12.1.1 Electrical installationsfootnote shall be such that:
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.1 all electrical auxiliary services necessary
for maintaining the craft in normal operation and habitable conditions
will be ensured without recourse to the emergency source of electrical
power;
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.2 electrical services essential for safety will
be ensured under various emergency conditions; and
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.3 the safety of passengers, crew and craft from
electrical hazards will be ensured.
The FMEA shall include the electrical system, taking into account
the effects of electrical failure on the systems being supplied. In
cases where faults can occur without being detected during routine
checks on the installations, the analysis shall take into account
the possibility of faults occurring simultaneously or consecutively.
12.1.2 The electrical system shall be designed
and installed so that the probability of the craft being at risk of
failure of a service is extremely remote.
12.1.3 Where loss of particular essential service
would cause serious risk to the craft, the service shall be fed by
at least two independent circuits fed in such a way that no single
failure in the electrical supply or distribution systems would affect
both supplies.
12.1.4 The securing arrangements for heavy items,
i.e. accumulator batteries, shall, as far as practicable, prevent
excessive movement during the accelerations due to grounding or collision.
12.1.5 Precautions shall be taken to minimise
risk of supplies to essential and emergency services being interrupted
by the inadvertent or accidental opening of switches or circuit-breakers.