Cessna 150 Series Service Manual page 157

12-5. FUEL TANKS.
NOTE
12-6. DESCRIPTION.
A rigid metal tank is installed
Remember that a plugged vent line or bleed
in the inboard panel of each wing.
Sump drain plugs hole can cause either fuel starvation and
or valves, one in each tank, are provided for draining
collapsing of fuel tanks or the pressuriza-
trapped water and sediment.
tion of tanks by fuel expansion.
12-7. REMOVAL AND INSTALLATION.
e. Any fuel vent found plugged or restricted must
a. Remove sump drain plug or valve and drain fuel
be corrected prior to returning aircraft to service.
from applicable tank. (Observe precautions outlined
in paragraph 12-3.)
NOTE
b. Remove fuel tank cover by removing attaching
screws. The fuel vent line protruding beneath the wing
c. Remove wing root fairings.
near the wing strut must be correctly aligned
d. Disconnect and plug or cap all fuel and vent lines
to avoid possible icing of the vent tube. Di-
from tank. Remove fittings as necessary for clear- mensions are shown in figure 12-4.
ance when removing tank.
e. Disconnect electrical lead and ground strap from
12-12. FUEL SHUT-OFF VALVE. (See figure 12-2.)
fuel quantity transmitter.
f. Disconnect straps securing fuel tank and remove 12-13. DESCRIPTION.
The fuel shut-off valve is a
tank. Use care to avoid damage to protruding fittings
two-position ON-FF valve, located in the floor area
and hose connections when removing the tank. between the pilot and copilot positions. Thru 1972
g. To install tank, reverse the preceding steps. Be Models, the handle is safetied to the lower mounting
sure grounding is secure in accordance with figure bolt. Beginning with 1973 Models, the handle is sa-
12-3. fetied to a bolt, located in the floorboard. The han-
dle is safetied in the "ON" position with . 018" dia-
12-8. FUEL QUANTITY TRANSMITTERS.
Fuel meter mild steel wire (tag wire), which will break
quantity transmitters are installed in the top of fuel easily if the handle must be turned OFF in an emer-
tanks. A complete description, along with proce-
gency. It is recommended that the valve be replaced
dures for removal, installation and adjustment are
and not repaired.
contained in Section 15.
12-14. REMOVAL AND INSTALLATION.
12-9.
FUEL VENTS.
a. Completely drain all fuel from wing tanks, fuel
lines, strainer, and shut-off valve. (Observe the
12-10. DESCRIPTION. A vent line is installed in the
precautions in paragraph 12-3.)
outboard end of the left fuel tank and extends over-
b. Remove shut-off valve handle.
board down through the lower wing skin. The inboard c. Remove copilot's seat and access plate under
end of the vent line extends into the fuel tank, then seat.
forward and slightly upward. A vent valve is installed
d. Disconnect and cap all fuel lines at shut-off valve.
on the inboard end of the vent line inside the fuel tank,
e. Remove bolts attaching shut-off valve and remove
and a crossover vent line connects the two tanks for valve.
positive ventilation. f. Reverse the preceding steps for installation.
Safety wire valve handle in "ON" position.
12-11. CHECKING. Field experience has demon-
strated that the fuel vent can become plugged, with 12-15. FUEL STRAINER. (See figure 12-5.)
possible fuel starvation of the engine or collapse of
the fuel tanks. Also, the bleed hole in the vent valve 12-16. DESCRIPTION. The fuel strainer is mounted
assembly could possibly become plugged, allowing
at the firewall in the lower engine compartment. The
pressure from expanding fuel to pressurize the tanks. strainer is equipped with a quick-drain valve which
The following procedure may be used to check the provides a means of draining trapped water and sedi-
vent and bleed hole in the valve assembly.
ment from the fuel system. The quick-drain control
a. Attach a rubber tube to the end of vent line be- is located adjacent to the oil dipstick and is accessible
neath the wing. through the oil dipstick door.
b. Blow into tube to slightly pressurize the tanks.
If air can be blown into tanks, vent line is open.
NOTE
c.
After tank is slightly pressurized, insert end of
rubber tube into a container of water and watch for
The fuel strainer can be disassembled, cleaned
a continuous stream of bubbles, which indicates the
and reassembled without removing the assembly
bleed hole in valve assembly is open and relieving
from the aircraft. (Refer to paragraph 12-20.)
pressure.
d. After completion of step "c", blow into tube 12-17. DISASSEMBLYAND ASSEMBLY.
(See figure
again to slightly pressurize the tank, and loosen, 12-5. )
but do not remove filler cap on opposite wing to
a. Remove drain tube, safety wire, nut and washer
check tank crossover line. If pressure escapes
at bottom of filter bowl, and remove bowl.
from filler cap, crossover line is open.
b. Carefully unscrew standpipe and remove.
c. Remove filter screen and gasket.
Wash filter
screen and bowl with solvent (Federal Specification
12-6