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308 

14 CFR Ch. I (1–1–24 Edition) 

§ 25.863 

(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 to 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 (e)(1) of this section for any 
individual heater must— 

(i) Be independent of components 

serving any other heater whose heat 
output is essential for safe operation; 
and 

(ii) Keep the heater off until re-

started by the crew. 

(3) There must be means to warn the 

crew when any heater whose heat out-
put is essential for safe operation has 
been shut off by the automatic means 
prescribed in paragraph (e)(1) of this 
section. 

(f) 

Air intakes. Each combustion and 

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

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

of any other component. 

(g) 

Heater exhaust. Heater exhaust 

systems must meet the provisions of 
§§ 25.1121 and 25.1123. In addition, there 
must be provisions in the design of the 
heater exhaust system to safely expel 
the products of combustion to prevent 
the occurrence of— 

(1) Fuel leakage from the exhaust to 

surrounding compartments; 

(2) Exhaust gas impingement on sur-

rounding equipment or structure; 

(3) Ignition of flammable fluids by 

the exhaust, if the exhaust is in a com-
partment containing flammable fluid 
lines; and 

(4) Restriction by the exhaust of the 

prompt relief of backfires that, if so re-
stricted, could cause heater failure. 

(h) 

Heater fuel systems. Each heater 

fuel system must meet each power-
plant fuel system requirement affect-
ing safe heater operation. Each heater 
fuel system component within the ven-
tilating airstream must be protected 
by shrouds so that no leakage from 
those components can enter the ven-
tilating airstream. 

(i) 

Drains.  There must be means to 

safely drain fuel that might accumu-
late within the combustion chamber or 
the heat exchanger. In addition— 

(1) Each part of any drain that oper-

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

(2) Each drain must be protected 

from hazardous ice accumulation under 
any operating condition. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–11, 32 FR 6912, May 5, 
1967; Amdt. 25–23, 35 FR 5676, Apr. 8, 1970] 

§ 25.863

Flammable fluid fire protec-

tion. 

(a) In each area where flammable 

fluids or vapors might escape by leak-
age of a fluid system, there must be 
means to minimize the probability of 
ignition of the fluids and vapors, and 
the resultant hazards if ignition does 
occur. 

(b) Compliance with paragraph (a) of 

this section must be shown by analysis 
or tests, and the following factors must 
be considered: 

(1) Possible sources and paths of fluid 

leakage, and means of detecting leak-
age. 

(2) Flammability characteristics of 

fluids, including effects of any combus-
tible or absorbing materials. 

(3) Possible ignition sources, includ-

ing electrical faults, overheating of 
equipment, and malfunctioning of pro-
tective devices. 

(4) Means available for controlling or 

extinguishing a fire, such as stopping 
flow of fluids, shutting down equip-
ment, fireproof containment, or use of 
extinguishing agents. 

(5) Ability of airplane components 

that are critical to safety of flight to 
withstand fire and heat. 

(c) If action by the flight crew is re-

quired to prevent or counteract a fluid 

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309 

Federal Aviation Administration, DOT 

§ 25.899 

fire (e.g., equipment shutdown or actu-
ation of a fire extinguisher) quick act-
ing means must be provided to alert 
the crew. 

(d) Each area where flammable fluids 

or vapors might escape by leakage of a 
fluid system must be identified and de-
fined. 

[Amdt. 25–23, 35 FR 5676, Apr. 8, 1970, as 
amended by Amdt. 25–46, 43 FR 50597, Oct. 30, 
1978] 

§ 25.865

Fire protection of flight con-

trols, engine mounts, and other 
flight structure. 

Essential flight controls, engine 

mounts, and other flight structures lo-
cated in designated fire zones or in ad-
jacent areas which would be subjected 
to the effects of fire in the fire zone 
must be constructed of fireproof mate-
rial or shielded so that they are capa-
ble of withstanding the effects of fire. 

[Amdt. 25–23, 35 FR 5676, Apr. 8, 1970] 

§ 25.867

Fire protection: other compo-

nents. 

(a) Surfaces to the rear of the na-

celles, within one nacelle diameter of 
the nacelle centerline, must be at least 
fire-resistant. 

(b) Paragraph (a) of this section does 

not apply to tail surfaces to the rear of 
the nacelles that could not be readily 
affected by heat, flames, or sparks 
coming from a designated fire zone or 
engine compartment of any nacelle. 

[Amdt. 25–23, 35 FR 5676, Apr. 8, 1970] 

§ 25.869

Fire protection: systems. 

(a) Electrical system components: 
(1) Components of the electrical sys-

tem must meet the applicable fire and 
smoke protection requirements of 
§§ 25.831(c) and 25.863. 

(2) Equipment that is located in des-

ignated fire zones and is used during 
emergency procedures must be at least 
fire resistant. 

(3) EWIS components must meet the 

requirements of § 25.1713. 

(b) Each vacuum air system line and 

fitting on the discharge side of the 
pump that might contain flammable 
vapors or fluids must meet the require-
ments of § 25.1183 if the line or fitting is 
in a designated fire zone. Other vacuum 
air systems components in designated 

fire zones must be at least fire resist-
ant. 

(c) Oxygen equipment and lines 

must— 

(1) Not be located in any designated 

fire zone, 

(2) Be protected from heat that may 

be generated in, or escape from, any 
designated fire zone, and 

(3) Be installed so that escaping oxy-

gen cannot cause ignition of grease, 
fluid, or vapor accumulations that are 
present in normal operation or as a re-
sult of failure or malfunction of any 
system. 

[Amdt. 25–72, 55 FR 29784, July 20, 1990, as 
amended by Amdt. 25–113, 69 FR 12530, Mar. 
16, 2004; Amdt. 25–123, 72 FR 63405, Nov. 8, 
2007] 

M

ISCELLANEOUS

 

§ 25.871

Leveling means. 

There must be means for determining 

when the airplane is in a level position 
on the ground. 

[Amdt. 25–23, 35 FR 5676, Apr. 8, 1970] 

§ 25.875

Reinforcement near propel-

lers. 

(a) Each part of the airplane near the 

propeller tips must be strong and stiff 
enough to withstand the effects of the 
induced vibration and of ice thrown 
from the propeller. 

(b) No window may be near the pro-

peller tips unless it can withstand the 
most severe ice impact likely to occur. 

§ 25.899

Electrical bonding and protec-

tion against static electricity. 

(a) Electrical bonding and protection 

against static electricity must be de-
signed to minimize accumulation of 
electrostatic charge that would cause— 

(1) Human injury from electrical 

shock, 

(2) Ignition of flammable vapors, or 
(3) Interference with installed elec-

trical/electronic equipment. 

(b) Compliance with paragraph (a) of 

this section may be shown by— 

(1) Bonding the components properly 

to the airframe; or 

(2) Incorporating other acceptable 

means to dissipate the static charge so 

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