Cessna 150K - Ground Service Receptacle; Hot Weather; Dusty Conditions; Seacoast and Humid Areas

10
primer. Operating the primer plunger in the cabin
forces fuel to the engine. Fuel is delivered to the
intake manifold above the carburetor, therefore,
priming the intake manifold. Crushed or broken
primer lines should be replaced with new parts.
Primer lines should be properly clamped to prevent
vibration and chafing. With the ground service re-
ceptacle installed, an external power source may be
connected to assist in cold weather or low battery
starting. Refer to paragraph 11-66 for use of the
ground service receptacle.
The following may also be used to assist engine
starting in extreme cold weather. After the last
flight of the day, drain the engine oil into a clean
container so the oil can be preheated. Cover the
engine to prevent ice or snow from collecting inside
the cowling. When preparing the aircraft for flight
or engine run-up after these conditions have been
followed, preheat the drained oil.
IWARNING'
Do not heat oil above 121°C (250°F). A flash
fire may result. Before pulling the propeller
through, ascertain that magneto switch is in
OFF position to prevent the engine from firing.
After preheating the oil, gasoline may be mixed with
the heated oil in a ratio of 1 part gasoline to 12 parts
oil before pouring into the engine oil sump. If the
free air temperature is belbw -29°C (-20°F), the
engine compartment should be preheated with a
ground heater. After the engine compartment has
been preheated, inspect all engine drain and vent
lines for presence of ice. After this procedure has
been complied with, pull propeller through several
revolutions by hand before starting the engine.
Due to the desludging effect of the diluted oil,
engine operation should be observed closely
during the initial warm-up of the engine. En-
gines that have a considerable amount of opera-
tional hours accumulated since their last dilu-
tion period may be seriously affected by the
dilution process. This is caused by the diluted
oil dislodging sludge and carbon deposits within
the engine. This residue will collect in the oil
sump and possibly clog the screened inlet to
the oil pump. Small deposits may actually enter
the oil pump and be trapped by the pressure
oil filter screen. Partial or, in some cases,
complete loss of engine lubrication may re-
sult from either condition. If these conditions
are antiCipated after oil dilution, the engine
should be operated for several minutes at
normal operating temperatures and then stop-
ped and inspected for evidence of sludge and
carbon deposits in the oil sump and oil filter
screen. Future occurrence of this condition
can be prevented by diluting the oil prior to
each oil change. This will prevent the build-
up accumulation of the sludge and carbon de-
posits within the engine.
11-66. GROUND SERVICE RECEPTACLE. With the
ground service receptacle installed, the use of an
external power source is recommended for cold
weather and low battery starting and lengthy main-
tenance work on the aircraft electrical systems.
The battery and external power circuits have been
designed to completely eliminate the need to "jumper"
across the battery contactors to close it. A special
fused circuit in the external power system supplies
the needed "jumper" across the contacts so that with
a "dead" battery and an external power source ap-
plied, turning the master switch ON will close the
battery contactor.
ICAUTION\
Be certain that the polarity of any external
power source is correct (positive to positive
and negative to negative). A polarity rever-
sal will result in immediate damage to the
electrical and electronic circuits of the air-
craft.
11-67. HOT WEATHER. Engine mis-starts char-
acterized by weak, intermittent explosions followed
by puffs of black smoke from the exhaust are caused
by over-priming or flooding. This situation is more
apt to develop in hot weather or when the engine is
hot. If it occurs, repeat the starting routine with
the throttle approximately one-half OPEN, and the
mixture control in IDLE CUT-OFF. As the engine
fires, move the mixture control to full RICH and
decrease the throttle setting to desired idling speed.
Engine mis-starts characterized by sufficient power
to disengage the starter but dying after three to five
revolutions are the result of an excessively lean
mixture after the start. This can occur either in
warm or cold temperatures. Repeat the starting
routine with additional priming.
ICAUTION\
Never operate the starting motor more than
12 seconds at a time. Allow starter motor
to cool between cranking periods to avoid
overheating. Longer cranking periods will
shorten the life of the starter.
11-68. DUSTY CONDITIONS. Dust inducted into the
intake system of the engine is probably the greatest
single cause of early engine wear. When operating
under high dust conditions, the induction air filter
should be serviced daily as outlined in paragraph
2-17.
11-69. SEACOAST AND HUMID AREAS. In salt
water areas, special care should be taken to keep
the engine and accessories clean to prevent oxida-
tion. In humid areas, fuel and oil should be checked
frequently and drained of condensed moisture.
11-70. HAND CRANKING. A normal hand-cranking
procedure may be used to start the engine.
11-25/(11-26 blank)