Try to purchase the same covering material that was used on the plane: Monocote, Oracover, etc. Then, depending where the tear is, you might want to remove some of the old covering. For instance if it is between ribs, remove the torn area from rib to rib, then clean the area real good with alcohol or acetone, cut some of the new covering material = seal and shrink. You might be able to get by with buying trim sheet in the same color. That is adhesive and shrinkable also..Good luck.