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
VerDate Sep<11>2014
09:06 Jun 28, 2024
Jkt 262046
PO 00000
Frm 00332
Fmt 8010
Sfmt 8010
Y:\SGML\262046.XXX
262046
jspears on DSK121TN23PROD with CFR
323
Federal Aviation Administration, DOT
§ 25.1001
(with respect to particle size and den-
sity) that is greater than that estab-
lished for the engine in Part 33 of this
chapter.
[Amdt. 25–36, 39 FR 35460, Oct. 1, 1974, as
amended by Amdt. 25–57, 49 FR 6848, Feb. 23,
1984]
§ 25.999
Fuel system drains.
(a) Drainage of the fuel system must
be accomplished by the use of fuel
strainer and fuel tank sump drains.
(b) Each drain required by paragraph
(a) of this section must—
(1) Discharge clear of all parts of the
airplane;
(2) Have manual or automatic means
for positive locking in the closed posi-
tion; and
(3) Have a drain valve—
(i) That is readily accessible and
which can be easily opened and closed;
and
(ii) That is either located or pro-
tected to prevent fuel spillage in the
event of a landing with landing gear re-
tracted.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–38, 41 FR 55467, Dec. 20,
1976]
§ 25.1001
Fuel jettisoning system.
(a) A fuel jettisoning system must be
installed on each airplane unless it is
shown that the airplane meets the
climb requirements of §§ 25.119 and
25.121(d) at maximum takeoff weight,
less the actual or computed weight of
fuel necessary for a 15-minute flight
comprised of a takeoff, go-around, and
landing at the airport of departure
with the airplane configuration, speed,
power, and thrust the same as that
used in meeting the applicable takeoff,
approach, and landing climb perform-
ance requirements of this part.
(b) If a fuel jettisoning system is re-
quired it must be capable of jettisoning
enough fuel within 15 minutes, starting
with the weight given in paragraph (a)
of this section, to enable the airplane
to meet the climb requirements of
§§ 25.119 and 25.121(d), assuming that the
fuel is jettisoned under the conditions,
except weight, found least favorable
during the flight tests prescribed in
paragraph (c) of this section.
(c) Fuel jettisoning must be dem-
onstrated beginning at maximum take-
off weight with flaps and landing gear
up and in—
(1) A power-off glide at 1.3 V
SR1
;
(2) A climb at the one-engine inoper-
ative best rate-of-climb speed, with the
critical engine inoperative and the re-
maining engines at maximum contin-
uous power; and
(3) Level flight at 1.3 V
SR1
; if the re-
sults of the tests in the conditions
specified in paragraphs (c)(1) and (2) of
this section show that this condition
could be critical.
(d) During the flight tests prescribed
in paragraph (c) of this section, it must
be shown that—
(1) The fuel jettisoning system and
its operation are free from fire hazard;
(2) The fuel discharges clear of any
part of the airplane;
(3) Fuel or fumes do not enter any
parts of the airplane; and
(4) The jettisoning operation does not
adversely affect the controllability of
the airplane.
(e) For reciprocating engine powered
airplanes, means must be provided to
prevent jettisoning the fuel in the
tanks used for takeoff and landing
below the level allowing 45 minutes
flight at 75 percent maximum contin-
uous power. However, if there is an
auxiliary control independent of the
main jettisoning control, the system
may be designed to jettison the re-
maining fuel by means of the auxiliary
jettisoning control.
(f) For turbine engine powered air-
planes, means must be provided to pre-
vent jettisoning the fuel in the tanks
used for takeoff and landing below the
level allowing climb from sea level to
10,000 feet and thereafter allowing 45
minutes cruise at a speed for maximum
range. However, if there is an auxiliary
control independent of the main jetti-
soning control, the system may be de-
signed to jettison the remaining fuel
by means of the auxiliary jettisoning
control.
(g) The fuel jettisoning valve must be
designed to allow flight personnel to
close the valve during any part of the
jettisoning operation.
(h) Unless it is shown that using any
means (including flaps, slots, and slats)
for changing the airflow across or
around the wings does not adversely af-
fect fuel jettisoning, there must be a
VerDate Sep<11>2014
09:06 Jun 28, 2024
Jkt 262046
PO 00000
Frm 00333
Fmt 8010
Sfmt 8010
Y:\SGML\262046.XXX
262046
jspears on DSK121TN23PROD with CFR