New spars

[Dalton]

Looking fo advice on rebuilding a set of wings. What is the thought on the ribs, should they be taken apart at the riveted joints and reassembled at the spars, or left in one piece and slid onto the new spars? I'm only familiar with rebuilding Aeronca wings

[astjp2]

I slid mine one, but I had truss ribs, just make sure to file the nail hole jagged edges smooth before you do. Tape on top and bottom edges will prevent some scratches. Tim

[N96337]

Yup, squeeze the nail holes flat, then I put a chunk of tape on the rib face and slide it on.
John

[taylorukuk]

We have just made 4 new spars and we have left it in one piece to slide in the new spars - Looks the easiest way.

[3Dreaming]

We have just made 4 new spars and we have left it in one piece to slide in the new spars - Looks the easiest way.

Have you done it yet? Having the ply reinforcement at the wing strut attach area makes that portion of the spar thicker. Because of this it normally doesn't want to slide through the narrower ribs.

[taylorukuk]

We have done it - We removed the rivets on the top portion of the ribs to open it up a little then slid the old spar out - New ones will be fitted next week.

[Scott]

Kind of depends on how tight the ribs are on the spars. Differences in spar dimensions and varnish make a difference.

When all is said and done, deriveting ensures your new spars won't be all scratched up, without adding significant work (on a net basis).

Also this enables you to install the compression struts first during assembly, which just makes things more behaived lol.

A hand rivet squeezer makes easy work of the installation.

https://1.bp.blogspot.com/-bWuy9VChBFE/WV8RM5aDoAI/AAAAAAAADi8/cyBvYqPnlQcMd-qy4-XaFJJJv7vrLOdWwCLcBGAs/s1600/DSCN5512.JPG

[astjp2]

Have you done it yet? Having the ply reinforcement at the wing strut attach area makes that portion of the spar thicker. Because of this it normally doesn't want to slide through the narrower ribs.

Why yes I have, the truss ribs have to slide over the root plys and the strut reinforcements are larger and the ribs accommodate it

[JohnGreggJr]

I’m new to this forum. We are in the process of restoring a 1946 BC12-D. We are working on the wings right now; we have post-war stamped ribs. This past fall, we purchased a new set of FAA PMA spars from Wag Aero. PN: BA87DF (front) and BA88DF (rear). We have Safe Air Repair Drawing R-A87 Rev. AD, dated 6-11-96, which the spars are manufactured to.

Including the airplane we are restoring, we have post war stamped rib wings from 3 ea. aircraft. Two sets of wings are being used for parts.

The PMA spars arrived to our shop in Phoenix, Arizona from Wisconsin in excellent condition. However, the above print shows the 5 ea. front spar holes for the lift struts to be 3/8 in. (.375”), and are to take “fibre bushing” (I believe) PN: B-820 (hard to make out PN on drawing). The print also references “For Front Spar see 2570”, which is the prime number callout for various bushings. We do not have drawing 2570.

All six of our as-removed front spars have .462” holes in the lift strut attachment area, and all are bushed. Since we have samples of 6 ea. front spars from three different aircraft, from different areas of the US, and all are identical, it is plain to me that the front spars in the field have .462” lift strut holes. Does someone have technical data that calls out for the .462” holes, rather than the 3/8” (.375”) holes referenced in the print?

[3Dreaming]

You are putting to much thought into this. Either get or make bushings for the holes you have, or make a fixture and ream the holes to match the bushings from the old wings. They seem to have made changes like this at the factory all of the time.

[Robert Lees]

I'm new to this forum.....

Thank goodness for that, John !

(For the avoidance of doubt and in terms of openness, JohnGreggJr and I have been in private email conversations for a few weeks about getting admitted to the Forum...all seems to work now).

It just seems so hard...Bob...Ted....?

Rob

[N96337]

Your old spars had been modified for the gross weight increase to 1500 lbs, by the Harer STC. That's where the 11/16 bushings are used. Either that, or they came from a model 19. It wont hurt anything to incorporate that at the time of rebuild and will definitely save some work if you ever want to install that STC.
John

[astjp2]

Or the pre 1956 337 that’s approved data for the 85 and gross weight increase. Hence no stc required!

[Scott]

The gross weight STC calls for larger bushings. I don't recall the exact dimension but its more like .750".

The OEM spars had bushings on the front spar at the root and lift strut fittings. .462 sounds right for the root, the ones at the lift strut are smaller.

[taylorukuk]

I would incorporate the STC mod with bigger bushings (we are currently having the bushes made in ali - cost us "£5 each completed)