TM 55-1510-219-10
Figure 2-26. Overhead Circuit Breaker Panel
d.
Volt-Loadmeters. Two meters (fig. 2-18), on
the overhead control panel display voltage readings and
show the rate of current usage from left and right
generating systems. Each meter is equipped with a
spring-loaded push-button switch which when manually
pressed will cause the meter to indicate main bus
voltage. Each meter normally shows output amperage
reading from the respective generator, unless the push-
button switch is pressed to obtain bus voltage reading.
Current consumption is indicated as a percentage of
total output amperage capacity for the generating
system monitored.
e.
Battery
Monitor.
Nickel-cadmium
battery
overheating will cause the battery charge current to
increase if thermal runaway is imminent. The aircraft
has a charge-current sensor which will detect a charge
current. The charge current system senses battery
current through a shunt in the negative lead of the
battery. Any time the battery charging current exceeds
approximately 7-amperes for 6 seconds or longer, the
yellow BATTERY CHARGE annunciator light and the
master fault caution light will illuminate. Following a
battery engine start, the caution light will illuminate
approximately six seconds after the generator switch is
placed in the ON position. The light will normally
extinguish within two to five minutes, indicating that the
battery is approaching a full charge. The time interval
will increase if the battery has a low state of charge, the
battery temperature is very low, or if the battery has
previously been discharged at a very low rate (i.e.,
battery operation of radios or lights for prolonged
periods). The caution light may also illuminate for short
intervals after landing gear and/or flap operation. If the
caution light should illuminate during normal steady-
state cruise, it indicates that conditions exist that may
cause a battery thermal runaway. If this occurs, the
battery switch shall be turned OFF and may be turned
back ON only for gear and flap extension and approach
to landing. Battery may be used after a 15 to 20 minute
cool down period.
f.
Generator
Out
Warning
Lights.
Two
caution/advisory annunciator panel lights inform the pilot
when either generator is not delivering current to the
aircraft DC bus system. These lights are placarded #1
DC GEN and #2 DC GEN. Two MASTER CAUTION
lights and illumination of either fault light indicates that
either the identified generator has failed or voltage is not
sufficient to keep it connected to the power distribution
system.
2-65
