Engine Stand

The snow cooperated to get the engine to the attic. A friend had offered his engine stand but that was just one more thing to carry up to a crowded space. Besides I like inventing things. I have this auto engine stand which I use for the Fly Baby's engine (also a C-85) when it's not on the plane so the plan was to modify it. I had a piece of 3" x 6" x1/4" angle I had used as a second hand bucking some rivets on one of the Cub wings so it seemed perfect for the task. I cut a 2-3/4" hole for the prop hub and drilled 13/32" holes for the prop bolts. On the short side I drilled 2 holes 1/2" dia., 8" apart to mount to the stand. . Leveling it side to side was easy but the stand tips up at a slight angle. I wanted the engine vertical so it would not want to turn and damage anything. I made some wedges from 1/8" aluminum angle, put a taper on one side and left a bit of the flange to get the angle flat. They have a hole in them for the bolt so they can't pop out. I've had those kind of exciting things happen. I also added some washers to move the C.G. forward and strapped a sand bag to the front leg. . . With the come-along hooked to the rafters and a shackle on the lifting lug it was pretty easy to lift the engine into the hole in the stand. I did get the boss lady to help so nothing slipped . The engine is bolted to the angle and we're read to pull the engine back apart. All the machining should be done and it should be just a matter of making sure no rust has developed and oiling all surfaces. I'll also measure everything since I'll be signing for the work.

Flap Hinge Repair

I've removed the hinges from the flaps and cleaned the area to install the new hinges. I need to make a fixture to correctly locate the holes in the new hinge segments so this all fits when the flaps are installed.

Flaps and other things

The new hinge material arrived today to replace all the hinges on the flaps. They are all very bent up from use. It seems better to replace them now. The old hinges are made from AN251-1 piano hinge which is no longer available. AN257-1 is the same except the hinge to hinge pitch has been reduced from 1 1/64" to 1". The extra 1/64" made the loops each 1/2" wide where AN257 loops are slightly less than 1/2" to give clearance between the loops and lengths of hinge in whole inches. It is a nice round number world after all. Otherwise the flaps are in very good condition. Also receive some streamlined tubing to start on the repair of the bent wing strut. The snow is finally melting so I can get the van close enough to the shop to carry the engine to the attic and start taking it back apart to make sure we have not developed any rust and to re-lubricate everything.

Repair Complete

The last task for the new leading edge was to locate the rivet holes on the lower side and rivet it on. When I made the skin the old one measured 14 7/8" but, I made the new 15" because one of the holes was to close to the edge. I should have written it in red on the plastic protector on the skin. I got everything in position and the edge seemed to be in the right place so I aligned the old skin with it and punched the holes. Bad plan, the holes were off by 1/8". In the past I've pulled the skin tight and carefully located 3 holes to align the old skin with before duplicating the holes. . I should have done that here. As a result I removed the new skin and made a new one, again. One thing I did differently was to leave the short (lower) side 3" long and clamp it to the form board. I then pulled the skin around the tube with straps and boards as before and trimmed off the 3" after forming. It made the 2 halves closer in length and much easier to work with. I also made this one using 1" pvc instead of 1-1/4" as I first tried. It fit perfect. . . . . . To match the bottom holes better I clamped the skin down using straps and 2/2's to hold it tight to the ribs. I also found it fit straighter with a block of wood holding the leading edge out at the last rib at the tip. The rib is just not strong enough to pull against and the skin will pull in at the tip and bulge between the ribs along the bottom edge. I had to shim it to a tight fit and the skin came out straight. . . . . . . . . . . Before pulling the skin around I carefully drew centerlines through the holes and made pencil marks on the ribs 1" and 2" from the hole center. This makes it easy to locate the hole centerline parallel to the spar. Once the skin was pulled tight I marked the centerline on a piece of tape at each rib. This made it easy to line up the last holes on the old skin and duplicate the holes as before. . . . . . While riveting the bottom rivets I placed a strap next to each rib to hold the skins tight so all the holes lined up better. All but the rivet closest to the leading edge were able to be squeezed. . . . . . . Installing this new skin went better than the first one, but it was not my goal to get better at this, just get it done. It is done. When the snow finally melts I'll get it outside and finish some light cleaning on the rest of the wing and prime it before covering. I worried that all this work would leave the wing more difficult to trammel but, it was closer to square than the left wing. It also now has the heavier drag wires required by the AD.

Riveting Leading Edge Skin

Between more snow then we've seen in ages and a few days with the flu, I'm a little behind what I had hoped. I found the easiest way to rivet the Leading Edge skin to the Spar aft edge was with my trusty rivet squeezer. The inspection mirror made it easy to see how the shop end formed. Near the compression ribs the skin had to be clamped to hold it tight while riveting because the compression member sits on top of the spar. I had modified the squeezer in the past for repairing Cub ribs and that worked great for getting the tools down close to the spar. The hardest part was remembering that the Spar Flange is not square to the Web so the squeezer handle had to be tipped down to keep it square to the flange. If not held right the rivet would bend and have to be drilled out and start over.

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I found it easier to work this edge with the Leading Edge down. I fitted the drag wires in and adjusted them to hold everything straight. They have to be out to rivet the compression members on the forward side of the Spar.

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Because of the angle of the Spar Flange the rivet on the forward side needed a special bucking bar. I got some 1" x 1/2" steel bar stock at Tractor Supply and made this bar to fit around the ribs over the lower spar flange and provide a surface square to the rivets. The handle allowed me to hold it well even though the mass was a little light. It worked well for both 3/32" and 1/8" rivets on both sides of the ribs. .

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I ground the tip at a 14 degree angle and the 45 degree relief at the top so it would clear the lip of the flange when riveting in the area of the doubler. The tip is radiused and polished.

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The cut out was sawed to a 1-1/2" radius so I could smooth it on the roller end of my belt sander. I screwed the handle on but would have welded it if that were available in my attic shop.

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Everything went well. The 5/32" rivets for the drag wire brackets take a fairly heavy bucking bar about 4 lbs. to form the heads well

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The top surface of the skin is now on and I just have to figure out how to pull it tight to locate the lower rivet holes. I have the feeling I should have bent the Skin more to the finished shape. The drag wires are permanently installed and the wing trammeled per the factory service letter.