(1)
An internal pressure of 3.5 p.s.i.
(2)
125percentofthe maximum airpressuredevelopedin the tankfrom ram e.ect.
(3)
Fluidpressuresdevelopedduringmaximumlimit accelerations, andde.ections, of the airplane with a full tank.
(4)
Fluidpressuresdevelopedduringthe most adverse combination of airplane roll and fuel load.
(b)
Each metallictank withlargeunsupported orunsti.ened .at surfaces,whosefailure or deformation could cause fuel leakage, must be able to withstand the following test, or its equivalent, without leakage or excessive deformation of the tank walls :
(1)
Each complete tank assembly and its supports must be vibration tested while mounted to simulate the actual installation.
(2)
Except as speci.edin subparagraph(4) ofthisparagraph,the tank assembly must be vibrated for 25 hours at an amplitude of not less than 1/32 of an inch(unlessanotheramplitudeissubstantiated) while2/3 .lledwithwater or other suitable test .uid.
(3)
The test frequency of vibration must be as follows :
(i)
If no frequency of vibration resulting from any r.p.m. within the normal operating range of engine speedsis critical, the testfrequency of vibration must be 2,000 cycles per minute.
(ii)
If only one frequency of vibration resulting from any r.p.m. within the normal operating range of engine speeds is critical, that frequency of vi-bration must be the test frequency.
(iii) If more than one frequency of vibration resulting from any r.p.m. within the normal operating range of engine speeds is critical, the most critical of these frequencies must be the test frequency.
(4)
Under subparagraph(3)(ii) and(iii) of thisparagraph,the time of test must be adjusted to accomplish the same number of vibration cycles that would be accomplishedin25hours atthefrequency speci.edin subparagraph(3)(i) of this paragraph.
(5)
During the test, the tank assembly must be rocked at the rate of 16 to 20
'
complete cycles per minute, through an angle of 15on both sides of the
'
horizontal (30total), about the most critical axis, for 25 hours. If motion about more than one axis is likely to be critical, the tank must be rocked about each critical axis for 12 1/2 hours.
(c)
Exceptwhere satisfactory operating experience with a similartankin a similarinstal-lation is shown, nonmetallic tanks must withstand the test speci.ed in paragraph (b)(5) of this section, with fuel at a temperature of 110'F. During this test, a representative specimen of the tank must be installed in a supporting structure simulating the installation in the airplane.
(d)
[Forpressurizedfueltanks,it mustbe shownby analysisorteststhatthefuel tanks can withstand the maximum pressure likely to occur on the ground or in .ight.]
Amdt. 25-40, E.. 5/2/77
FAR 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 cha.ng between the tank and its supports;
(2)
Padding mustbenonabsorbentortreated topreventtheabsorptionof .uids;
(3)
If a .exible tank liner is used, it must be supported so that it is not required to withstand .uid 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 mustbe ventilated to avoidfume accumulationdue to minorleakage.If the tankisin a sealed compartment, ventilation maybelimited to drain holes large enough to prevent excessive pressure resulting from altitude changes.
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本文链接地址：FAA规章 美国联邦航空规章 Federal Aviation Regulations 3(116)
