493 

Federal Aviation Administration, DOT 

§ 25.1201 

installations that contain lines or com-
ponents carrying flammable fluids or 
gases for which it is shown that a fire 
originating in these sections can be 
controlled, there must be a fire extin-
guisher system serving each designated 
fire zone. 

(b) The fire extinguishing system, the 

quantity of the extinguishing agent, 
the rate of discharge, and the discharge 
distribution must be adequate to extin-
guish fires. It must be shown by either 
actual or simulated flights tests that 
under critical airflow conditions in 
flight the discharge of the extin-
guishing agent in each designated fire 
zone specified in paragraph (a) of this 
section will provide an agent con-
centration capable of extinguishing 
fires in that zone and of minimizing 
the probability of reignition. An indi-
vidual ‘‘one-shot’’ system may be used 
for auxiliary power units, fuel burning 
heaters, and other combustion equip-
ment. For each other designated fire 
zone, two discharges must be provided 
each of which produces adequate agent 
concentration. 

(c) The fire extinguishing system for 

a nacelle must be able to simulta-
neously protect each zone of the na-
celle for which protection is provided. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–46, 43 FR 50598, Oct. 30, 
1978] 

§ 25.1197

Fire extinguishing agents. 

(a) Fire extinguishing agents must— 
(1) Be capable of extinguishing 

flames emanating from any burning of 
fluids or other combustible materials 
in the area protected by the fire extin-
guishing system; and 

(2) Have thermal stability over the 

temperature range likely to be experi-
enced in the compartment in which 
they are stored. 

(b) If any toxic extinguishing agent is 

used, provisions must be made to pre-
vent harmful concentrations of fluid or 
fluid vapors (from leakage during nor-
mal operation of the airplane or as a 
result of discharging the fire extin-
guisher on the ground or in flight) from 
entering any personnel compartment, 
even though a defect may exist in the 
extinguishing system. This must be 
shown by test except for built-in car-

bon dioxide fuselage compartment fire 
extinguishing systems for which— 

(1) Five pounds or less of carbon diox-

ide will be discharged, under estab-
lished fire control procedures, into any 
fuselage compartment; or 

(2) There is protective breathing 

equipment for each flight crewmember 
on flight deck duty. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–38, 41 FR 55467, Dec. 20, 
1976; Amdt. 25–40, 42 FR 15044, Mar. 17, 1977] 

§ 25.1199

Extinguishing agent con-

tainers. 

(a) Each extinguishing agent con-

tainer must have a pressure relief to 
prevent bursting of the container by 
excessive internal pressures. 

(b) The discharge end of each dis-

charge line from a pressure relief con-
nection must be located so that dis-
charge of the fire extinguishing agent 
would not damage the airplane. The 
line must also be located or protected 
to prevent clogging caused by ice or 
other foreign matter. 

(c) There must be a means for each 

fire extinguishing agent container to 
indicate that the container has dis-
charged or that the charging pressure 
is below the established minimum nec-
essary for proper functioning. 

(d) The temperature of each con-

tainer must be maintained, under in-
tended operating conditions, to prevent 
the pressure in the container from— 

(1) Falling below that necessary to 

provide an adequate rate of discharge; 
or 

(2) Rising high enough to cause pre-

mature discharge. 

(e) If a pyrotechnic capsule is used to 

discharge the extinguishing agent, 
each container must be installed so 
that temperature conditions will not 
cause hazardous deterioration of the 
pyrotechnic capsule. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–23, 35 FR 5678, Apr. 8, 
1970; Amdt. 25–40, 42 FR 15044, Mar. 17, 1977] 

§ 25.1201

Fire extinguishing system 

materials. 

(a) No material in any fire extin-

guishing system may react chemically 
with any extinguishing agent so as to 
create a hazard. 

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