(d)
Each tank with large unsupported or unsti.ened .at areas, or with other features whosefailure ordeformation could causeleakage, mustbe subjectedtothefollowing test or its equivalent :
(1)
Each complete tank assembly and its support must be vibration tested while mounted to simulate the actual installation.
(2)
The tank assembly must be vibrated for 25 hours while two-thirds full of any suitable .uid. The amplitude 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 resulting from any r.p.m. within the nor-mal operating range of engine or rotor system speeds is critical, the test frequency of vibration, in number of cycles per minute must, unless a frequencybased on a more rational calculationis used,be the number ob-tained by averaging the maximum and minimum power-on engine speeds (r.p.m.) for reciprocating engine powered rotorcraft or 2,000 c.p.m. for turbine engine powered 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.
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Elodie Roux. Septembre 2003
Subpart E : Powerplant
(iii) If more than one frequency of vibration resulting from any r.p.m. within the normal operating range of engine or rotor system speeds is critical, the most critical of these frequencies must be the test frequency.
(4)
Under paragraphs (d)(3)(ii) and (iii) of this section, the time of test must be adjusted to accomplish the same number of vibration cycles as would be accomplishedin25hours atthefrequency speci.edinparagraph(d)(3)(i) of this section.
(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 15 degrees on both sides of thehorizontal(30degreestotal), aboutthe most criticalaxis,for25hours. 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.]
Amdt. 27-12, E.. 5/2/77
FAR27.967 :[Fuel tankinstallation.]
(a)
[Each fuel tank must be supported so that tank loads are not concentrated on un-supported tank surfaces. In addition–
(1)
There must be pads, if necessary, to prevent cha.ng between each tank and its supports;
(2)
The padding must be nonabsorbent or treated to prevent the absorption of fuel;
(3)
If .exible tank liners are used, they must be supported so that it is not neces-sary for them to withstand .uid loads; and
(4)
Each interior surface of tank compartments must be smooth and free of pro-jections that couldcause wear of the liner unless–
(i)
There are meansforprotection oftheliner atthosepoints; or
(ii)
The construction of the liner itself provides such projection.
(b)
Any spaces adjacent to tank surfaces must be adequately ventilated to avoid ac-cumulation of fuel or fumes in those spaces due to minor leakage. If the tank is in a sealed compartment, ventilation may be limited to drain holes that prevent clogging and excessive pressure resulting from altitude changes. If .exible tank li-ners are installed, the venting arrangement for the spaces between the liner and its container must maintain the proper relationship to tank vent pressures for any expected .ight condition.
(c)
Thelocation of each tank must meetthe requirements ofSec.27.1185(a) and(c).
(d)
No rotorcraft skin immediately adjacent to a major air outlet from the engine com-partment may act as the wall of the integral tank.]
Amdt. 27-30, E.. 11/2/94
FAR 27.969 : Fuel tank expansion space
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本文链接地址：FAA规章 美国联邦航空规章 Federal Aviation Regulations 4(110)
