Electrical Failures; Electrical Overload - Piper ARCHER III Pilot Operating Handbook

SECTION 3
EMERGENCY PROCEDURES

3.25 ELECTRICAL FAILURES

Anytime the bus voltage is below 25 Vdc, the Low
Bus Voltage Annunciator will be illuminated.
Loss of alternator output is detected through zero reading on the
ammeter. Before executing the following procedure, insure that the reading
is zero and not merely low by actuating an electrically powered device, such
as the landing light. If no increase in the ammeter reading is noted, alternator
failure can be assumed.
The electrical load should be reduced as much as possible. Check the
alternator circuit breakers for a popped circuit.
The next step is to attempt to reset the overvoltage relay. This is
accomplished by moving the ALT switch to OFF for one second and then to
ON. If the trouble was caused by a momentary overvoltage condition (30.5
volts and up) this procedure should return the ammeter to a normal reading.
Low Bus Voltage Annunciator will be illuminated.
If the ammeter continues to indicate ``0'' output, or if the alternator will
not remain reset, turn off the ALT switch, maintain minimum electrical load
and land as soon as practical. Anticipate complete electrical failure. Duration
of battery power will be dependent on electrical load and battery condition
prior to failure.
3.27 ELECTRICAL OVERLOAD (Alternator over 20 amps above known
electrical load)
If abnormally high alternator output is observed (more than 20 amps
above known electrical load for the operating conditions) it may be caused
by a low battery, a battery fault or other abnormal electrical load. If the
cause is a low battery, the indication should begin to decrease toward normal
within 5 minutes. If the overload condition persists attempt to reduce the
load by turning off non-essential equipment.
REPORT: VB-1611
3-14
PA-28-181, ARCHER III
NOTE:
NOTE:
ISSUED: JULY 12, 1995