Section 29.969

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

(d) No rotorcraft skin immediately
adjacent to a major air outlet from the
engine compartment may act as the
wall of an integral tank.
[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29-26, 53 FR 34217, Sept. 2,
1988; Amdt. 29-35, 59 FR 50388, Oct. 3, 1994]

Section 29.969

Fuel tank expansion space.

Each fuel tank or each group of fuel
tanks with interconnected vent systems must have an expansion space of
not less than 2 percent of the combined
tank capacity. It must be impossible to
fill the fuel tank expansion space inadvertently with the rotorcraft in the
normal ground attitude.
[Amdt. 29-26, 53 FR 34217, Sept. 2, 1988]

Section 29.971

Fuel tank sump.

(a) Each fuel tank must have a sump
with a capacity of not less than the
greater of - 
(1) 0.10 per cent of the tank capacity;
or
(2) 1-16 gallon.
(b) The capacity prescribed in paragraph (a) of this section must be effective with the rotorcraft in any normal
attitude, and must be located so that
the sump contents cannot escape
through the tank outlet opening.
(c) Each fuel tank must allow drainage of hazardous quantities of water
from each part of the tank to the sump
with the rotorcraft in any ground attitude to be expected in service.
(d) Each fuel tank sump must have a
drain that allows complete drainage of
the sump on the ground.
[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29-12, 41 FR 55473, Dec. 20,
1976; Amdt. 29-26, 53 FR 34217, Sept. 2, 1988]

spaschal on DSK3GDR082PROD with CFR

Section 29.973

Fuel tank filler connection.

(a) Each fuel tank filler connection
must prevent the entrance of fuel into
any part of the rotorcraft other than
the tank itself during normal operations and must be crash resistant during a survivable impact in accordance
with Section 29.952(c). In addition - 
(1) Each filler must be marked as prescribed in Section 29.1557(c)(1);
(2) Each recessed filler connection
that can retain any appreciable quantity of fuel must have a drain that dis-

charges clear of the entire rotorcraft;
and
(3) Each filler cap must provide a
fuel-tight seal under the fluid pressure
expected in normal operation and in a
survivable impact.
(b) Each filler cap or filler cap cover
must warn when the cap is not fully
locked or seated on the filler connection.
[Doc. No. 26352, 59 FR 50388, Oct. 3, 1994]

Section 29.975 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 normal flight conditions.
In addition - 
(1) The vents must be arranged to
avoid stoppage by dirt or ice formation;
(2) The vent arrangement must prevent siphoning of fuel during normal
operation;
(3) The venting capacity and vent
pressure levels must maintain acceptable differences of pressure between
the interior and exterior of the tank,
during - 
(i) Normal flight operation;
(ii) Maximum rate of ascent and descent; and
(iii) Refueling and defueling (where
applicable);
(4) Airspaces of tanks with interconnected outlets must be interconnected;
(5) There may be no point in any vent
line where moisture can accumulate
with the rotorcraft in the ground attitude or the level flight attitude, unless
drainage is provided;
(6) No vent or drainage provision may
end at any point - 
(i) Where the discharge of fuel from
the vent outlet would constitute a fire
hazard; or
(ii) From which fumes could enter
personnel compartments; and
(7) The venting system must be designed to minimize spillage of fuel
through the vents to an ignition source
in the event of a rollover during landing, ground operations, or a survivable
impact.

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