title-14-part-29-sec29-975

637

Federal Aviation Administration, DOT

§ 29.975

(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]

§ 29.969

Fuel tank expansion space.

Each fuel tank or each group of fuel

tanks with interconnected vent sys-
tems 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 inad-
vertently with the rotorcraft in the
normal ground attitude.

[Amdt. 29–26, 53 FR 34217, Sept. 2, 1988]

§ 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;

(2)

⁄

gallon.

(b) The capacity prescribed in para-

graph (a) of this section must be effec-
tive with the rotorcraft in any normal
attitude, and must be located so that
the sump contents cannot escape
through the tank outlet opening.

age of hazardous quantities of water
from each part of the tank to the sump
with the rotorcraft in any ground atti-
tude 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]

§ 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 oper-
ations and must be crash resistant dur-
ing a survivable impact in accordance
with § 29.952(c). In addition—

(1) Each filler must be marked as pre-

scribed in § 29.1557(c)(1);

(2) Each recessed filler connection

that can retain any appreciable quan-
tity 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 connec-
tion.

[Doc. No. 26352, 59 FR 50388, Oct. 3, 1994]

§ 29.975

Fuel tank vents and carbu-

retor vapor vents.

(a)

Fuel tank vents. Each fuel tank

must be vented from the top part of the
expansion space so that venting is ef-
fective under normal flight conditions.
In addition—

(1) The vents must be arranged to

avoid stoppage by dirt or ice forma-
tion;

(2) The vent arrangement must pre-

vent siphoning of fuel during normal
operation;

(3) The venting capacity and vent

pressure levels must maintain accept-
able differences of pressure between
the interior and exterior of the tank,
during—

(i) Normal flight operation;
(ii) Maximum rate of ascent and de-

scent; and

(iii) Refueling and defueling (where

applicable);

(4) Airspaces of tanks with inter-

connected outlets must be inter-
connected;

(5) There may be no point in any vent

line where moisture can accumulate
with the rotorcraft in the ground atti-
tude 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 de-

signed to minimize spillage of fuel
through the vents to an ignition source
in the event of a rollover during land-
ing, ground operations, or a survivable
impact.

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638

14 CFR Ch. I (1–1–24 Edition)

§ 29.977

(b)

Carburetor vapor vents. Each car-

buretor with vapor elimination connec-
tions must have a vent line to lead va-
pors back to one of the fuel tanks. In
addition—

(1) Each vent system must have

means to avoid stoppage by ice; and

(2) If there is more than one fuel

tank, and it is necessary to use the
tanks in a definite sequence, each
vapor vent return line must lead back
to the fuel tank used for takeoff and
landing.

[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;
Amdt. 29–42, 63 FR 43285, Aug. 12, 1998]

§ 29.977

Fuel tank outlet.

(a) There must be a fuel strainer for

the fuel tank outlet or for the booster
pump. This strainer must—

(1) For reciprocating engine powered

rotorcraft, have 8 to 16 meshes per
inch; and

(2) For turbine engine powered rotor-

craft, prevent the passage of any object
that could restrict fuel flow or damage
any fuel system component.

(b) The clear area of each fuel tank

outlet strainer must be at least five
times the area of the outlet line.

must be at least that of the fuel tank
outlet.

(d) Each finger strainer must be ac-

cessible for inspection and cleaning.

[Amdt. 29–12, 41 FR 55473, Dec. 20, 1976, as
amended by Amdt. 29–59, 88 FR 8739, Feb. 10,
2023]

§ 29.979

Pressure refueling and fueling

provisions below fuel level.

(a) Each fueling connection below the

fuel level in each tank must have
means to prevent the escape of haz-
ardous quantities of fuel from that
tank in case of malfunction of the fuel
entry valve.

(b) For systems intended for pressure

refueling, a means in addition to the
normal means for limiting the tank
content must be installed to prevent
damage to the tank in case of failure of
the normal means.

system (not fuel tanks and fuel tank
vents) must withstand an ultimate
load that is 2.0 times the load arising

from the maximum pressure, including
surge, that is likely to occur during
fueling. The maximum surge pressure
must be established with any combina-
tion of tank valves being either inten-
tionally or inadvertently closed.

(d) The rotorcraft defueling system

(not including fuel tanks and fuel tank
vents) must withstand an ultimate
load that is 2.0 times the load arising
from the maximum permissible
defueling pressure (positive or nega-
tive) at the rotorcraft fueling connec-
tion.

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–12, 41 FR 55473, Dec. 20,
1976]

UEL

YSTEM

OMPONENTS

§ 29.991

Fuel pumps.

(a) Compliance with § 29.955 must not

be jeopardized by failure of—

(1) Any one pump except pumps that

are approved and installed as parts of a
type certificated engine; or

(2) Any component required for pump

operation except the engine served by
that pump.

(b) The following fuel pump installa-

tion requirements apply:

(1) When necessary to maintain the

proper fuel pressure—

(i) A connection must be provided to

transmit the carburetor air intake
static pressure to the proper fuel pump
relief valve connection; and

(ii) The gauge balance lines must be

independently connected to the carbu-
retor inlet pressure to avoid incorrect
fuel pressure readings.

(2) The installation of fuel pumps

having seals or diaphragms that may
leak must have means for draining
leaking fuel.

(3) Each drain line must discharge

where it will not create a fire hazard.

[Amdt. 29–26, 53 FR 34217, Sept. 2, 1988]

§ 29.993

Fuel system lines and fittings.

(a) Each fuel line must be installed

and supported to prevent excessive vi-
bration and to withstand loads due to
fuel pressure, valve actuation, and ac-
celerated flight conditions.

(b) Each fuel line connected to com-

ponents of the rotorcraft between
which relative motion could exist must
have provisions for flexibility.