491 

Federal Aviation Administration, DOT 

§ 25.1189 

with that paragraph need only be 
shown with the landing gear retracted. 

[Amdt. 25–11, 32 FR 6913, May 5, 1967] 

§ 25.1183

Flammable fluid-carrying 

components. 

(a) Except as provided in paragraph 

(b) of this section, each line, fitting, 
and other component carrying flam-
mable fluid in any area subject to en-
gine fire conditions, and each compo-
nent which conveys or contains flam-
mable fluid in a designated fire zone 
must be fire resistant, except that 
flammable fluid tanks and supports in 
a designated fire zone must be fireproof 
or be enclosed by a fireproof shield un-
less damage by fire to any non-fire-
proof part will not cause leakage or 
spillage of flammable fluid. Compo-
nents must be shielded or located to 
safeguard against the ignition of leak-
ing flammable fluid. An integral oil 
sump of less than 25-quart capacity on 
a reciprocating engine need not be fire-
proof nor be enclosed by a fireproof 
shield. 

(b) Paragraph (a) of this section does 

not apply to— 

(1) Lines, fittings, and components 

which are already approved as part of a 
type certificated engine; and 

(2) Vent and drain lines, and their fit-

tings, whose failure will not result in, 
or add to, a fire hazard. 

(c) All components, including ducts, 

within a designated fire zone must be 
fireproof if, when exposed to or dam-
aged by fire, they could— 

(1) Result in fire spreading to other 

regions of the airplane; or 

(2) Cause unintentional operation of, 

or inability to operate, essential serv-
ices or equipment. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–11, 32 FR 6913, May 5, 
1967; Amdt. 25–36, 39 FR 35461, Oct. 1, 1974; 
Amdt. 25–57, 49 FR 6849, Feb. 23, 1984; Amdt. 
25–101, 65 FR 79710, Dec. 19, 2000] 

§ 25.1185

Flammable fluids. 

(a) Except for the integral oil sumps 

specified in § 25.1183(a), no tank or res-
ervoir that is a part of a system con-
taining flammable fluids or gases may 
be in a designated fire zone unless the 
fluid contained, the design of the sys-
tem, the materials used in the tank, 
the shut-off means, and all connec-

tions, lines, and control provide a de-
gree of safety equal to that which 
would exist if the tank or reservoir 
were outside such a zone. 

(b) There must be at least one-half 

inch of clear airspace between each 
tank or reservoir and each firewall or 
shroud isolating a designated fire zone. 

(c) Absorbent materials close to 

flammable fluid system components 
that might leak must be covered or 
treated to prevent the absorption of 
hazardous quantities of fluids. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964 as 
amended by Amdt. 25–19, 33 FR 15410, Oct. 17, 
1968; Amdt. 25–94, 63 FR 8848, Feb. 23, 1998] 

§ 25.1187

Drainage and ventilation of 

fire zones. 

(a) There must be complete drainage 

of each part of each designated fire 
zone to minimize the hazards resulting 
from failure or malfunctioning of any 
component containing flammable 
fluids. The drainage means must be— 

(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. 

(c) No ventilation opening may be 

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 

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