Fuel System Troubleshooting; Removal Of Wing Fuel Cells; Removal Of Nacelle Fuel Cell - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
Drains are provided for each fuel cell, filter bowl and the crossfeed line. The cell drains are visible on
the underside of each wing at the inboard end of the cells. The filter bowl drains are accessible through an
access door on the panel that is located between the underside of each wing and the fuselage. The crossfeed
is located on the left panel, aft of the filter bowl access door.
The fuel valves are operated through controls located in a panel at the base of the pedestal. On Serial
Nos. 31-7305118 and up, a warning light has been incorporated on the fuel control panel to indicate when
either shutoff valve is closed. A lock on the fire wall fuel shutoff lever has been designed as a safety feature to
prevent an inadvertent fuel shutoff. Fuel gauges will indicate the quantity of fuel in each cell that fuel is being
drawn from except when the (optional) nacelle fuel cell is installed then the nacelle and (main) inboard fuel
quantity is read off of the same gauge.
9-3. TROUBLESHOOTING. Troubles peculiar to the fuel system are listed in Table IX-II at the back of
this section, along with their probable causes and suggested remedies. When troubleshooting, check from
the fuel supply to the items affected. If no trouble is found by this method, the trouble probably exists
inside individual pieces of equipment; they may then be removed from the airplane and overhauled, or
identical units or units tested and known to be good installed in their place. Troubleshooting the fuel
quantity indicator may be found in Section X, Instruments. The electrical system diagram for the system
may be found in Section XI, Electrical System.
94. FUEL CELLS.
9-5. REMOVAL OF WING FUEL CELLS. (Refer to Figure 9-2 or 9-3.)
a. Turn the fuel selector to the off position and drain the fuel cell. (Refer to Draining Fuel System,
Section II.)
b. From the underside of the wing, remove the access plates to the fuel cell outlet and vent.
c. Loosen the clamp and disconnect the nipple fittings at the fuel outlet at the inboard end of the
cell and vent line at the outboard end of the cell.
d. Remove the screws that secure the drain fitting plate, draw the drain down enough to disconnect
the fitting clamp and remove the drain.
e. On top of the wing, remove the access plates to the fuel cell and senders.
f. Disconnect the wires from the sender units, remove the screws that secure the sender and
carefully draw the sender with gasket from the cell. Note the installed position of the senders.
g. Reach through the access hole and untie the nylon cord that secures the cell.
h. Remove the filler cap and machine screws that secure the cap adapter and gaskets.
i. Remove the cap bolts that secure the adapter bracket to the fuel cell and draw the adapter
bracket out through the elongated access hole, being careful not to damage the cell.
j. Place tape or another protective material around the cell access opening to prevent damage to the
cell when removing.
k. Push the cell down and work the nylon cord back through the cell hangers and rib bushing to the
outboard ends of the cell compartment.
1. Fold the cell neatly within the wing and remove it gently through the opening in the top of the
wing.
9-5a. REMOVAL OF NACELLE FUEL CELL. (Refer to Figure 9-2a.)
a. Turn the fuel selector to the off position and drain the fuel from the cell.
b. Remove the access plates to the fuel cell outlet and fuel sender unit.
c. Loosen the clamps and disconnect the fuel outlet at the forward inboard end of the cell, the vent line
at the forward outboard end of the cell and the drain line from below the cell in the main landing gear wheel
wells.
d.
Disconnect the wires from the sender unit, remove the screws that secure the sender and carefully
draw the sender with gasket from the fuel cell. Note the installed position of the sender for proper rein-
stallation.
Revised: 3/11/81
FUEL SYSTEM
2K5