TITLE 14 - AERONAUTICS AND SPACE

CHAPTER I - FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION

SUBCHAPTER C - AIRCRAFT

PART 25 - AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

subpart d - DESIGN AND CONSTRUCTION

25.609 - Protection of structure.

Each part of the structure must (a) Be suitably protected against deterioration or loss of strength in service due to any cause, including (1) Weathering; (2) Corrosion; and (3) Abrasion; and (b) Have provisions for ventilation and drainage where necessary for protection.