The fuel system must be designed and arranged to prevent the ignition of fuel vapor within the system by--

(a) Direct lightning strikes to areas having a high probability of stroke attachment;

(b) Swept lightning strokes on areas where swept strokes are highly probable; and

(c) Corona or streamering at fuel vent outlets. [Amdt. 23-7, 34 FR 13093, Aug. 13, 1969]