[Code of Federal Regulations] [Title 14, Volume 1] [Revised as of January 1, 2006] From the U.S. Government Printing Office via GPO Access [CITE: 14CFR31.39] [Page 762] TITLE 14--AERONAUTICS AND SPACE CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 31_AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS--Table of Contents Subpart D_Design Construction Sec. 31.39 Protection. Each part of the balloon must be suitably protected against deterioration or loss of strength in service due to weathering, corrosion, or other causes.