Cessna 17273274, Руководство по эксплуатации для пилотов

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SECTION 3
EMERGENCY PROCEDURES
CESSNA
MODEL 172N
ROUGH ENGINE OPERATION OR LOSS OF
POWER
CARBURETOR ICING
A gradual loss of RPM and eventual engine roughness may result from
the formation of carburetor ice. To clear the ice, apply full throttle and pull
the carburetor heat knob full out until the engine runs smoothly; then
remove carburetor heat and readjust the throttle.
If
conditions require the
continued use of carburetor heat in cruise flight, use the minimum amount
of heat necessary to prevent ice from forming and lean t}:le mixture for
smoothest engine operation.
SPARK PLUG FOULING
A slight engine roughness in flight may be caused by one or more
spark plugs becoming fouled by carbon or lead deposits. This may be
verified by turning the ignition switch momentarily from BOTH to either L
or R position. An obvious power loss in single ignition operation is
evidence of spark plug or magneto trouble. Assuming that spark plugs are
the more likely cause, lean the mixture to the recommended lean setting for
cruising flight.
If
the problem does not clear up in several minutes,
determine if a richer mixture setting will produce smoother operation.
If
not, proceed to the nearest airport for repairs using the BOTH position of
the ignition switch unless extreme roughness dictates the use of a single
ignition position.
MAGNETO MALFUNCTION
A sudden engine roughness or misfiring is usually evidence of
magneto problems. Switching from BOTH to either Lor R ignition switch
position will identify which magneto is malfunctioning. Select different
power settings and enrichen the mixture to determine if continued opera­
tion on BOTH magnetos is practicable.
If
not, switch to the good magneto
and proceed to the nearest airport for repairs.
LOW OIL PRESSURE
If
low oil pressure is accompanied by normal oil temperature, there is
a possibility the oil pressure gage or relief valve is malfunctioning. A leak
in the line to the gage is not necessarily cause for an immediate precau­
tionary landing because an orifice in this line will prevent a sudden loss of
oil from the engine sump. However, a landing at the nearest airport would
be advisable to inspect the source of trouble.
If
a total loss of oil pressure is accompanied by a rise in oil tempera­
ture, there is good reason to suspect an engine failure is imminent. Reduce
3-16
1 July 1979