title-14-part-25-sec25-1435

358

14 CFR Ch. I (1–1–24 Edition)

§ 25.1431

communication between seated flight
attendants.

[Doc. No. 26003, 58 FR 45229, Aug. 26, 1993, as
amended by Amdt. 25–115, 69 FR 40527, July 2,
2004]

ISCELLANEOUS

QUIPMENT

§ 25.1431

Electronic equipment.

(a) In showing compliance with

§ 25.1309 (a) and (b) with respect to
radio and electronic equipment and
their installations, critical environ-
mental conditions must be considered.

(b) Radio and electronic equipment

must be supplied with power under the
requirements of § 25.1355(c).

controls, and wiring must be installed
so that operation of any one unit or
system of units will not adversely af-
fect the simultaneous operation of any
other radio or electronic unit, or sys-
tem of units, required by this chapter.

(d) Electronic equipment must be de-

signed and installed such that it does
not cause essential loads to become in-
operative as a result of electrical
power supply transients or transients
from other causes.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–113, 69 FR 12530, Mar.
16, 2004]

§ 25.1433

Vacuum systems.

There must be means, in addition to

the normal pressure relief, to auto-
matically relieve the pressure in the
discharge lines from the vacuum air
pump when the delivery temperature of
the air becomes unsafe.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–72, 55 FR 29785, July 20,
1990]

§ 25.1435

Hydraulic systems.

(a)

Element design. Each element of

the hydraulic system must be designed
to:

(1) Withstand the proof pressure

without permanent deformation that
would prevent it from performing its
intended functions, and the ultimate
pressure without rupture. The proof
and ultimate pressures are defined in
terms of the design operating pressure
(DOP) as follows:

Element

Proof

(xDOP)

Ultimate

(xDOP)

1. Tubes and fittings. .........................

1.5

3.0

2. Pressure vessels containing gas:

High pressure (e.g., accumula-

tors) .........................................

3.0 4.0

Low pressure (e.g., reservoirs) ..

1.5

3.0

3. Hoses ............................................

2.0

4.0

4. All other elements .........................

1.5

2.0

(2) Withstand, without deformation

that would prevent it from performing
its intended function, the design oper-
ating pressure in combination with
limit structural loads that may be im-
posed;

(3) Withstand, without rupture, the

design operating pressure multiplied by
a factor of 1.5 in combination with ulti-
mate structural load that can reason-
ably occur simultaneously;

(4) Withstand the fatigue effects of

all cyclic pressures, including tran-
sients, and associated externally in-
duced loads, taking into account the
consequences of element failure; and

(5) Perform as intended under all en-

vironmental conditions for which the
airplane is certificated.

(b)

System design. Each hydraulic sys-

tem must:

(1) Have means located at a

flightcrew station to indicate appro-
priate system parameters, if

(i) It performs a function necessary

for continued safe flight and landing;
or

(ii) In the event of hydraulic system

malfunction, corrective action by the
crew to ensure continued safe flight
and landing is necessary;

(2) Have means to ensure that system

pressures, including transient pres-
sures and pressures from fluid volu-
metric changes in elements that are
likely to remain closed long enough for
such changes to occur, are within the
design capabilities of each element,
such that they meet the requirements
defined in § 25.1435(a)(1) through (a)(5);

(3) Have means to minimize the re-

lease of harmful or hazardous con-
centrations of hydraulic fluid or vapors
into the crew and passenger compart-
ments during flight;

(4) Meet the applicable requirements

of §§ 25.863, 25.1183, 25.1185, and 25.1189 if
a flammable hydraulic fluid is used;
and

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§ 25.1439

(5) Be designed to use any suitable

hydraulic fluid specified by the air-
plane manufacturer, which must be
identified by appropriate markings as
required by § 25.1541.

(c)

Tests. Tests must be conducted on

the hydraulic system(s), and/or sub-
system(s) and elements, except that
analysis may be used in place of or to
supplement testing, where the analysis
is shown to be reliable and appropriate.
All internal and external influences
must be taken into account to an ex-
tent necessary to evaluate their ef-
fects, and to assure reliable system and
element functioning and integration.
Failure or unacceptable deficiency of
an element or system must be cor-
rected and be sufficiently retested,
where necessary.

(1) The system(s), subsystem(s), or

element(s) must be subjected to per-
formance, fatigue, and endurance tests
representative of airplane ground and
flight operations.

(2) The complete system must be

tested to determine proper functional
performance and relation to the other
systems, including simulation of rel-
evant failure conditions, and to sup-
port or validate element design.

(3) The complete hydraulic system(s)

must be functionally tested on the air-
plane in normal operation over the
range of motion of all associated user
systems. The test must be conducted at
the system relief pressure or 1.25 times
the DOP if a system pressure relief de-
vice is not part of the system design.
Clearances between hydraulic system
elements and other systems or struc-
tural elements must remain adequate
and there must be no detrimental ef-
fects.

[Doc. No. 28617, 66 FR 27402, May 16, 2001]

§ 25.1438

Pressurization and pneu-

matic systems.

(a) Pressurization system elements

must be burst pressure tested to 2.0
times, and proof pressure tested to 1.5
times, the maximum normal operating
pressure.

(b) Pneumatic system elements must

be burst pressure tested to 3.0 times,
and proof pressure tested to 1.5 times,
the maximum normal operating pres-
sure.

analysis and test, may be substituted
for any test required by paragraph (a)
or (b) of this section if the Adminis-
trator finds it equivalent to the re-
quired test.

[Amdt. 25–41, 42 FR 36971, July 18, 1977]

§ 25.1439

Protective breathing equip-

ment.

(a) Fixed (stationary, or built in) pro-

tective breathing equipment must be
installed for the use of the flightcrew,
and at least one portable protective
breathing equipment shall be located
at or near the flight deck for use by a
flight crewmember. In addition, port-
able protective breathing equipment
must be installed for the use of appro-
priate crewmembers for fighting fires
in compartments accessible in flight
other than the flight deck. This in-
cludes isolated compartments and
upper and lower lobe galleys, in which
crewmember occupancy is permitted
during flight. Equipment must be in-
stalled for the maximum number of
crewmembers expected to be in the
area during any operation.

(b) For protective breathing equip-

ment required by paragraph (a) of this
section or by the applicable Operating
Regulations:

(1) The equipment must be designed

to protect the appropriate crewmember
from smoke, carbon dioxide, and other
harmful gases while on flight deck
duty or while combating fires.

(2) The equipment must include—
(i) Masks covering the eyes, nose and

mouth, or

(ii) Masks covering the nose and

mouth, plus accessory equipment to
cover the eyes.

(3) Equipment, including portable

equipment, must allow communication
with other crewmembers while in use.
Equipment available at flightcrew as-
signed duty stations must also enable
the flightcrew to use radio equipment.

(4) The part of the equipment pro-

tecting the eyes shall not cause any ap-
preciable adverse effect on vision and
must allow corrective glasses to be
worn.

(5) The equipment must supply pro-

tective oxygen of 15 minutes duration
per crewmember at a pressure altitude
of 8,000 feet with a respiratory minute