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10-105.
EXTREME WEATHER MAINTENANCE.
10-106.
COLD WEATHER.
Starting in cold weather
will be made easier by the installation of an optional
oil dilution system and a ground power receptacle.
If these aids are not installed, the following proced-
ure may be accomplished.
After the last flight of the day, drain engine oil into
clean containers so it can be preheated.
Cover the
engines, including the rear cowl flap opening, to
prevent ice or snow from collecting inside the cowl-
ing. When preparing an engine for operation after
using this procedure, preheat the oil. After pre-
heating the oil, gasoline may be mixed with the oil
in a ratio of one part gasoline to 12 parts oil before
pouring the oil in the engines. If free air temper-
ature is below -29° C (-20°F), the engine compart-
ments should also be preheated with aground heater.
Check all engine compartment drain and vent lines
for presence of ice. Remove protective covers
placed on engines and rear cowl opening.
Pull
propellers through several revolutions by hand be-
fore starting the engines.
WARNING
Preheat oil before diluting with gasoline, and
do not heat above 121°C (250°F), to prevent
the possibility of a flash fire. Before pulling
propellers through by hand, insure that mag-
neto switches are "OFF."
CAUTION
Due to the desludging effect of the diluted oil,
engine operation should be observed closely
during the initial warm-up of the engines. En-
gines that have a considerable amount of op-
erational hours accumulated since their last
dilution period may be seriously affected by
the dilution process.
This will be caused by
the diluted oil dislodging sludge and carbon
deposits within the engines.
This residue will
collect in the oil sumps and possibly clog the
screened inlet to the oil pumps. Small de-
posits may actually enter the oil pumps and
be trapped by the main oil filter screens.
Partial or, in some cases, complete loss of
engine lubrication may result from either
condition. If these conditions are anticipated
after oil dilution, the engines should be run
for several minutes at normal operating tem-
peratures and then stopped and inspected for
evidence of sludge and carbon deposits in the
oil sumps, oil coolers, and oil filter screens.
Future occurence of this condition can be
prevented by diluting the oil prior to each
oil change.
This will prevent accumulations
of sludge and carbon deposits within the en-
gines.
Winterization kits are available for both engines.
They are essentially devices to restrict the entry of
air through the front cowl opening and to "spoil" air-
flow at the rear cowl flap opening. The kits should
be installed and used in accordance with instructions
accompanying them.
10-107. HOT WEATHER. In hot weather, with a hot
engine, fuel may vaporize at certain points in the fuel
system. Vaporized fuel may be purged by setting the
mixture control in "IDLE CUT-OFF" and operating
the auxiliary fuel pump on "HI."
Engine mis-starts characterized by weak, intermittent
explosions followed by puffs of black smoke from the
exhausts 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, " the mixture control in "IDLE CUT-
OFF, " and the auxiliary fuel pump switch "OFF."
As the engine fires, move the mixture control to full
"RICH" and decrease the throttle to desired idling
speed.
Engine mis-starts characterized by sufficient power
to disengage the starter but dying after 3 to 5 revolu-
tions are the result of an excessively lean mixture
after the start. This can occur in either warm or
cold temperatures.
Repeat the starting routine but
allow additional priming time with the auxiliary fuel
pump switch on "LO" before cranking is started, or
place the auxiliary fuel pump switch on "HI" imme-
diately for a richer mixture while cranking.
If prolonged cranking is necessary, allow the starter
motor to cool at frequent intervals, since excessive
heat may damage the starter.
10-108. DUSTY CONDITIONS.
Dust inducted into
intake systems is probably the greatest single cause
of early engine wear. Under high dust conditions,
the induction air filters should be serviced daily as
outlined in Section 2.
10-109. SEACOAST AND HUMID AREAS. In salt
water areas, special care should be taken to keep
engines and engine accessories clean to prevent
oxidation. Fuel and oil should be checked frequently
and drained of condensed moisture in humid areas.
10-48
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