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Federal Aviation Administration, DOT 

§ 27.859 

(b) The concentration of carbon mon-

oxide may not exceed one part in 20,000 
parts of air during forward flight or 
hovering in still air. If the concentra-
tion exceeds this value under other 
conditions, there must be suitable op-
erating restrictions. 

§ 27.833

Heaters. 

Each combustion heater must be ap-

proved. 

[Amdt. 27–23, 53 FR 34210, Sept. 2, 1988] 

F

IRE

P

ROTECTION

 

§ 27.853

Compartment interiors. 

For each compartment to be used by 

the crew or passengers— 

(a) The materials must be at least 

flame-resistant; 

(b) [Reserved] 
(c) If smoking is to be prohibited, 

there must be a placard so stating, and 
if smoking is to be allowed— 

(1) There must be an adequate num-

ber of self-contained, removable ash-
trays; and 

(2) Where the crew compartment is 

separated from the passenger compart-
ment, there must be at least one illu-
minated sign (using either letters or 
symbols) notifying all passengers when 
smoking is prohibited. Signs which no-
tify when smoking is prohibited must— 

(i) When illuminated, be legible to 

each passenger seated in the passenger 
cabin under all probable lighting condi-
tions; and 

(ii) Be so constructed that the crew 

can turn the illumination on and off. 

[Amdt. 27–17, 45 FR 7755, Feb. 4, 1980, as 
amended by Amdt. 27–37, 64 FR 45095, Aug. 18, 
1999] 

§ 27.855

Cargo and baggage compart-

ments. 

(a) Each cargo and baggage compart-

ment must be constructed of, or lined 
with, materials that are at least— 

(1) Flame resistant, in the case of 

compartments that are readily acces-
sible to a crewmember in flight; and 

(2) Fire resistant, in the case of other 

compartments. 

(b) No compartment may contain any 

controls, wiring, lines, equipment, or 
accessories whose damage or failure 
would affect safe operation, unless 
those items are protected so that— 

(1) They cannot be damaged by the 

movement of cargo in the compart-
ment; and 

(2) Their breakage or failure will not 

create a fire hazard. 

§ 27.859

Heating systems. 

(a)  General.  For each heating system 

that involves the passage of cabin air 
over, or close to, the exhaust manifold, 
there must be means to prevent carbon 
monoxide from entering any cabin or 
pilot compartment. 

(b)  Heat exchangers. Each heat ex-

changer must be— 

(1) Of suitable materials; 
(2) Adequately cooled under all con-

ditions; and 

(3) Easily disassembled for inspec-

tion. 

(c)  Combustion heater fire protection. 

Except for heaters which incorporate 
designs to prevent hazards in the event 
of fuel leakage in the heater fuel sys-
tem, fire within the ventilating air pas-
sage, or any other heater malfunction, 
each heater zone must incorporate the 
fire protection features of the applica-
ble requirements of §§ 27.1183, 27.1185, 
27.1189, 27.1191, and be provided with— 

(1) Approved, quick-acting fire detec-

tors in numbers and locations ensuring 
prompt detection of fire in the heater 
region. 

(2) Fire extinguisher systems that 

provide at least one adequate discharge 
to all areas of the heater region. 

(3) Complete drainage of each part of 

each zone to minimize the hazards re-
sulting from failure or malfunction of 
any component containing flammable 
fluids. The drainage means must be— 

(i) Effective under conditions ex-

pected to prevail when drainage is 
needed; and 

(ii) Arranged so that no discharged 

fluid will cause an additional fire haz-
ard. 

(4) Ventilation, arranged so that no 

discharged vapors will cause an addi-
tional fire hazard. 

(d)  Ventilating air ducts. Each ven-

tilating air duct passing through any 
heater region must be fireproof. 

(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 

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