Good day in the shop yesterday. I'm making great progress on the 701 wing repair and starting to see the parts I've been producing come (loosely) together.
With all the parts now made for the fuel tank bay and wing root section repair, it's time to start fitting them in place in preparation for match drilling (and the requisite deburring).
First I decided to drill the rear wing spar doubler/attach bracket. It fits inside the rear wing spar where it attaches to the fuselage. Accuracy here is important so I drew out the location of the rivet pattern followed by using a punch and hammer to gently mark the rivet hole centres. This helps prevent the drill bit from walking across the surfact of the aluminum:
I used the drill press to ensure accuracy, then deburred the holes. This will be back drilled and riveted onto the rear spar once the rear spar is placed on the wing (yet another part to assemble!)
Next I worked on the front wing attach fitting.
Like many things on this salvaged 701, the original builder skimped on this critical piece, opting for a much thinner gauge of aluminum than what is called out in the plans. What made them decide to risk this? I haven't the slightest clue. What I do know is that the correct gauge is substantially more stout:
First thing was to drill the main attach hole. It's critical that this is as accurate as possible to ensure wing alignment and symmetry. First, I measured out the centre of the hole and confirmed that centre using a math set divider:
Using the centre punch mark as a guide, the drill press makes it easy to create a clean and straight mounting bolt hole:
Next was deciding on how to match this new piece to the randomly measured holes in the spar cap made by the original builder while maintaining the integrity of the new spar doubler. Here is the original clecoed infront of the new spar doubler:
I wasn't comfortable back drilling through the spar cap, the spar web, the spar web doubler and the new bracket - just leaves too many layers susceptible to inadvertent damage (read elongated or crooked holes). Besides, without any other holes drilled in the new fittling, how would I attach it accurately?
Next I laughed at myself pretty hard after spending way to much time over analyzing what to do next. I had to figure out a way to drill the new holes so they exactly match the old ones. Should be simple, I'll just put the old and new brackets back to back. Only trouble was that the old one was bent - if I used it this way, there was no way the new holes would be straight:
Now, the answer should have been obvious but bear with me. As the simple answer part of my brain took a break, the overthinker part took over. I'll just bend the old bracket back to flat, that should solve it. Out comes the clamp and two steel bars:
That didn't work. As overthinking brain pondered what to do next, simple answer brain came back from coffee and slapped overthinker in the face. The answer was indeed simple.... invert the pieces! (This is where I started to laugh at myself)
Now the holes in the old piece can be reliably used as a guide to the new holes. I drilled two on the drill press then decided to cleco them together, further ensuring accuracy:
Next I could have gone two ways. I decided to drill out all the holes in the attach bracket on the drill press, instead of doing it while attached on the wing.
With the holes in the new attach bracket now properly matched drilled, I clecoed the new bracket in place on the wing. The it was a simple matter to carefully drill through the spar doubler and the existing holes of the spar web and spar cap:
I'm very happy with my learning curve so far and I'm encouraged that Ron seems pleased with my work.
A large number of the rivets for this part of the wing root and spar assembly are of the solid type instead of the more common pulled rivets used in this aircraft design. As I have no experience "bucking" rivets, Ron suggested practicing on some scrap material first to get the feel for it. Better to spend a few cents on wasted rivets than many dollars on wasting good parts and aluminum!
Up next, learning how to buck rivets.
Huh... just noticed my countdown timer is now less than 1000 days. Better get going!
Husband, father and 911 dispatcher. Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be. First time aircraft builder. Looking to fly my own airplane.