Leak Test Of Selector Valve (Scott); Disassembly Of Crossfeed Valve; Cleaning, Inspection And Repair Of Crossfeed Valve; Fire Wall Shutoff Valve Diagram - Piper Navajo Chieftain PA-31-350 Service Manual

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NAVAJO CHIEFTAIN SERVICE MANUAL
253
252
6
1. WASHER
2. STEM, VALVE
3. BODY, VALVE
4. SEAT, VALVE
25. O-RING
6. O-RING
7. PACKING
8. PIN
9. NUT
10. ARM, CONTROL
11. SEAL. OUTER
12. SEAL, INNER
1. BODY, VALVE
2. VALVE
3. SNAP RING
4. STOP
5. PIN
6. ARM
7. O-RING
8. O-RING
Figure 9-7. Crossfeed Valve
Figure 9-8. Fire Wall Shutoff Valve
9-20. LEAK TEST OF SELECTOR VALVE. (SCOTT.)
a. Connect the inlet port of the valve assembly to a 25 psig air source.
b. Plug the right hand port and close the left hand port by placing the control lever to the right.
c. Apply pressure to 25 psig. There shall be no evidence of leakage either through the port or
around the fitting and lever when submerged in kerosene or a similar petroleum-base fluid for 30 seconds.
d. Depressurize, remove the plug from the right hand port, place on left hand port and close right
hand port by placing the lever to left.
e. Repeat step c.
f. Disconnect and wipe fluid from exterior.
9-21. DISASSEMBLY OF CROSSFEED VALVE. (Refer to Figure 9-7.)
a.
Disconnect the control arm (10) from the valve step (2) by removing nut (9) from the pin (8).
b. Push the stem out of the valve body (3).
c. Remove seal(s) requiring replacement.
d. If seat valve (4) is removed, replace O-ring packing (6).
9-22. CLEANING, INSPECTION AND REPAIR OF CROSSFEED VALVE.
a. Clean the valve components in a suitable cleaning solvent.
b. Inspect the valve for the following:
1. Check that the friction surfaces of the valve body and stem are free from nicks, dents and
burrs.
2.
Check that the inner and outer seals are not worn so much as to allow the valve stem to
misalign in the valve seat. (For replacement of inner and outer seal, return to Scott.)
3. Check that the threaded surfaces of the seat fitting are not stripped or cross-threaded.
c. Repair to the valve is limited to reconditioning of parts, such as smoothing out minor nicks and
scratches, and the replacing of O-ring packings.
Reissued: 9/23/80
FUEL SYSTEM
2K17