Federal Aviation Administration, DOT

Section 125.145

Section 125.127 Location of fuel tanks.
(a) Fuel tanks must be located in accordance with Section 125.153.
(b) No part of the engine nacelle skin
that lies immediately behind a major
air outlet from the engine compartment may be used as the wall of an integral tank.
(c) Fuel tanks must be isolated from
personnel compartments by means of
fume- and fuel-proof enclosures.
Section 125.129 Fuel system lines and fittings.
(a) Fuel lines must be installed and
supported so as to prevent excessive vibration and so as to be adequate to
withstand loads due to fuel pressure
and accelerated flight conditions.
(b) Lines connected to components of
the airplane between which there may
be relative motion must incorporate
provisions for flexibility.
(c) Flexible connections in lines that
may be under pressure and subject to
axial loading must use flexible hose assemblies rather than hose clamp connections.
(d) Flexible hoses must be of an acceptable type or proven suitable for the
particular application.
Section 125.131 Fuel lines and fittings in designated fire zones.
Fuel lines and fittings in each designated fire zone must comply with
Section 125.157.
Section 125.133 Fuel valves.
Each fuel valve must - 
(a) Comply with Section 125.155;
(b) Have positive stops or suitable
index provisions in the  - on -  and  - off - 
positions; and
(c) Be supported so that loads resulting from its operation or from accelerated flight conditions are not transmitted to the lines connected to the
valve.
Section 125.135 Oil lines and fittings in designated fire zones.
Oil lines and fittings in each designated fire zone must comply with
Section 125.157.
Section 125.137 Oil valves.
(a) Each oil valve must - 
(1) Comply with Section 125.155;

(2) Have positive stops or suitable
index provisions in the  - on -  and  - off - 
positions; and
(3) Be supported so that loads resulting from its operation or from accelerated flight conditions are not transmitted to the lines attached to the
valve.
(b) The closing of an oil shutoff
means must not prevent feathering the
propeller, unless equivalent safety provisions are incorporated.
Section 125.139

Oil system drains.

Accessible drains incorporating either a manual or automatic means for
positive locking in the closed position
must be provided to allow safe drainage
of the entire oil system.
Section 125.141

Engine breather lines.

(a) Engine breather lines must be so
arranged that condensed water vapor
that may freeze and obstruct the line
cannot accumulate at any point.
(b) Engine breathers must discharge
in a location that does not constitute a
fire hazard in case foaming occurs and
so that oil emitted from the line does
not impinge upon the pilots- windshield.
(c) Engine breathers may not discharge into the engine air induction
system.
Section 125.143

Firewalls.

Each engine, auxiliary power unit,
fuel-burning heater, or other item of
combusting equipment that is intended
for operation in flight must be isolated
from the rest of the airplane by means
of firewalls or shrouds, or by other
equivalent means.
Section 125.145

Firewall construction.

Each firewall and shroud must - 
(a) Be so made that no hazardous
quantity of air, fluids, or flame can
pass from the engine compartment to
other parts of the airplane;
(b) Have all openings in the firewall
or shroud sealed with close-fitting fireproof grommets, bushings, or firewall
fittings;
(c) Be made of fireproof material; and
(d) Be protected against corrosion.

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