315 

Federal Aviation Administration, DOT 

§ 23.1441 

(1) Each hydraulic system and its ele-

ments must withstand, without yield-
ing, the structural loads expected in 
addition to hydraulic loads. 

(2) A means to indicate the pressure 

in each hydraulic system which sup-
plies two or more primary functions 
must be provided to the flight crew. 

(3) There must be means to ensure 

that the pressure, including transient 
(surge) pressure, in any part of the sys-
tem will not exceed the safe limit 
above design operating pressure and to 
prevent excessive pressure resulting 
from fluid volumetric changes in all 
lines which are likely to remain closed 
long enough for such changes to occur. 

(4) The minimum design burst pres-

sure must be 2.5 times the operating 
pressure. 

(b) 

Tests.  Each system must be sub-

stantiated by proof pressure tests. 
When proof tested, no part of any sys-
tem may fail, malfunction, or experi-
ence a permanent set. The proof load of 
each system must be at least 1.5 times 
the maximum operating pressure of 
that system. 

(c) 

Accumulators.  A hydraulic accu-

mulator or reservoir may be installed 
on the engine side of any firewall if— 

(1) It is an integral part of an engine 

or propeller system, or 

(2) The reservoir is nonpressurized 

and the total capacity of all such non-
pressurized reservoirs is one quart or 
less. 

[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as 
amended by Amdt. 23–7, 34 FR 13096, Aug. 13, 
1969; Amdt. 23–14, 38 FR 31824, Nov. 19, 1973; 
Amdt. 23–43, 58 FR 18977, Apr. 9, 1993; Amdt. 
23–49, 61 FR 5170, Feb. 9, 1996] 

§ 23.1437

Accessories for multiengine 

airplanes. 

For multiengine airplanes, engine- 

driven accessories essential to safe op-
eration must be distributed among two 
or more engines so that the failure of 
any one engine will not impair safe op-
eration through the malfunctioning of 
these accessories. 

§ 23.1438

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. 23–20, 42 FR 36969, July 18, 1977] 

§ 23.1441

Oxygen equipment and sup-

ply. 

(a) If certification with supplemental 

oxygen equipment is requested, or the 
airplane is approved for operations at 
or above altitudes where oxygen is re-
quired to be used by the operating 
rules, oxygen equipment must be pro-
vided that meets the requirements of 
this section and §§ 23.1443 through 
23.1449. Portable oxygen equipment 
may be used to meet the requirements 
of this part if the portable equipment 
is shown to comply with the applicable 
requirements, is identified in the air-
plane type design, and its stowage pro-
visions are found to be in compliance 
with the requirements of § 23.561. 

(b) The oxygen system must be free 

from hazards in itself, in its method of 
operation, and its effect upon other 
components. 

(c) There must be a means to allow 

the crew to readily determine, during 
the flight, the quantity of oxygen 
available in each source of supply. 

(d) Each required flight crewmember 

must be provided with— 

(1) Demand oxygen equipment if the 

airplane is to be certificated for oper-
ation above 25,000 feet. 

(2) Pressure demand oxygen equip-

ment if the airplane is to be certifi-
cated for operation above 40,000 feet. 

(e) There must be a means, readily 

available to the crew in flight, to turn 
on and to shut off the oxygen supply at 
the high pressure source. This shutoff 
requirement does not apply to chem-
ical oxygen generators. 

[Amdt. 23–9, 35 FR 6386, Apr. 21, 1970, as 
amended by Amdt. 23–43, 58 FR 18978, Apr. 9, 
1993] 

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