background image

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

background image

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