306 

14 CFR Ch. I (1–1–19 Edition) 

§ 25.858 

(2) There is a separate approved 

smoke or fire detector system to give 
warning at the pilot or flight engineer 
station; 

(3) There are means to shut off the 

ventilating airflow to, or within, the 
compartment, and the controls for 
these means are accessible to the flight 
crew in the crew compartment; 

(4) There are means to exclude haz-

ardous quantities of smoke, flames, or 
noxious gases, from the flight crew 
compartment; and 

(5) The required crew emergency 

exits are accessible under any cargo 
loading condition. 

(f) Class F. A Class F cargo or bag-

gage compartment must be located on 
the main deck and is one in which— 

(1) There is a separate approved 

smoke detector or fire detector system 
to give warning at the pilot or flight 
engineer station; 

(2) There are means to extinguish or 

control a fire without requiring a crew-
member to enter the compartment; and 

(3) There are means to exclude haz-

ardous quantities of smoke, flames, or 
extinguishing agent from any compart-
ment occupied by the crew or pas-
sengers. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–32, 37 FR 3972, Feb. 24, 
1972; Amdt. 25–60, 51 FR 18243, May 16, 1986; 
Amdt. 25–93, 63 FR 8048, Feb. 17, 1998; Doc. 
No. Docket FAA–2014–0001, Amdt. 25–142, 81 
FR 7704, Feb. 16, 2016] 

§ 25.858

Cargo or baggage compart-

ment smoke or fire detection sys-
tems. 

If certification with cargo or baggage 

compartment smoke or fire detection 
provisions is requested, the following 
must be met for each cargo or baggage 
compartment with those provisions: 

(a) The detection system must pro-

vide a visual indication to the flight 
crew within one minute after the start 
of a fire. 

(b) The system must be capable of de-

tecting a fire at a temperature signifi-
cantly below that at which the struc-
tural integrity of the airplane is sub-
stantially decreased. 

(c) There must be means to allow the 

crew to check in flight, the functioning 
of each fire detector circuit. 

(d) The effectiveness of the detection 

system must be shown for all approved 

operating configurations and condi-
tions. 

[Amdt. 25–54, 45 FR 60173, Sept. 11, 1980, as 
amended by Amdt. 25–93, 63 FR 8048, Feb. 17, 
1998] 

§ 25.859

Combustion heater fire pro-

tection. 

(a) 

Combustion heater fire zones. 

The 

following combustion heater fire zones 
must be protected from fire in accord-
ance with the applicable provisions of 
§§ 25.1181 through 25.1191 and §§ 25.1195 
through 25.1203; 

(1) The region surrounding the heat-

er, if this region contains any flam-
mable fluid system components (ex-
cluding the heater fuel system), that 
could— 

(i) Be damaged by heater malfunc-

tioning; or 

(ii) Allow flammable fluids or vapors 

to reach the heater in case of leakage. 

(2) The region surrounding the heat-

er, if the heater fuel system has fit-
tings that, if they leaked, would allow 
fuel or vapors to enter this region. 

(3) The part of the ventilating air 

passage that surrounds the combustion 
chamber. However, no fire extinguish-
ment is required in cabin ventilating 
air passages. 

(b) 

Ventilating air ducts. 

Each ven-

tilating air duct passing through any 
fire zone must be fireproof. In addi-
tion— 

(1) Unless isolation is provided by 

fireproof valves or by equally effective 
means, the ventilating air duct down-
stream of each heater must be fireproof 
for a distance great enough to ensure 
that any fire originating in the heater 
can be contained in the duct; and 

(2) Each part of any ventilating duct 

passing through any region having a 
flammable fluid system must be con-
structed or isolated from that system 
so that the malfunctioning of any com-
ponent of that system cannot intro-
duce flammable fluids or vapors into 
the ventilating airstream. 

(c) 

Combustion air ducts. 

Each com-

bustion air duct must be fireproof for a 
distance great enough to prevent dam-
age from backfiring or reverse flame 
propagation. In addition— 

(1) No combustion air duct may have 

a common opening with the ventilating 
airstream unless flames from backfires 

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