Federal Aviation Administration, DOT

Section 121.275
flight when there is a defect in the extinguishing system. If a methyl bromide system is used, the containers
must be charged with dry agent and
sealed by the fire-extinguisher manufacturer or some other person using
satisfactory recharging equipment. If
carbon dioxide is used, it must not be
possible to discharge enough gas into
the personnel compartments to create
a danger of suffocating the occupants.

make it possible for the crew to reopen
the shutoff means after it has been
closed.
Section 121.259 Lines and fittings.
(a) Each line, and its fittings, that is
located in a designated fire zone, if it
carries flammable fluids or gases under
pressure, or is attached directly to the
engine, or is subject to relative motion
between components (except lines and
fittings forming an integral part of the
engine), must be flexible and fire-resistant with fire-resistant, factoryfixed, detachable, or other approved
fire-resistant ends.
(b) Lines and fittings that are not
subject to pressure or to relative motion between components must be of
fire-resistant materials.

Section 121.267 Extinguishing
agent
container pressure relief.
Extinguishing agent containers must
be provided with a pressure relief to
prevent bursting of the container because of excessive internal pressures.
The discharge line from the relief connection must terminate outside the
airplane in a place convenient for inspection on the ground. An indicator
must be provided at the discharge end
of the line to provide a visual indication when the container has discharged.

Section 121.261 Vent and drain lines.
All vent and drain lines and their fittings, that are located in a designated
fire zone must, if they carry flammable
fluids or gases, comply with Section 121.259, if
the Administrator finds that the rupture or breakage of any vent or drain
line may result in a fire hazard.

Section 121.269 Extinguishing
agent
container compartment temperature.
Precautions must be taken to insure
that the extinguishing agent containers are installed in places where
reasonable temperatures can be maintained for effective use of the extinguishing system.

Section 121.263 Fire-extinguishing systems.
(a) Unless the certificate holder
shows that equivalent protection
against destruction of the airplane in
case of fire is provided by the use of
fireproof materials in the nacelle and
other components that would be subjected to flame, fire-extinguishing systems must be provided to serve all designated fire zones.
(b) Materials in the fire-extinguishing system must not react chemically with the extinguishing agent so
as to be a hazard.

Section 121.271 Fire-extinguishing
system
materials.
(a) Except as provided in paragraph
(b) of this section, each component of a
fire-extinguishing system that is in a
designated fire zone must be made of
fireproof materials.
(b) Connections that are subject to
relative motion between components of
the airplane must be made of flexible
materials that are at least fire-resistant and be located so as to minimize
the probability of failure.

Section 121.265 Fire-extinguishing agents.
Only methyl bromide, carbon dioxide,
or another agent that has been shown
to provide equivalent extinguishing action may be used as a fire-extinguishing agent. If methyl bromide or
any other toxic extinguishing agent is
used, provisions must be made to prevent harmful concentrations of fluid or
fluid vapors from entering any personnel compartment either because of
leakage during normal operation of the
airplane or because of discharging the
fire extinguisher on the ground or in

Section 121.273 Fire-detector systems.
Enough quick-acting fire detectors
must be provided in each designated
fire zone to assure the detection of any
fire that may occur in that zone.
Section 121.275 Fire detectors.
Fire detectors must be made and installed in a manner that assures their

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