title-14-part-27-sec27-859

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14 CFR Ch. I (1–1–24 Edition)

§ 27.831

Ventilation.

(a) The ventilating system for the

pilot and passenger compartments
must be designed to prevent the pres-
ence of excessive quantities of fuel
fumes and carbon monoxide.

(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]

IRE

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.

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§ 27.859

(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
that any fire originating in the heater
can be contained in the duct.

(2) Each part of any ventilating duct

passing through any region having a
flammable fluid system must be so
constructed or isolated from that sys-
tem that the malfunctioning of any
component of that system cannot in-
troduce flammable fluids or vapors
into the ventilating airstream.

(e)

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.

(1) No combustion air duct may con-

nect with the ventilating airstream un-
less flames from backfires or reverse
burning cannot enter the ventilating
airstream under any operating condi-
tion, including reverse flow or mal-
function of the heater or its associated
components.

(2) No combustion air duct may re-

strict the prompt relief of any backfire
that, if so restricted, could cause heat-
er failure.

(f)

Heater control: General. There must

be means to prevent the hazardous ac-
cumulation of water or ice on or in any
heater control component, control sys-
tem tubing, or safety control.

(g)

Heater safety controls. For each

combustion heater, safety control
means must be provided as follows:

(1) Means independent of the compo-

nents provided for the normal contin-
uous control of air temperature, air-
flow, and fuel flow must be provided for
each heater to automatically shut off
the ignition and fuel supply of that
heater at a point remote from that
heater when any of the following oc-
curs:

(i) The heat exchanger temperature

exceeds safe limits.

(ii) The ventilating air temperature

exceeds safe limits.

(iii) The combustion airflow becomes

inadequate for safe operation.

(iv) The ventilating airflow becomes

inadequate for safe operation.

(2) The means of complying with

paragraph (g)(1) of this section for any
individual heater must—

(i) Be independent of components

serving any other heater, the heat out-
put of which is essential for safe oper-
ation; and

(ii) Keep the heater off until re-

started by the crew.

(3) There must be means to warn the

crew when any heater, the heat output
of which is essential for safe operation,
has been shut off by the automatic
means prescribed in paragraph (g)(1) of
this section.

(h)

Air intakes. Each combustion and

ventilating air intake must be located
so that no flammable fluids or vapors
can enter the heater system—

(1) During normal operation; or
(2) As a result of the malfunction of

any other component.

(i)

Heater exhaust. Each heater ex-

haust system must meet the require-
ments of §§ 27.1121 and 27.1123.

(1) Each exhaust shroud must be

sealed so that no flammable fluids or
hazardous quantities of vapors can
reach the exhaust system through
joints.

(2) No exhaust system may restrict

the prompt relief of any backfire that,
if so restricted, could cause heater fail-
ure.

(j)

Heater fuel systems. Each heater

fuel system must meet the powerplant
fuel system requirements affecting safe
heater operation. Each heater fuel sys-
tem component in the ventilating air-
stream must be protected by shrouds
so that no leakage from those compo-
nents can enter the ventilating air-
stream.

(k)

Drains. There must be means for

safe drainage of any fuel that might ac-
cumulate in the combustion chamber
or the heat exchanger.

(1) Each part of any drain that oper-

ates at high temperatures must be pro-
tected in the same manner as heater
exhausts.

(2) Each drain must be protected

against hazardous ice accumulation
under any operating condition.

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–23, 53 FR 34211, Sept. 2,
1988]