325 

Federal Aviation Administration, DOT 

§ 125.175 

§ 125.161

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 sub-
jected to flame, fire-extinguishing sys-
tems must be provided to serve all des-
ignated fire zones. 

(b) Materials in the fire-extin-

guishing system must not react chemi-
cally with the extinguishing agent so 
as to be a hazard. 

§ 125.163

Fire-extinguishing agents. 

Only methyl bromide, carbon dioxide, 

or another agent that has been shown 
to provide equivalent extinguishing ac-
tion may be used as a fire-extin-
guishing agent. If methyl bromide or 
any other toxic extinguishing agent is 
used, provisions must be made to pre-
vent harmful concentrations of fluid or 
fluid vapors from entering any per-
sonnel compartment either because of 
leakage during normal operation of the 
airplane or because of discharging the 
fire extinguisher on the ground or in 
flight when there is a defect in the ex-
tinguishing system. If a methyl bro-
mide system is used, the containers 
must be charged with dry agent and 
sealed by the fire-extinguisher manu-
facturer 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. 

§ 125.165

Extinguishing agent con-

tainer pressure relief. 

Extinguishing agent containers must 

be provided with a pressure relief to 
prevent bursting of the container be-
cause of excessive internal pressures. 
The discharge line from the relief con-
nection must terminate outside the 
airplane in a place convenient for in-
spection on the ground. An indicator 
must be provided at the discharge end 
of the line to provide a visual indica-
tion when the container has dis-
charged. 

§ 125.167

Extinguishing agent con-

tainer compartment temperature. 

Precautions must be taken to ensure 

that the extinguishing agent con-
tainers are installed in places where 
reasonable temperatures can be main-
tained for effective use of the extin-
guishing system. 

§ 125.169

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-resist-
ant and be located so as to minimize 
the probability of failure. 

§ 125.171

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. 

§ 125.173

Fire detectors. 

Fire detectors must be made and in-

stalled in a manner that assures their 
ability to resist, without failure, all vi-
bration, inertia, and other loads to 
which they may be normally subjected. 
Fire detectors must be unaffected by 
exposure to fumes, oil, water, or other 
fluids that may be present. 

§ 125.175

Protection of other airplane 

components against fire. 

(a) Except as provided in paragraph 

(b) of this section, all airplane surfaces 
aft of the nacelles in the area of one 
nacelle diameter on both sides of the 
nacelle centerline must be made of ma-
terial that is at least fire resistant. 

(b) Paragraph (a) of this section does 

not apply to tail surfaces lying behind 
nacelles unless the dimensional con-
figuration of the airplane is such that 
the tail surfaces could be affected read-
ily by heat, flames, or sparks ema-
nating from a designated fire zone or 
from the engine from a designated fire 
zone or from the engine compartment 
of any nacelle. 

VerDate Sep<11>2014 

08:20 May 17, 2019

Jkt 247048

PO 00000

Frm 00335

Fmt 8010

Sfmt 8002

Y:\SGML\247048.XXX

247048