This paper describes a computer analysis developed to evaluate the expected lightning induced transients in a critical aircraft equipment interfacing an externally mounted sensor subject to a direct lightning attachment. At first, a discussion of the coupling mechanism in a metal airframe is presented. Once it is established an understanding of the coupling process, by modeling and testing a metal airframe, the article progresses to the evaluation of a case where the skin material is replaced by a quasi-isotropic carbon fiber composite laminate. Finally, it was also investigated the effects of the inclusion of a metal strip, to divert the current from the cabling, and the addition of cable raceways in the composite mounted installation. The results found for lightning induced transients, in each different proposed installation, provided valuable comparative effects expected for each airframe construction design and an indication of the level of protection to be considered for each respective system application.