Federal Aviation Administration, DOT

Section 25.997

those features, and prevent degradation of the performance and reliability
of any means provided according to
paragraphs (a), (b), or (c) of this section, the type design must also include
necessary inspection and test procedures, intervals between repetitive inspections and tests, and mandatory replacement times for those features.
The applicant must include information required by this paragraph in the
Airworthiness Limitations section of
the Instructions for Continued Airworthiness required by Section 25.1529. The
type design must also include visible
means of identifying critical features
of the design in areas of the airplane
where foreseeable maintenance actions, repairs, or alterations may compromise the CDCCLs.
[Doc. No. 1999-6411, 66 FR 23129, May 7, 2001,
as amended by Doc. No. FAA-2005-22997, 73
FR 42494, July 21, 2008; Doc. No. FAA- 2014-
1027, Amdt. No. 25-146, 83 FR 47556, Sept. 20,
2018]

FUEL SYSTEM COMPONENTS
Section 25.991

Fuel pumps.

(a) Main pumps. Each fuel pump required for proper engine operation, or
required to meet the fuel system requirements 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).

spaschal on DSK3GDR082PROD with CFR

Section 25.993

Fuel system lines and fittings.

(a) Each fuel line must be installed
and supported to prevent excessive vibration and to withstand loads due to
fuel pressure and accelerated flight
conditions.
(b) Each fuel line connected to components of the airplane between which

relative motion could exist must have
provisions for flexibility.
(c) Each flexible connection in fuel
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 adversely affected by exposure to high
temperatures may be used where excessive temperatures will exist during operation 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]

Section 25.994 Fuel system components.
Fuel system components in an engine
nacelle or in the fuselage must be protected from damage that could result
in spillage of enough fuel to constitute
a fire hazard as a result of a wheels-up
landing on a paved runway under each
of
the
conditions
prescribed
in
Section 25.721(b).
[Amdt. 25-139, 79 FR 59430, Oct. 2, 2014]

Section 25.995 Fuel valves.
In addition to the requirements of
Section 25.1189 for shutoff means, each fuel
valve must - 
(a) [Reserved]
(b) Be supported so that no loads resulting from their operation or from
accelerated flight conditions are transmitted to the lines attached to the
valve.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-40, 42 FR 15043, Mar. 17,
1977]

Section 25.997 Fuel strainer or filter.
There must be a fuel strainer or filter
between the fuel tank outlet and the
inlet of either the fuel metering device
or an engine driven positive displacement pump, whichever is nearer the
fuel tank outlet. This fuel strainer or
filter must - 
(a) Be accessible for draining and
cleaning and must incorporate a screen
or element which is easily removable;

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