the filter line and remove the filter.
NOTE
The filter should be replaced at each 100 hour inspection. Refer
to PA-31-350 Parts Catalog for correct part number.
h. Installation of inlet air filter (IJ 1-3).
1. Place the filter in the same position as it was prior to removal and secure with the locking
nut.
2. Connect the hose to the filter and secure with hose clamp.
3. Install and secure access panels previously removed.
c. Removal of inline filter (IJ4-6) located aft of the fire wall in both the left and right engine
nacelle.
1. Remove the appropriate access panel on the upper section of the engine nacelle. (Refer to
Figure 2-3 of Section II.)
2. Disconnect the hose clamps and remove the appropriate filter from the line connection.
NOTE
The filters are the disposable type and shall be replaced by new
ones every 500 hours. Refer to PA-31-350 Parts Catalog for
correct part number.
d. Installation of inline filter ( J4-6). The filter has an arrow on the case indicating the direction of
air flow, and should be installed in the exact position of the old filter.
1. Place the new filter in the engine nacelle aft of the fire wall and connect the air lines to the
filter and secure with hose clamps.
2. Install and secure the access panel previously removed.
Revised: 10/15/82
INSTRUMENTS
3A15