Section 25.967

14 CFR Ch. I (1-1-19 Edition)

(d) For pressurized fuel tanks, it
must be shown by analysis or tests
that the fuel tanks can withstand the
maximum pressure likely to occur on
the ground or in flight.

tion may be shown with the means provided to comply with Section 25.979(b).

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-11, 32 FR 6913, May 5,
1967; Amdt. 25-40, 42 FR 15043, Mar. 17, 1977]

(a) Each fuel tank must have a sump
with an effective capacity, in the normal ground attitude, of not less than
the greater of 0.10 percent of the tank
capacity or one-sixteenth of a gallon
unless operating limitations are established to ensure that the accumulation
of water in service will not exceed the
sump capacity.
(b) Each fuel tank must allow drainage of any hazardous quantity of water
from any part of the tank to its sump
with the airplane in the ground attitude.
(c) Each fuel tank sump must have
an accessible drain that - 
(1) Allows complete drainage of the
sump on the ground;
(2) Discharges clear of each part of
the airplane; and
(3) Has manual or automatic means
for positive locking in the closed position.

Section 25.967

Fuel tank installations.

(a) Each fuel tank must be supported
so that tank loads (resulting from the
weight of the fuel in the tanks) are not
concentrated on unsupported tank surfaces. In addition - 
(1) There must be pads, if necessary,
to prevent chafing between the tank
and its supports;
(2) Padding must be nonabsorbent or
treated to prevent the absorption of
fluids;
(3) If a flexible tank liner is used, it
must be supported so that it is not required to withstand fluid loads; and
(4) Each interior surface of the tank
compartment must be smooth and free
of projections that could cause wear of
the liner unless - 
(i) Provisions are made for protection
of the liner at these points; or
(ii) The construction of the liner
itself provides that protection.
(b) Spaces adjacent to tank surfaces
must be ventilated to avoid fume accumulation due to minor leakage. If the
tank is in a sealed compartment, ventilation may be limited to drain holes
large enough to prevent excessive pressure resulting from altitude changes.
(c) The location of each tank must
meet the requirements of Section 25.1185(a).
(d) No engine nacelle skin immediately behind a major air outlet from
the engine compartment may act as
the wall of an integral tank.
(e) Each fuel tank must be isolated
from personnel compartments by a
fumeproof and fuelproof enclosure.

spaschal on DSK3GDR082PROD with CFR

Section 25.969

Fuel tank expansion space.

Each fuel tank must have an expansion space of not less than 2 percent of
the tank capacity. It must be impossible to fill the expansion space inadvertently with the airplane in the normal ground attitude. For pressure fueling systems, compliance with this sec-

[Amdt. 25-11, 32 FR 6913, May 5, 1967]

Section 25.971

Section 25.973

Fuel tank sump.

Fuel tank filler connection.

Each fuel tank filler connection must
prevent the entrance of fuel into any
part of the airplane other than the
tank itself. In addition - 
(a) [Reserved]
(b) Each recessed filler connection
that can retain any appreciable quantity of fuel must have a drain that discharges clear of each part of the airplane;
(c) Each filler cap must provide a
fuel-tight seal; and
(d) Each fuel filling point must have
a provision for electrically bonding the
airplane to ground fueling equipment.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-40, 42 FR 15043, Mar. 17,
1977; Amdt. 25-72, 55 FR 29785, July 20, 1990;
Amdt. 25-115, 69 FR 40527, July 2, 2004]

Section 25.975 Fuel tank vents and carburetor vapor vents.
(a) Fuel tank vents. Each fuel tank
must be vented from the top part of the
expansion space so that venting is effective under any normal flight condition. In addition - 

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