Cessna 182T 2001, Pilot Operating Handbook

Page: 78 / 254

SECTION 3 - EMERGENCY PROCEDURES CESSNA
FAA APPROVED MODEL 182T
ELECTRICAL POWER SUPPLY
SYSTEM MALFUNCTIONS
Malfunctions in the electrical power supply system can be
detected by periodic monitoring of the ammeter and low voltage
annunciator (VOLTS); however, the cause of these malfunctions is
usually difficult to determine. A broken alternator drive belt or wiring
is most likely the cause of alternator failures, although other factors
could cause the problem. A defective alternator control unit can also
cause malfunctions. Problems of this nature constitute an electrical
emergency and should be dealt with immediately. Electrical power
malfunctions usually fall into two categories: excessive rate of
charge and insufficient rate of charge. The following paragraphs
describe the recommended remedy for each situation.
EXCESSIVE RATE OF CHARGE
After engine starting and heavy electrical usage at low engine
speeds (such as extended taxiing) the battery condition will be low
enough to accept above normal charging during the initial part of a
flight. However, after thirty minutes of cruising flight, the ammeter
should be indicating less than two needle widths of charging
current. If the charging rate were to remain above this value on a
long flight, the battery would overheat and evaporate the electrolyte
at an excessive rate.
Electronic components in the electrical system can be adversely
affected by higher than normal voltage. The alternator control unit
includes an overvoltage sensor which normally will automatically
shut down the alternator if the charge voltage reaches
approximately 31.5 volts. If the overvoltage sensor malfunctions, as
evidenced by an excessive rate of charge shown on the ammeter,
the alternator should be turned off, nonessential electrical
equipment turned off and the flight terminated as soon as practical.
3-22 Feb 23/01