Cessna 150K - Fuel Tank Removal and Installation; Fuel Shut-Off Valve Maintenance; Fuel Strainer Maintenance

12-5. FUEL TANKS.
12-6. DESCRIPTION. A rigid metal tank is installed
I
in the inboard panel of each wing. Sump drain plugs
or valves, one in each tank, are provided for draining
trapped water and sediment.
12-7. REMOVAL AND INSTALLATION.
• a. Remove sump drain plug or valve and drain fuel
from applicable tank. (Observe precautions outlined
in paragraph 12 -3. )
b. Remove fuel tank cover by removing attaching
screws.
c. Remove wing root fairings.
d. Disconnect and plug or cap all fuel and vent lines
from tank. Remove fittings as necessary for clear-
ance when removing tank.
e. Disconnect electrical lead and ground strap from
fuel quantity transmitter.
f. Disconnect straps securing fuel tank and remove
tank. Use care to avoid damage to protruding fittings
and hose connections when removing the tank.
g. To install tank, reverse the preceding steps. Be
sure grounding is secure in accordance with figure
12-3.
12-8.
FUEL QUANTITY TRANSMITTERS. Fuel
quantity transmitters are installed in the top of fuel
tanks. A complete description, along with proce-
dures for removal, installation and adjustment are
contained in Section 15.
12-9. FUEL VENTS.
12-10. DESCRIPTION. A vent line is installed in the
outboard end of the left fuel tank and extends over-
board down through the lower wing skin. The inboard
end of the vent line extends into the fuel tank, then
forward and slightly upward. A vent valve is installed
on the inboard end of the vent line inside the fuel tank,
and a crossover vent line connects the two tanks for
positive ventilation.
12-11. CHECKING. Field experience has demon-
strated that the fuel vent can become plugged, with
possible fuel starvation of the engine or collapse of
the fuel tanks. Also, the bleed hole in the vent valve
assembly could possibly become plugged, allowing
pressure from expanding fuel to pressurize the tanks.
The following procedure may be used to check the
vent and bleed hole in the valve assembly.
a. Attach a rubber tube to the end of vent line be-
neath the wing.
b. Blow into tube to slightly pressurize the tanks.
If air can be blown into tanks, vent line is open.
c. After tank is slightly pressurized, insert end of
rubber tube into a container of water and watch for
a continuous stream of bubbles, which indicates the
bleed hole in valve assembly is open and relieVing
pressure.
d. After completion of step "c", blow into tube
again to slightly pressurize the tank, and loosen,
but do not remove filler cap on opposite wing to
check tank crossover line. If pressure escapes
from filler cap, crossover line is open.
NOTE
Remember that a plugged vent line or bleed
hole can cause either fuel starvation and
collapsing of fuel tanks or the pressuriza-
tion of tanks by fuel expansion.
e. Any fuel vent found plugged or restricted must
be corrected prior to returning aircraft to service.
NOTE
The fuel
vent line protruding beneath the wing
near the wing strut must be correctly aligned
to avoid possible icing of the vent tube. Di-
mensions are shown in figure 12-4.
12-12. FUEL SHUT-OFF VALVE. (See figure 12-2.)
12-13. DESCRIPTION. The fuel shut-off valve is a
two-position ON-OFF valve, located in the floor area
between the pilot and copilot positions. Thru 1972
Models, the handle is safetied to the lower mounting
bolt. Beginning with 1973 Models, the handle is sa-
fetied to a bolt, located in the floorboard. The han-
dle is safetied in the "ON" position with. 018" dia-
meter mild steel wire (tag wire), which will break
easily if the handle must be turned OFF in an emer-
gency. It is recommended that the valve be replaced
and not repaired.
12-14. REMOVAL AND INSTALLATION.
a. Completely drain all fuel from wing tanks, fuel
lines, strainer, and shut-off valve. (Observe the
precautions in paragraph 12-3. )
b. Remove shut-off valve handle.
c. Remove copilot's seat and access plate under
seat.
d. Disconnect and cap all fuel lines at shut-off valve.
e. Remove bolts attaching shut-off valve and remove
valve.
f. Reverse the preceding steps for installation.
Safety wire valve handle in "ON" position.
12-15. FUEL STRAINER. (See figure 12-5.)
12-16. DESCRIPTION. The fuel strainer is mounted
at the firewall in the lower engine compartment. The
strainer is equipped with a quick-drain valve which
provides a means of draining trapped water and sedi-
ment from the fuel system. The quick-drain control
is located adjacent to the oil dipstick and is accessible
through the oil dipstick door.
NOTE
The fuel
strainer can be disassembled, cleaned
and reassembled without removing the assembly
from the aircraft. (Refer to paragraph 1~-20. )
12-17. DISASSEMBLY AND ASSEMBLY. (See figure
12-5.)
a. Remove drain tube, safety Wire, nut and washer
at bottom of filter bowl, and remove bowl.
b. Carefully unscrew standpipe and remove.
c. Remove filter screen and gasket. Wash filter
screen and bowl with solvent (Federal SpeCification
Change 2 12-7