322
14 CFR Ch. I (1–1–24 Edition)
§ 25.991
where foreseeable maintenance ac-
tions, repairs, or alterations may com-
promise 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]
F
UEL
S
YSTEM
C
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.
(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 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 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
§ 25.721(b).
[Amdt. 25–139, 79 FR 59430, Oct. 2, 2014]
§ 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
accelerated flight conditions are trans-
mitted 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]
§ 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 displace-
ment 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;
(b) Have a sediment trap and drain
except that it need not have a drain if
the strainer or filter is easily remov-
able for drain purposes;
(c) Be mounted so that its weight is
not supported by the connecting lines
or by the inlet or outlet connections of
the strainer or filter itself, unless ade-
quate strength margins under all load-
ing conditions are provided in the lines
and connections; and
(d) Have the capacity (with respect to
operating limitations established for
the engine) to ensure that engine fuel
system functioning is not impaired,
with the fuel contaminated to a degree
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