(ii)
If only one frequency of vibration resulting from any r.p.m. within the normal operating range of engine or rotor system speedsis critical, that frequency of vibration 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 or rotor system speeds is critical, the most critical of these frequencies must be the test fre-quency.

(4)
Under subparagraph(3)(ii) and(iii), the time of test mustbe adjusted to accomplishthe same number of vibration cycles as wouldbe accomplished in25hours atthefrequency speci.edin subparagraph(3)(i).

(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),aboutthemostcritical axis,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. 29-13, E.. 5/2/77
FAR 29.967 : Fuel tank installation.
(a)
Each fuel tank must be supported so that tank loads are not concentrated on unsupported 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 they are not required to withstand .uid loads; and

(4)
Each interior surface of tank compartments must be smooth and free of projections that could cause wear of the liner, unless–

(i)
There are meansforprotection of theliner atthosepoints; or

(ii)
The construction of the liner itself provides such protection.

(b)
Any spaces adjacent to tank surfaces must be adequately ventilated to avoid accumulation 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 that prevent excessive pressure resulting from al-titude changes. If .exible tank liners are installed, the venting arrangement for the spaces between the liner and its container must maintain the proper relationship totank ventpressuresforany expected .ightcondition.

(c)
The location of each tank must meet the requirements of Sec. 29.1185(b) and (c).

(d)
No rotorcraft skin immediately adjacent to a major air outlet from the engine compartment may act as the wall of an integral tank.

(e)
[[Removed.]] Amdt. 29-35, E.. 11/2/94

FAR 29.969 : Fuel tank expansion space.
[Eachfueltank or eachgroup offuel tanks withinterconnected vent systems must have an expansion space of not less than 2 percent of the combined tank capacity. It must be impossible to .ll the fuel tank expansion space inadvertently with the rotorcraft in the normal ground attitude.] Amdt. 29-26, E.. 10/3/88
FAR 29.971 : Fuel tank sump.
(a)
Each fuel tank must have a sump with a capacity of not less than the greater of–

(1)
0.10percent of thetank capacity or–

(2)
One-sixteenth gallon.

(b)
The capacityprescribedinparagraph(a) of this section must be e.ective with the rotorcraft in any normal attitude, and must be located so that the sump contents cannot escape through the tank outlet opening.

′
Elodie Roux. Septembre 2003
Subpart E : Powerplant
(c)
[ Each fuel tank must allow drainage of hazardous quantities of water from each part of the tank to the sump with the rotorcraft in any ground attitude to be expected in service.]

(d)
Each fuel tank sump must have a drain that allows complete drainage of the sump on the ground.
　
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