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14 CFR Ch. I (1–1–19 Edition) 

§ 125.147 

§ 125.147

Cowling. 

(a) Cowling must be made and sup-

ported so as to resist the vibration, in-
ertia, and air loads to which it may be 
normally subjected. 

(b) Provisions must be made to allow 

rapid and complete drainage of the 
cowling in normal ground and flight at-
titudes. Drains must not discharge in 
locations constituting a fire hazard. 
Parts of the cowling that are subjected 
to high temperatures because they are 
near exhaust system parts or because 
of exhaust gas impingement must be 
made of fireproof material. Unless oth-
erwise specified in these regulations, 
all other parts of the cowling must be 
made of material that is at least fire 
resistant. 

§ 125.149

Engine accessory section dia-

phragm. 

Unless equivalent protection can be 

shown by other means, a diaphragm 
that complies with § 125.145 must be 
provided on air-cooled engines to iso-
late the engine power section and all 
parts of the exhaust system from the 
engine accessory compartment. 

§ 125.151

Powerplant fire protection. 

(a) Designated fire zones must be pro-

tected from fire by compliance with 
§§ 125.153 through 125.159. 

(b) Designated fire zones are— 
(1) Engine accessory sections; 
(2) Installations where no isolation is 

provided between the engine and acces-
sory compartment; and 

(3) Areas that contain auxiliary 

power units, fuel-burning heaters, and 
other combustion equipment. 

§ 125.153

Flammable fluids. 

(a) No tanks or reservoirs that are a 

part of a system containing flammable 
fluids or gases may be located in des-
ignated fire zones, except where the 
fluid contained, the design of the sys-
tem, the materials used in the tank, 
the shutoff means, and the connec-
tions, lines, and controls provide equiv-
alent safety. 

(b) At least one-half inch of clear air-

space must be provided between any 
tank or reservior and a firewall or 
shroud isolating a designated fire zone. 

§ 125.155

Shutoff means. 

(a) Each engine must have a means 

for shutting off or otherwise pre-
venting hazardous amounts of fuel, oil, 
deicer, and other flammable fluids 
from flowing into, within, or through 
any designated fire zone. However, 
means need not be provided to shut off 
flow in lines that are an integral part 
of an engine. 

(b) The shutoff means must allow an 

emergency operating sequence that is 
compatible with the emergency oper-
ation of other equipment, such as 
feathering the propeller, to facilitate 
rapid and effective control of fires. 

(c) Shutoff means must be located 

outside of designated fire zones, unless 
equivalent safety is provided, and it 
must be shown that no hazardous 
amount of flammable fluid will drain 
into any designated fire zone after a 
shutoff. 

(d) Adequate provisions must be 

made to guard against inadvertent op-
eration of the shutoff means and to 
make it possible for the crew to reopen 
the shutoff means after it has been 
closed. 

§ 125.157

Lines and fittings. 

(a) Each line, and its fittings, that is 

located in a designated fire zone, if it 
carries flammable fluids or gases under 
pressure, or is attached directly to the 
engine, or is subject to relative motion 
between components (except lines and 
fittings forming an integral part of the 
engine), must be flexible and fire-re-
sistant with fire-resistant, factory- 
fixed, detachable, or other approved 
fire-resistant ends. 

(b) Lines and fittings that are not 

subject to pressure or to relative mo-
tion between components must be of 
fire-resistant materials. 

§ 125.159

Vent and drain lines. 

All vent and drain lines, and their 

fittings, that are located in a des-
ignated fire zone must, if they carry 
flammable fluids or gases, comply with 
§ 125.157, if the Administrator finds that 
the rupture or breakage of any vent or 
drain line may result in a fire hazard. 

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