14 C.F.R. § 27.954 Fuel system lightning protection.
Title 14 - Aeronautics and Space
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. [Amdt. 27–23, 53 FR 34212, Sept. 2, 1988]
Title 14: Aeronautics and Space
PART 27—AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT
Subpart E—Powerplant
Fuel System
§ 27.954 Fuel system lightning protection.