Piper Comanche PA-24 Service Manual page 637

and disconnect the wiring.
d. Remove the floor carpet and floor panel covering the selector.
e. Disconnect the fuel lines.
f. Remove the screws securing the valve mounting plate. The forward screws are secured by nuts
while the aft screws are secured by plate nuts. Remove the valve from the aircraft.
8-14. Servicing Three Position Fuel Valve. (PA-24-180 and PA-24-250)
The three position valve should be serviced every 400 hours, annually, or whenever there is an indication
of valve binding. The binding of this valve (refer to Figure 8-11) is caused by fuel coming in contact
with the plug and gradually removing the film of lubricant: presence of foreign material or the use of
improper lubricants.
a. For airplanes equipped with original equipment metal plug fuel selector valves P/N's 11383-000,
11383-002, 11383-003 or 11383-004 inspect as follows:
1. With the valve removed from the aircraft, remove the valve cap (1) and interior parts.
2. Inspect the position washer (7) inner perimeter surface for indications of extreme wear: should
this be evident, replace washer.
3. Check the condition of plug cock (10) and valve body (11) for scored surfaces. The surfaces, if
not badly scored, may be conditioned by lapping with a fine grinding compound. Clean away
all compound after lapping. If plug cock will not seat properly or if scoring remains evident,
the valve should be replaced. See Parts Catalog, P/N 752-464.
4. Check the condition of the valve stem in the area where the "O"-ring (3) seats. Should the stem
be worn or damaged so that the "O"-ring will not seal, replace the valve.
5. With a 10X magnifying glass, inspect the valve plug cock for cracks. If cracks are visible,
replace valve.
6. Clean the valve of all foreign matter, lubricate the dry plug with a light film of SAE-AMS-G-
6032 grease, turn the plug several times in its seat and wipe off any excess lubricant in the plug
cock and valve ports. Lubricate position washer with a light film of SAE-AMS-G-6032 grease.
Reassemble the valve with a new "O"-ring.
7. Rotate fuel selector to check for smooth operation and to insure proper seating in detent
positions.
8. Before reinstalling the valve, it should be checked for leaks and correct operation using 50 PSI
air pressure.
NOTE: If valve is submerged in water for test, insure all water is removed before installation.
9. After reinstallation of valve, check operation and for fuel leaks.
04/01/09
PIPER COMANCHE SERVICE MANUAL
2J3
VIII - FUEL SYSTEM