title-14-part-29-sec29-1351

661

Federal Aviation Administration, DOT

§ 29.1351

(2) When two or more tanks are close-

ly interconnected by a gravity feed sys-
tem and vented, and when it is impos-
sible to feed from each tank sepa-
rately, at least one fuel quantity indi-
cator must be installed;

(3) Tanks with interconnected outlets

and airspaces may be treated as one
tank and need not have separate indi-
cators; and

(4) Each exposed sight gauge used as

a fuel quantity indicator must be pro-
tected against damage.

(c)

Fuel flowmeter system. If a fuel

flowmeter system is installed, each
metering component must have a
means for bypassing the fuel supply if
malfunction of that component se-
verely restricts fuel flow.

(d)

Oil quantity indicator. There must

be a stick gauge or equivalent means
to indicate the quantity of oil—

(1) In each tank; and
(2) In each transmission gearbox.
(e) Rotor drive system transmissions

and gearboxes utilizing ferromagnetic
materials must be equipped with chip
detectors designed to indicate the pres-
ence of ferromagnetic particles result-
ing from damage or excessive wear
within the transmission or gearbox.
Each chip detector must—

(1) Be designed to provide a signal to

the indicator required by
§ 29.1305(a)(22); and

(2) Be provided with a means to allow

crewmembers to check, in flight, the
function of each detector electrical cir-
cuit and signal.

(Secs. 313(a), 601, and 603, 72 Stat. 759, 775, 49
U.S.C. 1354(a), 1421, and 1423; sec. 6(c), 49
U.S.C. 1655(c))

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–13, 42 FR 15047, Mar. 17,
1977; Amdt. 29–26, 53 FR 34219, Sept. 2, 1988]

LECTRICAL

YSTEMS AND

QUIPMENT

§ 29.1351

General.

(a)

Electrical system capacity. The re-

quired generating capacity and the
number and kind of power sources
must—

(1) Be determined by an electrical

load analysis; and

(2) Meet the requirements of § 29.1309.
(b)

Generating system. The generating

system includes electrical power
sources, main power busses, trans-

mission cables, and associated control,
regulation, and protective devices. It
must be designed so that—

(1) Power sources function properly

when independent and when connected
in combination;

(2) No failure or malfunction of any

power source can create a hazard or
impair the ability of remaining sources
to supply essential loads;

(3) The system voltage and frequency

(as applicable) at the terminals of es-
sential load equipment can be main-
tained within the limits for which the
equipment is designed, during any
probable operating condition;

(4) System transients due to switch-

ing, fault clearing, or other causes do
not make essential loads inoperative,
and do not cause a smoke or fire haz-
ard;

(5) There are means accessible in

flight to appropriate crewmembers for
the individual and collective dis-
connection of the electrical power
sources from the main bus; and

(6) There are means to indicate to ap-

propriate crewmembers the generating
system quantities essential for the safe
operation of the system, such as the
voltage and current supplied by each
generator.

(c)

External power. If provisions are

made for connecting external power to
the rotorcraft, and that external power
can be electrically connected to equip-
ment 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.

(d) Operation with the normal elec-

trical power generating system inoper-
ative.

(1) It must be shown by analysis,

tests, or both, that the rotorcraft can
be operated safely in VFR conditions
for a period of not less than 5 minutes,
with the normal electrical power gen-
erating system (electrical power
sources excluding the battery) inoper-
ative, with critical type fuel (from the
standpoint of flameout and restart ca-
pability), and with the rotorcraft ini-
tially at the maximum certificated al-
titude. Parts of the electrical system
may remain on if—

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662

14 CFR Ch. I (1–1–24 Edition)

§ 29.1353

(i) A single malfunction, including a

wire bundle or junction box fire, can-
not result in loss of the part turned off
and the part turned on;

(ii) The parts turned on are elec-

trically and mechanically isolated
from the parts turned off; and

(2) Additional requirements for Cat-

egory A Rotorcraft.

(i) Unless it can be shown that the

loss of the normal electrical power gen-
erating system is extremely improb-
able, an emergency electrical power
system, independent of the normal
electrical power generating system,
must be provided, with sufficient ca-
pacity to power all systems necessary
for continued safe flight and landing.

(ii) Failures, including junction box,

control panel, or wire bundle fires,
which would result in the loss of the
normal and emergency systems, must
be shown to be extremely improbable.

(iii) Systems necessary for imme-

diate safety must continue to operate
following the loss of the normal elec-
trical power generating system, with-
out the need for flight crew action.

(e) Electrical equipment, controls,

and wiring must be installed so that
operation of any one unit or system of
units will not adversely affect the si-
multaneous operation of any other
electrical unit or system essential to
safe operation.

(f) Cables must be grouped, routed,

and spaced so that damage to essential
circuits will be minimized if there are
faults in heavy current-carrying ca-
bles.

(Secs. 313(a), 601, 603, 604, and 605 of the Fed-
eral Aviation Act of 1958 (49 U.S.C. 1354(a),
1421, 1423, 1424, and 1425); and sec. 6(c), Dept.
of Transportation Act (49 U.S.C. 1655(c)))

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–14, 42 FR 36973, July 18,
1977; Amdt. 29–40, 61 FR 21908, May 10, 1996;
Amdt. 29–42, 63 FR 43285, Aug. 12, 1998; Amdt.
29–59, 88 FR 8740, Feb. 10, 2023]

§ 29.1353

Energy storage systems.

Energy storage systems must be de-

signed and installed as follows:

(a) Energy storage systems must pro-

vide automatic protective features for
any conditions that could prevent con-
tinued safe flight and landing.

(b) Energy storage systems must not

emit any flammable, explosive, or

toxic gases, smoke, or fluids that could
accumulate in hazardous quantities
within the rotorcraft.

cape from the system must not damage
surrounding structures, adjacent equip-
ment, or systems necessary for contin-
ued safe flight and landing.

(d) The maximum amount of heat

and pressure that can be generated dur-
ing any operation or under any failure
condition of the energy storage system
or its individual components must not
result in any hazardous effect on rotor-
craft structure, equipment, or systems
necessary for continued safe flight and
landing.

(e) Energy storage system installa-

tions required for continued safe flight
and landing of the rotorcraft must
have monitoring features and a means
to indicate to the pilot the status of all
critical system parameters.

[Amdt. 29–59, 88 FR 8740, Feb. 10, 2023]

§ 29.1355

Distribution system.

(a) The distribution system includes

the distribution busses, their associ-
ated feeders, and each control and pro-
tective device.

(b) If two independent sources of

electrical power for particular equip-
ment or systems are required by this
chapter, in the event of the failure of
one power source for such equipment or
system, another power source (includ-
ing its separate feeder) must be pro-
vided automatically or be manually se-
lectable to maintain equipment or sys-
tem operation.

(Secs. 313(a), 601, 603, 604, and 605 of the Fed-
eral Aviation Act of 1958 (49 U.S.C. 1354(a),
1421, 1423, 1424, and 1425); and sec. 6(c), Dept.
of Transportation Act (49 U.S.C. 1655(c)))

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–14, 42 FR 36973, July 18,
1977; Amdt. 29–24, 49 FR 44439, Nov. 6, 1984]

§ 29.1357

Circuit protective devices.

(a) Automatic protective devices

must be used to minimize distress to
the electrical system and hazard to the
rotorcraft system and hazard to the
rotorcraft in the event of wiring faults
or serious malfunction of the system or
connected equipment.

(b) The protective and control de-

vices in the generating system must be