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 

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