Composite Aircraft Lightning Strike Protection Damage Evaluation Using Microwave Microscopy

This article presents a new application of microwave microscopy as a diagnostic of the painted lightning strike protection (LSP) mesh used in composite aircraft skins. A new flexible probe is presented. This probe can sweep over the surface of the composite skin and detect breaks in the LSP lying underneath. It is demonstrated that shielding of the probe feeding line leads to better balancing, and consequently highly improved immunity to the presence of nearby objects. With this new approach, it is possible to localize faults as small as one cut strand under the paint. Also, this technique features the possibility to measure the paint thickness with a resolution on the order of micrometers.