BEFORE STARTING ENGINES (CONT)
Never connect an external power source to the
aircraft unless a battery indicating a charge of at
least 20 volts is in the aircraft. If the battery volt-
age is less than 20 volts, the battery must be
recharged, or replaced with a battery indicating at
least 20 volts before connecting external power.
Use only an external power source fitted with an
19. GPU - As required.
20. External power advisory light - As
*21. DC volt/loadmeters - Check loads,
voltage, and current limiters.
When an external power source is used, it must be set as fol-
(a) 28.0 to 28.4 volts
(b) 1000 amps capacity
(c) 300 amps maximum continuous
BATT switch should be ON to absorb transients
present in some auxiliary power units. Au EXT
PWR annunciator alerts the crew when an external
power plug is connected to the aircraft.