14 CFR §27.609

1. (a)Be suitably protected against deterioration or loss of strength in service due to any cause, including—
   1. (1)Weathering;
   2. (2)Corrosion; and
   3. (3)Abrasion; and
2. (b)Have provisions for ventilation and drainage where necessary to prevent the accumulation of corrosive, flammable, or noxious fluids.