Spar Replacement Tips???

MikeB · Post by **MikeB** » Mon Apr 24, 2006 17:32

It appears I will have to replace at least one spar on the L16 I just bought (kind of anticipated it). While my AI hasn't had a chance to look at it yet, I can see what looks like a longitudinal crack around four inches long running from a nail hole and outboard from the reinforcement plate for the strut attach point. According to 43.13, the spar can't be spliced that close to the reinforcement plate. The 'crack' shows up on both sides of the spar so I'm pretty sure it's a "crack'

(and I can wiggle it with a adjustable wrench......crude, but works). Not sure how much help my AI will be as he mostly works on spam cans. There is a older fellow like myself about 40 miles up the road who has rebuilt a number of Cubs, Champs, Chiefs, including spar replacement. But like me, he lacks the license. Anyone with wood, tube and fabric experience is getting hard to find in this day and age.

Well, I wanted another project and I got one

!! Be interested in any suggestions or helpful hints on spar replacement. I'll most likely be replacing with wood spars $$$$$ from WAG as I can drive down and trailer them back (about 250 miles).

Thanks,

Mike

high time cub · Post by **high time cub** » Wed Apr 26, 2006 17:35

Mike,

http://www.vintageaircraft.org/informat ... 20303.html

Nathan K. Hammond · Post by **Nathan K. Hammond** » Thu Apr 27, 2006 23:14

Mike, I'm gonna be in the same boat when it comes time to recover. I figure after removing all the fittings, I can pry loose the doublers, and slide the spar out of the wing. I've never tried it on a Champ, but have done it this way on other wings, and it worked real slick like. Once I got the spar out, use it as a pattern for the new one. I'm trying my best to be a cheap SOB, so I'll cut my own spars. Probably have to temporarly install the doublers so they get drilled, then pull the doubler back off. Then install the spar and glue the plates back in place and reassemble.
Think it would work?

nkh

Paul Agaliotis · Post by **Paul Agaliotis** » Thu Apr 27, 2006 23:33

Nathan,
I complete the spar and assemble from both ends.
Paul

Nathan K. Hammond · Post by **Nathan K. Hammond** » Thu Apr 27, 2006 23:50

Paul,

I agree, but that only works if you're replacing both spars, and the leading edge or have the whole thing drilled apart or what ever reason.

nkh

Paul Agaliotis · Post by **Paul Agaliotis** » Fri Apr 28, 2006 00:19

I build my wings on a table, not saw horses, and it,s no problem to pull a
single spar from the wing. It comes apart nicely at the aileron well and one leading edge section. Once apart the inboard or outboard section can be removed easily as a unit.
I dont feel a proper glue joint can be made at the doubler plate with the wing assembled.
Paul

Nathan K. Hammond · Post by **Nathan K. Hammond** » Fri Apr 28, 2006 01:53

It comes apart nicely at the aileron well and one leading edge section.

Now thats a slick idea! Thanks for the info.

nkh

David Johnson · Post by **David Johnson** » Fri Apr 28, 2006 06:02

Guys, be very carefull using the old spar as a pattern. You will get very close, but the wood in the old spar makes a poor drill guide. When you try to assemble fittings you will find any misalignment. You want to be able to push the bolts in fittings without a hammer....I used an old spar to make a drill jig with hardened drill bushings. First, I clamped a large drill block over a hole using a piece of drill stock as a line up pin. Then changed the drill bushing in the block to drill for the OD of the bushing going in the hole. Then glued the bushing in the hole with T88. Works pretty good if used with a drill press. For the strut attach doubler, remove it from one side(nearest your new spar). Then use a router to relieve the drill jig spar enough for the spars to fit together flush. We made a special jig for the drag/anti drag wires. You have to be carefull here too. The jig is a lot of work, but the up side is you can use it over and over. Some folks may say overkill, but I don't like to worry about spars when I am out playing. Hope this helps a little, we have been thru building Champ wings several times. David Johnson
Laughing

David Johnson · Post by **David Johnson** » Fri Apr 28, 2006 06:07

Please disregard the laughing comment at the end of my last post. Very serious subject. I was playing with the emoticons and did not get it all deleted before sending the post. Should not turn rednecks loose with computers with out training (or planes either) HeHe. PS Nathan, we have a mutual friend, Derek L., I want get down and meet all of you sometime, David J.

MikeB · Post by **MikeB** » Fri Apr 28, 2006 09:02

Thanks for the comments, guys. I'll take any and all tips and sort out what works best for me. I've been eye balling the job for a few days, but just put the wings up in a rack in the shop until I get around to working on them, probably next winter. Going to do the fuselage and control surfaces first to open up the shop (24 x 32) a bit. Between my brother, who is an excellent wood worker and machinist and myself (who is a wood butcher) we could probably build the spars, but we're so far from a source of spar material that it almost seems more practical to order new spars from Wag-Aero ($666 each right now) and drive down and pick them up. Paul, do you have any idea of the cost involved when you build your own spars...not including trucking, etc?? I'm not cheap, but I want to get the job done too.....before I'm too old to fly it. Although the building and restoration is almost as much fun as flying to me.

Thanks,
Mike

(Hard at work on the L16 and going out to buy a bead cleaner today)

Paul Agaliotis · Post by **Paul Agaliotis** » Sun Apr 30, 2006 16:37

Mike,
I buy 1"x 12" blanks between 18 and 20 Feet long. The cost of each blank is about $300. The 12" plank allows you to get 2 rear spars from each board. The shipping on this type of load is out of this world. It costs as much to ship as it does to buy!
I get my wood from Aircraft Spruce and Specialty in Corona CA. They have allowed me to select my own wood as long as I restack what I disturb. The mill worker at the store is also very good at selection, don,t be afraid to have him select the wood for you.
If you can buy the spars at $666 thats not too bad. It takes about 5 hours to make each spar.
Paul

high time cub · Post by **high time cub** » Mon May 01, 2006 08:59

http://www.mccormicklumber.com/sitka-spruce.htm