358 

14 CFR Ch. I (1–1–19 Edition) 

§ 25.1438 

(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. 

(c) An analysis, or a combination of 

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 
volume of 30 liters per minute BTPD. 
The equipment and system must be de-
signed to prevent any inward leakage 
to the inside of the device and prevent 

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