> higher pressure air can hold more water at the same relative humidity The 787 and A350 cabins have higher relative humidity. > no. It's not rust, Citation

> higher pressure air can hold more water at the same relative humidity The 787 and A350 cabins have higher relative humidity. > no. It's not rust, Citation needed. Corrosion resistance is one of the most advertised benefits of the composite materials in those aircraft[1][2]. 1: http://www.lb.boeing.com/commercial/aeromagazine/articles/qtr_4_06/article_04_2.html http://www.lb.boeing.com/commercial/aeromagazine/articles/qt... 2: https://skybrary.aero/sites/default/files/bookshelf/3851.pdf https://skybrary.aero/sites/default/files/bookshelf/3851.pdf