Federal Aviation Administration, DOT

Section 25.1199

spaschal on DSK3GDR082PROD with CFR

vibration, inertia, and air load to
which it may be subjected in operation.
(b) Cowling must meet the drainage
and
ventilation
requirements
of
Section 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 subject to flame in case of fire in the engine power section of the powerplant
must - 
(1) Be fireproof; and
(2) Meet the requirements of Section 25.1191.
(d) Each part of the cowling subject
to high temperatures due to its nearness to exhaust system parts or exhaust gas impingement must be fireproof.
(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 section with the landing gear retracted (if
applicable); and
(3) Have fireproof skin in areas subject to flame if a fire starts in the engine power or accessory sections.
Section 25.1195 Fire extinguishing systems.
(a) Except for combustor, turbine,
and tail pipe sections of turbine engine
installations that contain lines or components 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 extinguisher 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 extinguish fires. It must be shown by either
actual or simulated flights tests that
under critical airflow conditions in
flight the discharge of the extinguishing agent in each designated fire
zone specified in paragraph (a) of this
section will provide an agent concentration capable of extinguishing
fires in that zone and of minimizing
the probability of reignition. An individual  - one-shot -  system may be used
for auxiliary power units, fuel burning

heaters, and other combustion equipment. 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 simultaneously protect each zone of the nacelle 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]

Section 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 extinguishing system; and
(2) Have thermal stability over the
temperature range likely to be experienced in the compartment in which
they are stored.
(b) If any toxic extinguishing agent is
used, provisions must be made to prevent harmful concentrations of fluid or
fluid vapors (from leakage during normal operation of the airplane or as a
result of discharging the fire extinguisher 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 carbon dioxide fuselage compartment fire
extinguishing systems for which - 
(1) Five pounds or less of carbon dioxide will be discharged, under established 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]

Section 25.1199 Extinguishing
agent
containers.
(a) Each extinguishing agent container must have a pressure relief to
prevent bursting of the container by
excessive internal pressures.
(b) The discharge end of each discharge line from a pressure relief connection must be located so that discharge of the fire extinguishing agent
would not damage the airplane. The

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