ELECTRICAL SYSTEMS AND EQUIPMENT
JAR 27.1351 General
(a) Electrical system capacity. Electrical
equipment must be adequate for its intended use.
In addition –
(1) Electric power sources, their
transmission cables, and their associated
control and protective devices must be able to
furnish the required power at the proper
voltage to each load circuit essential for safe
operation; and
(2) Compliance with paragraph (a) (1)
of this paragraph must be shown by an
electrical load analysis, or by electrical
measurements that take into account the
electrical loads applied to the electrical system,
in probable combinations and for probable
durations.
(b) Function. For each electrical system the
following apply:
(1) Each system, when installed, must
be –
(i) Free from hazards in itself, in
its method of operation, and in its effects
on other parts of the rotorcraft; and
(ii) Protected from fuel, oil,
water, other detrimental substances, and
mechanical damage.
(2) Electric power sources must
function properly when connected in
combination or independently.
(3) No failure or malfunction of any
source may impair the ability of any remaining
source to supply load circuits essential for safe
operation.
(4) Each electric power source control
must allow the independent operation of each
source.
(c) Generating system. There must be at
least one generator if the system supplies power to
load circuits essential for safe operation. In
addition –
(1) Each generator must be able to
deliver its continuous rated power;
(2) Generator voltage control
equipment must be able to dependably regulate
each generator output within rated limits;
(3) Each generator must have a reverse
current cut-out designed to disconnect the
generator from the battery and from the other
generators when enough reverse current exists
to damage that generator; and
(4) Each generator must have an over
voltage control designed and installed to
prevent damage to the electrical system, or to
equipment supplied by the electrical system,
that could result if that generator were to
develop an over voltage condition.
(d) Instruments. There must be means to
indicate to appropriate crew members the electric
power system quantities essential for safe
operation of the system. In addition –
(1) For direct current systems, an
ammeter that can be switched into each
generator feeder may be used; and
(2) If there is only one generator, the
ammeter may be in the battery feeder.
(e) External power. If provisions are made
for connecting external power to the rotorcraft,
and that external power can be electrically
connected to equipment other than that used for
engine starting, means must be provided to ensure
that no external power supply having a reverse
polarity, or a reverse phase sequence, can supply
power to the rotorcraft’s electrical system.
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