battery is connected to the battery bus and
battery charging bus. Individual battery volt-
age may be read by turning on the respective
battery switch if no other power source is con-
nected to the battery charging bus.
NOTE
The batteries are connected in par-
allel, including engine starts, only
when both battery switches are on.
Emergency Operation—
Airplane Batteries Only
See Section III of the appropriate AFM.
OPTIONAL EMERGENCY
BATTERY SYSTEM
One or two emergency batteries may be in-
stalled in the airplane in either the tailcone or
nose section. The batteries are dry cell nicad
and are rated at 25 VDC. A switch and an
amber light are provided with each battery. A
100-VA inverter powered by the battery sup-
plies 115-VAC, 400-Hz, single-phase power
for the standby attitude indicator and emer-
gency directional gyro, if installed. The bat-
tery receives a trickle-charge from the main
DC bus. The emergency battery or batteries
may operate the following equipment:
• Emergency attitude gyro
• Gear
• Flaps
• Spoilers
• Emergency directional gyro
• Emergency communications radio
Operation—Airplanes Equipped
with a Single Emergency
Battery
The system is controlled by a single ON–OFF
switch or, on 25-209 and subsequent, by an
ON–OFF–STBY emergency power switch.
Both switch installations (Figure 2-4) are lo-
cated on the pilot’s instrument panel. If air-
plane power is lost, the emergency battery
provides DC, 115-VAC, and 4.6-VAC power
through a self-contained inverter. The emer-
gency attitude indicator is powered and illu-
minated with AC power and the emergency
battery indicator light, and the gear, flaps and
spoilers are powered with DC power. Some air-
planes have an emergency communications
radio wired to the emergency battery. Airplanes
with a two-position switch may or may not
power the gear, flaps, and spoilers.
Airplanes Equipped with Dual
Emergency Batteries
The dual battery system is controlled with an
ON–OFF and an ON–OFF–STBY emergency
power switch. When airplane electrical power
is lost, the two-position switch provides power
to its associated avionics and emergency bat-
tery indicator light. The three-position switch
provides power to its associated circuits, nor-
mally the gear, flaps and spoiler systems, the
emergency attitude indicator and light, and
the emergency battery indicator light. The
STBY position is used to conserve battery
power when the expected flight time exceeds
30 minutes by removing power to the gear,
flaps, and spoilers.
With either a dual or single emergency battery
system, the battery indicator lights illuminate
only when the emergency battery is providing
power. In this case, the spoiler light and flap
indicator are inoperative but the gear indica-
tor lights still function.
2-4
FOR TRAINING PURPOSES ONLY
LEARJET 20 SERIES PILOT TRAINING MANUAL
FlightSafety
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