14 C.F.R. § 31.39 Protection.
Title 14 - Aeronautics and Space
Each part of the balloon must be suitably protected against deterioration or loss of strength in service due to weathering, corrosion, or other causes.
Title 14: Aeronautics and Space
PART 31—AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS
Subpart D—Design Construction
§ 31.39 Protection.