Section 27.963

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

by test to operate satisfactorily (within certification limits) when using fuel
at a temperature of 110 SectionF under critical operating conditions including, if
applicable, the engine operating conditions defined by Section 27.927 (b)(1) and (b)(2).
[Amdt. 27-23, 53 FR 34212, Sept. 2, 1988]

spaschal on DSK3GDR082PROD with CFR

Section 27.963

Fuel tanks: general.

(a) Each fuel tank must be able to
withstand, without failure, the vibration, inertia, fluid, and structural loads
to which it may be subjected in operation.
(b) Each fuel tank of 10 gallons or
greater capacity must have internal
baffles, or must have external support
to resist surging.
(c) Each fuel tank must be separated
from the engine compartment by a
firewall. At least one-half inch of clear
airspace must be provided between the
tank and the firewall.
(d) Spaces adjacent to the surfaces of
fuel tanks must be ventilated so that
fumes cannot accumulate in the tank
compartment in case of leakage. If two
or more tanks have interconnected
outlets, they must be considered as one
tank, and the airspaces in those tanks
must be interconnected to prevent the
flow of fuel from one tank to another
as a result of a difference in pressure
between those airspaces.
(e) The maximum exposed surface
temperature of any component in the
fuel tank must be less, by a safe margin as determined by the Administrator, than the lowest expected
autoignition temperature of the fuel or
fuel vapor in the tank. Compliance
with this requirement must be shown
under all operating conditions and
under all failure or malfunction conditions of all components inside the
tank.
(f) Each fuel tank installed in personnel compartments must be isolated
by fume-proof and fuel-proof enclosures
that are drained and vented to the exterior of the rotorcraft. The design and
construction of the enclosures must
provide necessary protection for the
tank, must be crash resistant during a
survivable impact in accordance with
Section 27.952, and must be adequate to withstand loads and abrasions to be expected in personnel compartments.

(g) Each flexible fuel tank bladder or
liner must be approved or shown to be
suitable for the particular application
and must be puncture resistant. Puncture resistance must be shown by
meeting the TSO-C80, paragraph 16.0,
requirements using a minimum puncture force of 370 pounds.
(h) Each integral fuel tank must have
provisions for inspection and repair of
its interior.
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27-23, 53 FR 34213, Sept. 2,
1988; Amdt. 27-30, 59 FR 50387, Oct. 3, 1994]

Section 27.965

Fuel tank tests.

(a) Each fuel tank must be able to
withstand the applicable pressure tests
in this section without failure or leakage. If practicable, test pressures may
be applied in a manner simulating the
pressure distribution in service.
(b) Each conventional metal tank,
nonmetallic tank with walls that are
not supported by the rotorcraft structure, and integral tank must be subjected to a pressure of 3.5 p.s.i. unless
the pressure developed during maximum limit acceleration or emergency
deceleration with a full tank exceeds
this value, in which case a hydrostatic
head, or equivalent test, must be applied to duplicate the acceleration
loads as far as possible. However, the
pressure need not exceed 3.5 p.s.i. on
surfaces not exposed to the acceleration loading.
(c) Each nonmetallic tank with walls
supported by the rotorcraft structure
must be subjected to the following
tests:
(1) A pressure test of at least 2.0 p.s.i.
This test may be conducted on the
tank alone in conjunction with the test
specified in paragraph (c)(2) of this section.
(2) A pressure test, with the tank
mounted in the rotorcraft structure,
equal to the load developed by the reaction of the contents, with the tank
full, during maximum limit acceleration or emergency deceleration. However, the pressure need not exceed 2.0
p.s.i. on surfaces not exposed to the acceleration loading.
(d) Each tank with large unsupported
or unstiffened flat areas, or with other
features whose failure or deformation

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