Code of Federal Regulations - Title 14

473

Federal Aviation Administration, DOT

§ 25.955

the tank capacity. It must be impos-
sible to fill the expansion space inad-
vertently with the airplane in the nor-
mal ground attitude.

must be designed and located in ac-
cordance with § 25.1455 if—

(1) The augmentation system fluid is

subject to freezing; and

(2) The fluid may be drained in flight

or during ground operation.

(d) The augmentation liquid tank ca-

pacity available for the use of each en-
gine must be large enough to allow op-
eration of the airplane under the ap-
proved procedures for the use of liquid-
augmented power. The computation of
liquid consumption must be based on
the maximum approved rate appro-
priate for the desired engine output
and must include the effect of tempera-
ture on engine performance as well as
any other factors that might vary the
amount of liquid required.

(e) This section does not apply to fuel

injection systems.

[Amdt. 25–40, 42 FR 15043, Mar. 17, 1977, as
amended by Amdt. 25–72, 55 FR 29785, July 20,
1990; Amdt. 25–115, 69 FR 40527, July 2, 2004]

UEL

YSTEM

§ 25.951

General.

(a) Each fuel system must be con-

structed and arranged to ensure a flow
of fuel at a rate and pressure estab-
lished for proper engine and auxiliary
power unit functioning under each
likely operating condition, including
any maneuver for which certification is
requested and during which the engine
or auxiliary power unit is permitted to
be in operation.

(b) Each fuel system must be ar-

ranged so that any air which is intro-
duced into the system will not result
in—

(1) Power interruption for more than

20 seconds for reciprocating engines; or

(2) Flameout for turbine engines.
(c) Each fuel system for a turbine en-

gine must be capable of sustained oper-
ation throughout its flow and pressure
range with fuel initially saturated with
water at 80

F and having 0.75cc of free

water per gallon added and cooled to
the most critical condition for icing
likely to be encountered in operation.

(d) Each fuel system for a turbine en-

gine powered airplane must meet the
applicable fuel venting requirements of
part 34 of this chapter.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–23, 35 FR 5677, Apr. 8,
1970; Amdt. 25–36, 39 FR 35460, Oct. 1, 1974;
Amdt. 25–38, 41 FR 55467, Dec. 20, 1976; Amdt.
25–73, 55 FR 32861, Aug. 10, 1990]

§ 25.952

Fuel system analysis and test.

(a) Proper fuel system functioning

under all probable operating conditions
must be shown by analysis and those
tests found necessary by the Adminis-
trator. Tests, if required, must be made
using the airplane fuel system or a test
article that reproduces the operating
characteristics of the portion of the
fuel system to be tested.

(b) The likely failure of any heat ex-

changer using fuel as one of its fluids
may not result in a hazardous condi-
tion.

[Amdt. 25–40, 42 FR 15043, Mar. 17, 1977]

§ 25.953

Fuel system independence.

Each fuel system must meet the re-

quirements of § 25.903(b) by—

(a) Allowing the supply of fuel to

each engine through a system inde-
pendent of each part of the system sup-
plying fuel to any other engine; or

(b) Any other acceptable method.

§ 25.954

Fuel system lightning protec-

tion.

The fuel system must be designed

and arranged to prevent the ignition of
fuel vapor within the system by—

(a) Direct lightning strikes to areas

having a high probability of stroke at-
tachment;

(b) Swept lightning strokes to areas

where swept strokes are highly prob-
able; and

vent outlets.

[Amdt. 25–14, 32 FR 11629, Aug. 11, 1967]

§ 25.955

Fuel flow.

(a) Each fuel system must provide at

least 100 percent of the fuel flow re-
quired under each intended operating
condition and maneuver. Compliance
must be shown as follows:

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