Text in force at 27-51: from 27-23, effective 3 Oct 1988.
[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 to areas where swept strokes are highly probable; or
(c) Corona and streamering at fuel vent outlets.]
53 FR 34212 · Source