Section 25.1705

14 CFR Ch. I (1-1-19 Edition)

(3) Perform the function for which it
was intended without degrading the
airworthiness of the airplane.
(4) Be designed and installed in a way
that will minimize mechanical strain.
(b) Selection of wires must take into
account known characteristics of the
wire in relation to each installation
and application to minimize the risk of
wire damage, including any arc tracking phenomena.
(c) The design and installation of the
main power cables (including generator
cables) in the fuselage must allow for a
reasonable degree of deformation and
stretching without failure.
(d) EWIS components located in
areas of known moisture accumulation
must be protected to minimize any
hazardous effects due to moisture.

spaschal on DSK3GDR082PROD with CFR

Section 25.1705

Systems and functions: EWIS.

(a) EWIS associated with any system
required for type certification or by operating rules must be considered an integral part of that system and must be
considered in showing compliance with
the applicable requirements for that
system.
(b) For systems to which the following rules apply, the components of
EWIS associated with those systems
must be considered an integral part of
that system or systems and must be
considered in showing compliance with
the applicable requirements for that
system.
(1) Section 25.773(b)(2) Pilot compartment
view.
(2) Section 25.981 Fuel tank ignition prevention.
(3) Section 25.1165 Engine ignition systems.
(4) Section 25.1310 Power source capacity
and distribution.
(5) Section 25.1316 System lightning protection.
(6) Section 25.1331(a)(2) Instruments using a
power supply.
(7) Section 25.1351 General.
(8) Section 25.1355 Distribution system.
(9) Section 25.1360 Precautions against injury.
(10) Section 25.1362 Electrical supplies for
emergency conditions.
(11) Section 25.1365 Electrical appliances,
motors, and transformers.
(12) Section 25.1431(c) and (d) Electronic
equipment.

Section 25.1707

System separation: EWIS.

(a) Each EWIS must be designed and
installed with adequate physical separation from other EWIS and airplane
systems so that an EWIS component
failure will not create a hazardous condition. Unless otherwise stated, for the
purposes of this section, adequate
physical separation must be achieved
by separation distance or by a barrier
that provides protection equivalent to
that separation distance.
(b) Each EWIS must be designed and
installed so that any electrical interference likely to be present in the airplane will not result in hazardous effects upon the airplane or its systems.
(c) Wires and cables carrying heavy
current, and their associated EWIS
components, must be designed and installed to ensure adequate physical
separation and electrical isolation so
that damage to circuits associated
with essential functions will be minimized under fault conditions.
(d) Each EWIS associated with independent airplane power sources or
power sources connected in combination must be designed and installed to
ensure adequate physical separation
and electrical isolation so that a fault
in any one airplane power source EWIS
will not adversely affect any other
independent power sources. In addition:
(1) Airplane independent electrical
power sources must not share a common ground terminating location.
(2) Airplane system static grounds
must not share a common ground terminating location with any of the airplane-s independent electrical power
sources.
(e) Except to the extent necessary to
provide electrical connection to the
fuel systems components, the EWIS
must be designed and installed with
adequate physical separation from fuel
lines and other fuel system components, so that:
(1) An EWIS component failure will
not create a hazardous condition.
(2) Any fuel leakage onto EWIS components will not create a hazardous
condition.
(f) Except to the extent necessary to
provide electrical connection to the
hydraulic systems components, EWIS
must be designed and installed with

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