336 

14 CFR Ch. I (1–1–24 Edition) 

§ 25.1195 

vibration, inertia, and air load to 
which it may be subjected in operation. 

(b) Cowling must meet the drainage 

and ventilation requirements of 
§ 25.1187. 

(c) On airplanes with a diaphragm 

isolating the engine power section from 
the engine accessory section, each part 
of the accessory section cowling sub-
ject to flame in case of fire in the en-
gine power section of the powerplant 
must— 

(1) Be fireproof; and 
(2) Meet the requirements of § 25.1191. 
(d) Each part of the cowling subject 

to high temperatures due to its near-
ness to exhaust system parts or ex-
haust gas impingement must be fire-
proof. 

(e) Each airplane must— 
(1) Be designed and constructed so 

that no fire originating in any fire zone 
can enter, either through openings or 
by burning through external skin, any 
other zone or region where it would 
create additional hazards; 

(2) Meet paragraph (e)(1) of this sec-

tion with the landing gear retracted (if 
applicable); and 

(3) Have fireproof skin in areas sub-

ject to flame if a fire starts in the en-
gine power or accessory sections. 

§ 25.1195

Fire extinguishing systems. 

(a) Except for combustor, turbine, 

and tail pipe sections of turbine engine 
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 

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