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  • L-2 wing rebuild

    Get ready for a long post.
    The fabric on the wings of my L-2B was getting to look pretty bad, fading, cracking, ringworm etc. so I decided it was time for a recover. When I removed the old fabric I discovered, to my chagrin, some serious issues with the wood. Although the airplane has been hangared for the 20+ years that I have owned it, and was told that it had been hangared by the previous owner, it looks like moisture took its toll on the wood and the glue. Gravity lets any moisture in the wings collect at the trailing edge and that's where most of the damage was, especially at the inboard section of the aileron bay. and all along the aileron bay itself. This is an area behind the rear spar where there are no inspection covers and along with the area forward of the front spar don't get inspected during the annual inspection. It appeared to me that when the last recover job was done, a lot of sins were covered up. My speculation. A big warning to L-2 inspectors is to look for scalloping along the trailing edge of the wing. These wings had the wood trailing edge inboard of the aileron replace with metal and were straight as an arrow.

    Time for a major rebuild.
    I do not have the skills, tools (I don't even have a table saw or a chop saw), or enough time left in my life ( I'm 76) to undertake this project. I have scoured the state of Alaska for anyone capable of doing this kind of work. I found only two who I believe have the ability to do the job and neither have enough time left in their lives either to undertake my project and do all the other stuff that they plan on doing. I built a 17ft crate and packed up the wings and shipped them to my friend Tim Boughner of Tim's Aircraft in Port Orchard, Washington. Tim has the experience since he has rebuilt Stearman wings and L-5 wings. Being a one man shop, he is very busy and really doesn't have the time for my project but he said that if I came down and help him he would try to do the job when he could spare some time for it. I guess now he doesn't have a choice since my wings are cluttering up his shop. I know that a lot of people start down the road to wood wing restoration by making the ribs. Taylorcraft ribs are easy to make as they are all basically the same and there are a lot of them. Just make up a breadboard and pop out a batch every day and eventually you have a bunch of ribs that all look alike. Now comes the hard, time consuming part. Installing and gluing ribs is a time consuming and tedious job. Sanding of parts is not allowed and resorcinol glue is the only approved glue and can be difficult to work with. The real challenge is making the formed plywood leading and trailing edges.
    I asked Tim if we could use metal instead wood for everything except for the spars like the B series Taylorcraft, after all, they have the same airfoil. I bought a BC12 wing from a bone yard to compare the two. They are identical to the L2 with the exception that the L-2 has a thicker front spar, one size larger tube on the compression struts and one size larger drag wires. B series ribs would have to be modified to fit the thicker front spar but other than that everything is the same.
    Tim is a master at getting field approvals. He has a very good relationship with his PMI and presents things to the FAA in a way that they can understand it and approve the project. I asked him what he thought about getting a field approval for my idea and he said that it was very possible. We made a mock up section of the L-2 spars and put a modified B series rib on it with a D series wood rib next to it and made a presentation to the FAA. Yesterday the FAA gave us the go ahead with the mod. They are calling it basically a material substitution.
    This L-2 is a survivor. It has never been a hangar queen or a back of the hangar restoration project. The cost of shop labor to make new wings in today's environment would be prohibitive and exceed it's value. It deserves to live on and bring the pure joy of flying to more generations for the next 76 years. There is nothing on earth greater than having a throttle in you left hand, a stick in your right hand, and watching the golden sun reflecting on the back of a wooden propeller.

    Bob Picard
    Bob Picard
    N48923 L-2B Skis/Wheels
    N6346M Stinson 108-3 Floats/Skis/Wheels
    Anchor Point, Alaska TF#254

  • #2
    Bob,

    I think everybody on board agrees with your sentiments. Good luck with your rebuild and, as always, keep us posted.

    Peter

    Comment


    • #3
      Interesting approach. Are you trying to us prewar rib, or stamped ribs? No reason why it won't work. The DC65 actually used metal spars and built up metal ribs.

      Comment


      • #4
        So what about the wing that needs rebuilding? Understood about time and such, but maybe leave the wing somewhere with notes so maybe someday it can go back to it's fuselage?
        Ryan Short, CFI, Aerial Photographer
        Former Taylorcraft BC-12D owner - hopefully future owner as well.
        KRBD and KGPM - Dallas, TX
        TexasTailwheel.com

        Comment


        • #5
          Originally posted by Ragwing nut View Post
          Interesting approach. Are you trying to us prewar rib, or stamped ribs? No reason why it won't work. The DC65 actually used metal spars and built up metal ribs.
          Ragwing,

          Pre-war ribs are not built in a manner that makes them suitable for the modification required to attach them to the thicker front spar. Besides, I think it would be nearly impossible to find enough of them in good condition to do two complete wings. Actually, we made our presentation to the FAA using D&E Aircraft stamped "experimental" ribs. Since new Taylorcraft ribs are no longer available and the supply of good used ribs without damage is unknown, we elected to use the D&E ribs. We are not locked in to the D&E ribs yet and have not ordered our supply of them. If we can find Taylorcraft stamped ribs in good condition we may go that way. With new ribs without the usually damaged holes for the wires we will be able to use pop rivets to fasten the fabric. If I read this forum correctly, finding the right wire for the T-Craft ribs seems to be a problem as well. On the other hand, Taylorcraft ribs will be easier to modify. Since the rear spar being the same dimension as the B series, only the front part of the rib needs to be modified. We weighed the different ribs and found the D&E ribs only 2 grams heavier than the wood ribs, adding about 2 lbs to the wings. The Taylorcraft ribs, weighed less than the wood ribs they replace and reduce the weight by 5 lbs. The difference is that the D&E ribs are made of .025 aluminum and the Taylorcraft ribs are made of ,020. With the leading and trailing edges being made of aluminum we figure that the wings will weigh about the same as the all wood wings, perhaps slightly lighter.

          Bob Picard
          Bob Picard
          N48923 L-2B Skis/Wheels
          N6346M Stinson 108-3 Floats/Skis/Wheels
          Anchor Point, Alaska TF#254

          Comment


          • #6
            Originally posted by RyanShort1 View Post
            So what about the wing that needs rebuilding? Understood about time and such, but maybe leave the wing somewhere with notes so maybe someday it can go back to it's fuselage?
            Ryan,

            We are not replacing the wings, just the ribs and leading and trailing edges with aluminum instead of wood. We are using the same spars and all other hardware. Nothing here to really save.

            Bob Picard
            Bob Picard
            N48923 L-2B Skis/Wheels
            N6346M Stinson 108-3 Floats/Skis/Wheels
            Anchor Point, Alaska TF#254

            Comment


            • #7
              Click image for larger version

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ID:	186263 Well I finally figured out how to make the pictures small enough to attach to these postings. These pictures show how we made a mock-up section of the L-2 wing section using two L-2 compression struts (which are larger in diameter and shorter in length than the BC series airplanes) and two sample spar sections representing the L-2 front and rear spars. We then installed the wood and metal ribs side-by-side for comparison. We made our presentation to the FAA inspector and he gave us the go ahead on the basis of what we showed him.

              Bob Picard




              Bob Picard
              N48923 L-2B Skis/Wheels
              N6346M Stinson 108-3 Floats/Skis/Wheels
              Anchor Point, Alaska TF#254

              Comment


              • #8
                To continue the saga, I just flew back from Seattle where I spent 5 days with Tim in his shop working on the wing project. We dismantled the left wing as we are only doing one wing at a time so we can refer to the intact wing should the need arise. We discovered a few interesting things when dismantling the wing. The first thing we noted is the that the left and right wings are different (other than being left and right of course). The left wing is from an L-2M and the right wing is from an L-2B.
                Indeed, as suspected before, there were a few sins that a previous rebuilder had hidden under the fabric. In addition to severely rotted wood all along the trailing edge we found a spar crack at the jury strut fitting attachment hole that had been covered with a scab patch. The spar was made with a laminated plank and the crack only appeared at the front portion of the lamination. Once the leading edge (which wraps all the way around the top and bottom of the spar) was installed, it was impossible to see the scab patch, which was improperly glued by the way, without removing the leading edge. The visible back part showed no crack of course. I will try to post a picture in a subsequent post.

                Bob Picard

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                Bob Picard
                N48923 L-2B Skis/Wheels
                N6346M Stinson 108-3 Floats/Skis/Wheels
                Anchor Point, Alaska TF#254

                Comment


                • #9
                  Click image for larger version  Name:	L2 rib8.jpg Views:	0 Size:	138.2 KB ID:	186536Click image for larger version  Name:	L2 rib9.jpg Views:	0 Size:	159.3 KB ID:	186537 Just returned from Tim's shop near Seattle and it's time for an update. We went to Port Townsend to get wood for a new spar. They had a nice stock of beautiful air dried spruce of the quality required to make a new spar from. They sell it by the slab that they have already cut, they didn't want small chunks or pieces laying around that they can't get rid of, so I had to buy the whole thing. The bad news is that I had to buy a piece 4 1/2" thick 6" wide and 17 1/2 feet long. The good news is that here is enough material to make two spars should the other still assembled wing offer a surprise as well. If not, I'm sure I will not have a difficult time finding a buyer. I will also be selling the serviceable BC 12 spars that I have removed from the wing that I purchased and dismantled when I wanted to know exactly what the differences are between the BC12 and L-2 wings and what would fit and what wouldn't. Tim called me this morning and told me that the millworks had called and that the spar material has been dimensioned and is ready for pick-up.
                  We received our order from D&E Aircraft and I have never seen anything so well packaged for shipping. That guy knows how to package stuff for shipping. The new ribs are beautiful. We made a "breadboard" fixture using an original wood rib so we could modify the D&E ribs to match the L-2 ribs exactly and assure repeatability for all the ribs. We actually made two fixtures one for left facing and one for right facing ribs. It's a lot of work modifying each of the 26 ribs but the fixture made the process rather easy if not tedious. While doing the rib modifications Tim's FAA PMI came by to check on our progress. He liked what we were doing and told Tim to write up a 337 and send it to him for approval.
                  Last edited by n6346m; 3 weeks ago.
                  Bob Picard
                  N48923 L-2B Skis/Wheels
                  N6346M Stinson 108-3 Floats/Skis/Wheels
                  Anchor Point, Alaska TF#254

                  Comment

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