I blocked the aft end of the spar and fibreglass tip with a shaped piece of high density foam, then layed up some epoxy and Aerosil mix, then topped the whole lot with epoxy and microballoons. I did the same along the rib, ensuring the foam was cut back at every rivet so the epoxy would bond behind the rivets and prevent the part dislodging and jamming the elevator horn. When that was done I secured a piece of ply over the rib to keep the microbubbles in place.
