title-14-part-25-sec25-1193

335

Federal Aviation Administration, DOT

§ 25.1193

(1) Effective under conditions ex-

pected to prevail when drainage is
needed; and

(2) Arranged so that no discharged

fluid will cause an additional fire haz-
ard.

(b) Each designated fire zone must be

ventilated to prevent the accumulation
of flammable vapors.

where it would allow the entry of flam-
mable fluids, vapors, or flame from
other zones.

(d) Each ventilation means must be

arranged so that no discharged vapors
will cause an additional fire hazard.

(e) Unless the extinguishing agent ca-

pacity and rate of discharge are based
on maximum air flow through a zone,
there must be means to allow the crew
to shut off sources of forced ventilation
to any fire zone except the engine
power section of the nacelle and the
combustion heater ventilating air
ducts.

§ 25.1189

Shutoff means.

(a) Each engine installation and each

fire zone specified in § 25.1181(a)(4) and
(5) must have a means to shut off or
otherwise prevent hazardous quantities
of fuel, oil, deicer, and other flammable
fluids, from flowing into, within, or
through any designated fire zone, ex-
cept that shutoff means are not re-
quired for—

(1) Lines, fittings, and components

forming an integral part of an engine;
and

(2) Oil systems for turbine engine in-

stallations in which all components of
the system in a designated fire zone,
including oil tanks, are fireproof or lo-
cated in areas not subject to engine
fire conditions.

(b) The closing of any fuel shutoff

valve for any engine may not make
fuel unavailable to the remaining en-
gines.

interfere with the later emergency op-
eration of other equipment, such as the
means for feathering the propeller.

(d) Each flammable fluid shutoff

means and control must be fireproof or
must be located and protected so that
any fire in a fire zone will not affect its
operation.

(e) No hazardous quantity of flam-

mable fluid may drain into any des-
ignated fire zone after shutoff.

(f) There must be means to guard

against inadvertent operation of the
shutoff means and to make it possible
for the crew to reopen the shutoff
means in flight after it has been closed.

(g) Each tank-to-engine shutoff valve

must be located so that the operation
of the valve will not be affected by
powerplant or engine mount structural
failure.

(h) Each shutoff valve must have a

means to relieve excessive pressure ac-
cumulation unless a means for pressure
relief is otherwise provided in the sys-
tem.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–23, 35 FR 5677, Apr. 8,
1970; Amdt. 25–57, 49 FR 6849, Feb. 23, 1984]

§ 25.1191

Firewalls.

(a) Each engine, auxiliary power

unit, fuel-burning heater, other com-
bustion equipment intended for oper-
ation in flight, and the combustion,
turbine, and tailpipe sections of tur-
bine engines, must be isolated from the
rest of the airplane by firewalls,
shrouds, or equivalent means.

(b) Each firewall and shroud must

be—

(1) Fireproof;
(2) Constructed so that no hazardous

quantity of air, fluid, or flame can pass
from the compartment to other parts
of the airplane;

(3) Constructed so that each opening

is sealed with close fitting fireproof
grommets, bushings, or firewall fit-
tings; and

(4) Protected against corrosion.

§ 25.1192

Engine accessory section dia-

phragm.

For reciprocating engines, the engine

power section and all portions of the
exhaust system must be isolated from
the engine accessory compartment by a
diaphragm that complies with the fire-
wall requirements of § 25.1191.

[Amdt. 25–23, 35 FR 5678, Apr. 8, 1970]

§ 25.1193

Cowling and nacelle skin.

(a) Each cowling must be constructed

and supported so that it can resist any

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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.

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.

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