Filiform Corrosion Associated with Commonly Applied Aircraft Metal Pretreatments and Finishes

The filiform corrosion problems encountered on aircraft structures in geographical areas experiencing constant warm temperature and elevated relative humidity indicate that finishing systems evaluations consisting of standard salt spray exposure do not adequately relate the efficiency of a system in inhibiting corrosion. An alternate method of testing is proposed: simulating the actual service environment with production of filiform corrosion on aluminum and steel alloys which have been pretreated and finished with commonly applied aircraft finishes. A comparison between salt spray exposure and this simulated service environment with coating and pretreatment evaluations is described.