I usually buy ARF's for practice and fly-ins. that means I want to do the least to them to get them in the air. most come with some form of ply (usually Lt ply) for LG mounts. Marine ply is even a poor material here because a chain is only as strong as its weakest link, in the case of marine ply that is the glue between the ply layers. So on the typical ARF LG mounts I put a peace of .375x.375, or .25 x .5 maple under the ply. I want it to fit snugly between the ribs and use ample epoxy to hold it under where the retract mechanism ears will be. Left alone it wont take long for the movement in the ply to brake the ply bond. I mount the retract and get it all set up threading the sheet metal screws into the maple sandwiching the ply between the maple and retract mounting ears. The problem at this point is that the majority of stress still has to go through the ply which still gives the ply glue/lt ply as the weak point. To move the majority of the stress out of the ply I remove the retract mechanism and foam the entire area, so the foam is filling every nook and cranny in that wing bay. The next day when the foam is hardened up I cut out just what I need to fit the retract back in and a layer of fiberglass. Then I lay in 3ox of glass starting from the front LG mount, down the side of the foam, across the wing top sheeting, up the foam on the other side foam, and across the aft LG mount. Screw the LG back in and go fly. I’ve found this method to be as strong as if I did the install my self.

Joe

P.S. any Ideas for foam wings in my CMP fw190. I know what I would like to do but that would require a wing recover.