Drawings Vs Existing Parts (Spar Holes)

[kyleb]

I was looking through drawings today, making mental notes so I could come up with my game plan for finishing the spars for my Champ. While I was looking at the main wing spar drawing 5-146 I noticed that the hole diameter for the bushings at the wing root is called out as 7/8". That surprised me, because I thought I remembered 3/4" holes on my old (original) spars.

So I went and checked. Yep, the old spars do have 3/4" holes there, not the 7/8" holes called for in the drawing.

So what's a guy to do? Go with what's on the drawing, or build the new spar to match the old one that lasted 60 years?

Also, does anyone know the history of this change in spar hole size?

Thanks,

Kyle

[joea]

Would think about calling Bill Pancake on this one.

[David Johnson]

Kyle, We have the same thing, but have been unable to document why. Citabria wood spars have the 7/8 bushings as well. Looks like the print has a dimension change on it but we can't find the earlier print for reference. Let us know if Bill knows any more. David J.

[kyleb]

I spoke with Bill this evening. His recommendation was to rebuild the wings with the 7/8" holes at the inboard end of the main spar, as shown in the most recent drawing.

He said he'd never seen one with 3/4" holes at the inboard end of the main spar, but that there were numerous changes as the Champ progressed from prototype through the early production models in 1945 and early 1946 (when my airplane was built).

[joea]

If Bill Pancake says it, I would go to the bank with it.

[David Johnson]

Kyle, what prod date and serial do you have? Mine is 7AC-564/1-11-46. First Champ ride was in a plane completed on 4-1-46(April Fools Day). Ours too had 3/4 inch holes. Be Good. David J.

[bigjim]

J.D. HOLBROOK here. Out of the three sets wings i have here! The 45 late champ 10 30 45 had 3/4 holes. The L-16 has 7/8 . the set of early 47 had 7/8 as well. So that pretty mutch says they changed somwhere in between. J.D HOLBROOK WARSAW IN.

[Dennis]

I just checked the old spars I replaced. I was able to slid a 11/16 open end wrench around the bushings in my old spars. MIne is a '46 #1808. Of course they may not be the original spars.

Dennis

[kyleb]

Does anyone have a source for new or used 7/8" phenolic bushings?

I need 6 of the 7/8" dia x 3/4" long w/ a 3/8" center bore.

Also, I need 2 of the 7/8" dia x 3/4" long w/ a 1/4" center bore.

I can't find them in either the Wag or Univair books and material vendors charge a ridiculous amount for phenolic rod (which only sells in 4' lengths, apparently)...

[kyleb]

Kyle, what prod date and serial do you have? Mine is 7AC-564/1-11-46. First Champ ride was in a plane completed on 4-1-46(April Fools Day). Ours too had 3/4 inch holes. Be Good. David J.

David, the Mfg date is March something (don't remember), 1946 and the SN is 7AC-1294. The N-number is N82655.