Text in force at 23-63: from 23-7, effective 14 Sep 1969.
[The fuel system must be designed and arranged to prevent the ignition of fuel vapor within the system by--
(a) Direct lightning strikes to area having a high probability of stroke attachment:
(b) Swept lightning strokes on area where swept strokes are highly probable; and
(c) Corona or streamering at fuel vent outlets.]
34 FR 13093 · Source