Repairing a Broken Leading Edge
Step 1. First things first—you have to be able to see the damage. This will involve removing the covering material so that you can see exactly what is busted. Be light with your knife here; don’t cut deeply into the covering and damage the balsa sheeting underneath. Using a heat gun or heat iron on the covering will help it come up easier.
Step 2. Now that you can see the damaged area, you need to remove the sheeting around it. To make straight cuts, use a straightedge to guide your hobby knife. When the sheeting is removed, you’ll be able to see if there are any internal parts that need replacing.
Step 3. On this wing, we needed to replace the leading edge (LE) and part of the rib. By notching out the old LE past the repair opening, you can get a solid glue joint on the new LE. Using a good sharp razor saw will make quick work of this joint cutting.
Step 4. Here, you can see the replacement LE has been fitted snugly into place. It is always best to have all replacement parts fit snugly into place for a good glue joint. Now you can trace a replacement rib from the undamaged rib next to the damaged one. This will be the best way to reproduce the same replacement rib. Once the part is cut to shape, place it against the damaged one, and make sure everything fits before applying the glue.
Step 5. Tack-glue the parts into place first, then lightly flow thin CA into the cracks and seams to make sure everything is secure. Before replacing the top and bottom wing sheeting, you will need to add some doubler strips under the edges of the undamaged sheeting so that the replacement sheeting has something to adhere to. Another good idea is to glue some doublers to the side of the ribs to form a strong base support for the ends of the new sheeting.
Step 6. The new sheeting has been glued in place, but before closing up the bottom of the wing, reglue all the inside seams of the top sheeting. This will ensure that you have a strong bond everywhere. Add the rest of the sheeting, and let everything dry.
Step 7. Using medium-grit sandpaper on a bar, start removing material from the leading edge. Then, using fine sandpaper, shape and sand everything flush and smooth. Next, start filling all the seams with a lightweight spackling compound. To make the filler easier to apply, use a damp sponge to lightly moisten the wood around the repair area. Press the filler firmly into all the seams and dents, and let this all dry. Use 220-grit sandpaper, sand everything so that it is level and smooth. Wipe and clean all the dust off the model.
Step 8. Cut the matching covering to usable lengths, and use some rubbing alcohol to degrease the covering around the repair. Cut the covering about 1 inch larger than the repair area so that it overlaps the existing covering. Apply the covering using the heat gun set to low, and start working from the center of the repair out to the edge. This will help prevent any air bubbles from forming under the covering. Go back over the covering using a higher heat setting, making sure to seal the edges well. Apply any trim covering using this same method, being careful not to create air bubbles between the coverings. Be sure to seal down all the edges securely, and while you are at it, check all the other edges and covering seams on the model and iron them down as well.
FINAL THOUGHTS
Don’t look now, but you have the skills to make many repairs that may come along as you continue your flying career. The best part is that they are easy and fun to do, plus they can save you some big money, which you can spend instead on new planes and accessories!