Cessna 177RG0073, Owner'S Manual

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overheat and evaporate the electrolyte at an excessive rate. In
addition, electronic components in the electrical system could be
adversely affected by the higher than normal voltage if a faulty
voltage regulator setting is causing the overcharging.
To preclude these possibilities, the alternator side of the split
master switch should be turned "OFF." The flight should be
terminated and/or the current drain on the battery minimized as soon
as practical because the battery can supply the electrical system for
only a limited period of time. If it becomes apparent that the battery
voltage is getting too low to operate the electrical system, the
alternator switch can be turned back on for several minutes at a time
until the battery is partially recharged. If the emergency occurs at
night, the alternator switch should be returned to the "ON" position
just before landing lights, landing gear and flaps will be required for
landing.
INSUFFICIENT RATE OF CHARGE.
If the ammeter indicates a continuous discharge rate in flight, the
alternator is not supplying power to the system and should be shut
down since the alternator field circuit may be placing an unnecessary
load on the system. All non-essential equipment should be turned
"OFF" and the flight terminated as soon as practical.
ROUGH ENGINE OPERATION OR LOSS OF
POWER
S P A R K 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 "LEFT" or "RIGHT" 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 normal 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.
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