CESSNA
SECTION 4
MODEL 172RG
NORMAL PROCEDURES
AMPLIFIED PROCEDURES
STARTING ENGINE
Ordinarily the engine starts easily with one or two pumps of the
throttle in warm temperatures with the mixture full rich. If the engine is
hot, turn the auxiliary fuel pump switch ON just prior to and during engine
cranking to suppress possible vapor in the fuel line. Turn the auxiliary
fuel pump switch OFF after the engine starts. In cooler weather, use of the
primer will facilitate engine starting.
NOTE
Additional details concerning cold weather starting and
operation may be found under COLD WEATHER OPERA-
TION paragraphs in this section.
Weak intermittent firing followed by puffs of black smoke from the
exhaust stack indicates overpriming or flooding. Excess fuel can be
cleared from the combustion chambers by the following procedure: Set the
mixture control full lean and the throttle full open; then crank the engine
through several revolutions with the starter. Repeat the starting proce-
dure without any additional priming.
If the engine is underprimed (most likely in cold weather with a cold
engine) it will not fire at all. Additional priming will be necessary for the
next starting attempt.
If prolonged cranking is necessary, allow the starter motor to cool at
frequent intervals, since excessive heat may damage the armature.
After starting, if the oil gage does not begin to show pressure within 30
seconds in the summertime and about twice that long in very cold weather,
stop engine and investigate. Lack of oil pressure can cause serious engine
damage. After starting, avoid the use of carburetor heat unless icing
conditions prevail.
TAXIING
When taxiing, it is important that speed and use of brakes be held to a
minimum and that all controls be utilized (see Taxiing Diagram, figure 4-
2) to maintain directional control and balance.
The carburetor heat control knob should be pushed full in during all
ground operations unless heat is absolutely necessary for smooth engine
1 July 1979
4-13
