EAA Sport Aviation

the wires can safely carry, these devices shut
off the flow of current to prevent damage.
The difference between the two is that
circuit breakers can be reset, but fuses must
be replaced once they “blow.”
The important thing to remember is that
circuit breakers don’t trip without reason. A
popped breaker or blown fuse is an
indication that the electrical circuit has been
overloaded. The general rule is that a circuit
breaker can be reset one time if it trips off. If
it trips again after being reset, it should be
left alone until the system can be inspected
and repaired. Similarly, a fuse can be
replaced once, but if it then blows again,
there is trouble. Never wrap a fuse with
conductive material or replace it with a fuse
of higher amperage, as this may allow too
much current to pass through the wires.
This can result in overheated wires, heat-
damaged insulation, and an electrical fire.

CHARGING SYSTEM FAILURE
Perhaps a more distressing problem for a
pilot in flight is the complete failure of the
aircraft’s charging system. When an
alternator or generator fails or can’t produce
sufficient power, the battery will carry the
load for a limited period of time. That time
depends on the condition of the battery and
the electrical load placed upon it. The first
thing to do is reduce the electrical load by
turning off unnecessary electrical
components (referred to as “load
shedding”). The idea is to reduce the load on
the battery as much as practical and
conserve electrical power to meet critical
needs, such as required radio calls and
extending gear and flaps for landing.
Markings on the circuit breakers indicate
the relative current draw for each circuit
and can guide us in our load-shedding
process. Just remember, too, that an amp
here and an amp there will quickly add up to
a significant drain on the battery.

Robert N. Rossier, EAA 472091, has been flying for more than 30 years and has worked as a flight instructor, commercial pilot, chief pilot, and FAA flight check airman.