783 

Federal Aviation Administration, DOT 

§ 29.965 

and must be puncture resistant. Punc-
ture resistance must be shown by 
meeting the TSO-C80, paragraph 16.0, 
requirements using a minimum punc-
ture force of 370 pounds. 

(c) Each integral fuel tank must have 

facilities for inspection and repair of 
its interior. 

(d) The maximum exposed surface 

temperature of all components in the 
fuel tank must be less by a safe margin 
than the lowest expected autoignition 
temperature of the fuel or fuel vapor in 
the tank. Compliance with this re-
quirement must be shown under all op-
erating conditions and under all nor-
mal or malfunction conditions of all 
components inside the tank. 

(e) Each fuel tank installed in per-

sonnel compartments must be isolated 
by fume-proof and fuel-proof enclosures 
that are drained and vented to the ex-
terior 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 
§ 29.952, and must be adequate to with-
stand loads and abrasions to be ex-
pected in personnel compartments. 

[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] 

§ 29.965

Fuel tank tests. 

(a) Each fuel tank must be able to 

withstand the applicable pressure tests 
in this section without failure or leak-
age. If practicable, test pressures may 
be applied in a manner simulating the 
pressure distribution in service. 

(b) Each conventional metal tank, 

each nonmetallic tank with walls that 
are not supported by the rotorcraft 
structure, and each integral tank must 
be subjected to a pressure of 3.5 p.s.i. 
unless the pressure developed during 
maximum limit acceleration or emer-
gency deceleration with a full tank ex-
ceeds this value, in which case a hydro-
static 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 accelera-
tion 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 sec-
tion. 

(2) A pressure test, with the tank 

mounted in the rotorcraft structure, 
equal to the load developed by the re-
action of the contents, with the tank 
full, during maximum limit accelera-
tion or emergency deceleration. How-
ever, the pressure need not exceed 2.0 
p.s.i. on surfaces faces not exposed to 
the acceleration loading. 

(d) Each tank with large unsupported 

or unstiffened flat areas, or with other 
features whose failure or deformation 
could cause leakage, must be subjected 
to the following test or its equivalent: 

(1) Each complete tank assembly and 

its supports must be vibration tested 
while mounted to simulate the actual 
installation. 

(2) The tank assembly must be vi-

brated for 25 hours while two-thirds 
full of any suitable fluid. The ampli-
tude of vibration may not be less than 
one thirty-second of an inch, unless 
otherwise substantiated. 

(3) The test frequency of vibration 

must be as follows: 

(i) If no frequency of vibration result-

ing from any r.p.m. within the normal 
operating range of engine or rotor sys-
tem speeds is critical, the test fre-
quency of vibration, in number of cy-
cles per minute, must, unless a fre-
quency based on a more rational anal-
ysis is used, be the number obtained by 
averaging the maximum and minimum 
power-on engine speeds (r.p.m.) for re-
ciprocating engine powered rotorcraft 
or 2,000 c.p.m. for turbine engine pow-
ered rotorcraft. 

(ii) If only one frequency of vibration 

resulting from any r.p.m. within the 
normal operating range of engine or 
rotor system speeds is critical, that 
frequency of vibration must be the test 
frequency. 

(iii) If more than one frequency of vi-

bration resulting from any r.p.m. with-
in the normal operating range of en-
gine or rotor system speeds is critical, 
the most critical of these frequencies 
must be the test frequency. 

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