Hi, I have some experience in sizing and detailed stress analysis. I am new to repair / structural modification justification work. I need to justify the frame web wherein new holes are added to install cabin lining (Plastic sheet). The weight is not significant. The number of fasteners per web (between 2 stringers)is limited to 2. My view to approach is like this. The interface loads at the lining installation are applied to web. From existing report find out the RF or applied load and the allowable. For example, if the failure mode shear buckling and then add the additional shear and check new RF. As case may be check for bending and shear interaction if applicable. I would like to know is there any other approaches to this problem. Thanks in advance.