Code of Federal Regulations - Title 14

479

Federal Aviation Administration, DOT

§ 25.995

or more engines and holds required fuel
reserves continually throughout each
flight.

not apply to a fuel tank if means are
provided to mitigate the effects of an
ignition of fuel vapors within that fuel
tank such that no damage caused by an
ignition will prevent continued safe
flight and landing.

(d) Critical design configuration con-

trol limitations (CDCCL), inspections,
or other procedures must be estab-
lished, as necessary, to prevent devel-
opment of ignition sources within the
fuel tank system pursuant to para-
graph (a) of this section, to prevent in-
creasing the flammability exposure of
the tanks above that permitted under
paragraph (b) of this section, and to
prevent degradation of the perform-
ance and reliability of any means pro-
vided according to paragraphs (a) or (c)
of this section. These CDCCL, inspec-
tions, and procedures must be included
in the Airworthiness Limitations sec-
tion of the instructions for continued
airworthiness required by § 25.1529.
Visible means of identifying critical
features of the design must be placed in
areas of the airplane where foreseeable
maintenance actions, repairs, or alter-
ations may compromise the critical de-
sign configuration control limitations
(e.g., color-coding of wire to identify
separation limitation). These visible
means must also be identified as
CDCCL.

[Doc. No. 1999–6411, 66 FR 23129, May 7, 2001,
as amended at Doc. No. FAA–2005–22997, 73
FR 42494, July 21, 2008]

UEL

YSTEM

OMPONENTS

§ 25.991

Fuel pumps.

(a)

Main pumps. Each fuel pump re-

quired for proper engine operation, or
required to meet the fuel system re-
quirements of this subpart (other than
those in paragraph (b) of this section,
is a main pump. For each main pump,
provision must be made to allow the
bypass of each positive displacement
fuel pump other than a fuel injection
pump (a pump that supplies the proper
flow and pressure for fuel injection
when the injection is not accomplished
in a carburetor) approved as part of the
engine.

(b)

Emergency pumps. There must be

emergency pumps or another main
pump to feed each engine immediately
after failure of any main pump (other
than a fuel injection pump approved as
part of the engine).

§ 25.993

Fuel system lines and fittings.

(a) Each fuel line must be installed

and supported to prevent excessive vi-
bration and to withstand loads due to
fuel pressure and accelerated flight
conditions.

(b) Each fuel line connected to com-

ponents of the airplane between which
relative motion could exist must have
provisions for flexibility.

lines that may be under pressure and
subjected to axial loading must use
flexible hose assemblies.

(d) Flexible hose must be approved or

must be shown to be suitable for the
particular application.

(e) No flexible hose that might be ad-

versely affected by exposure to high
temperatures may be used where exces-
sive temperatures will exist during op-
eration or after engine shut-down.

(f) Each fuel line within the fuselage

must be designed and installed to allow
a reasonable degree of deformation and
stretching without leakage.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–15, 32 FR 13266, Sept.
20, 1967]

§ 25.994

Fuel system components.

Fuel system components in an engine

nacelle or in the fuselage must be pro-
tected from damage which could result
in spillage of enough fuel to constitute
a fire hazard as a result of a wheels-up
landing on a paved runway.

[Amdt. 25–57, 49 FR 6848, Feb. 23, 1984]

§ 25.995

Fuel valves.

In addition to the requirements of

§ 25.1189 for shutoff means, each fuel
valve must—

(a) [Reserved]
(b) Be supported so that no loads re-

sulting from their operation or from

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