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Horizontal stabilizer bracket 8-3 AA6 aluminum issue

fdeppieri

Member
Hi all,

I?m building the couple of brackets related to the Horizontal Stabilizer, starting from aluminium AA6 187x2x2-1/2 as reported in the RV-10 8-3 plan.

The result of the work I did is satisfactory, but the issue is in the original aluminium bar.

I?m a little bit concerned that the original AA6 aluminium bar is not ortogonal; the faces that should keep an angle of 90 deg are affected by an error grater than 5 deg.

Are there anybody with similar experience?

Because the brackets hold the Horizontal stabilizer, this gap could create some out of control strenght.

Thanks a lot
Francesco
 
It's hard to imagine that stock being that far out of true (5+ degrees is visibly off) but if it is then you need to get it replaced. Do not try to bend it because you might induce internal stresses or cracking in a part that you definitely don't want to fail. I have to say that the stock I received in my kit was just fine, but that was 10 years ago.
 
I received similar out of ?square? stock on my 3 build. Van?s replaced it and the bad stuff went into my scrap pile.
 
Thanks a lot!

I already wrote to Vans waiting for an answer.
I double checked the bar, and it is out of square natively. Very bad item.

Francesco
 
Hi,

I received a very strange official answer from Vans. It reports exactly:

".... The mill specs for that angle are pretty broad ? it is often not exactly 90 degrees as we receive it from the supplier. If you wish, you can open the angle up slightly by squeezing it in a vice (padded with wood), but it is not critical and would be OK as it is when bolted down to the fuselage later."

I'm very worried about: more than 5 degrees that can be seen by eye and it is too much for anything.

I ordered a new aluminium bar...

Francesco
 
off as well

Mine were a bit less than 90deg thus the trailing edge was the only part making contact on the spacers. I was worried about the spacers walking around while drilling. I too contacted Van's support and they said that I could attempt to open up the bend in the angle some but since it was already riveted to the HS spar that I would need to block the spar so as not to bend the spar web.

I made some wood blocks to support the spar web and used a large crescent wrench to open the angle some. I did not feel comfortable applying enough force with the wrench to open the angle up all that much. It was a bit better after the exercise but not worth the hassle.

Turns out that carpet tape is thick enough that it filled the void reasonably between the spacers and the angle and drilling the bolt holes was a non issue. Once bolted down everything mates up fine without any gaps between the spacers and the HS attach brackets. Torqueing the bolts down closed the gaps easily without using anything other than normal torque.
 
Hi,

I decided to proceed ordering a new aluminium bar; if the new one is better I will proceed to rebuild the brackets.

In any case, I have to thank Vans for prompt response and because it offered to deliver a new bar (despite it can not assure the new is better).

Thanks
Francesco
 
How did each of you resolve this? Did ordering a new piece of AA fix the problem? Mine appears to be ~1.5deg less than square (~1/32? gap/deflection at the 3/16 bolt holes).

Vans recommended the socket/vise technique. Not having any luck spreading the angle that way. Believe it would work if the part was not so thick.
 
Hi Brandon,
Vans sent me a new aluminium bar much better than the older.
1.5 degree is the out of square value of the newest.
Becuse I do not like to force it to 90 deg, I decided to keep it as it is, postponing the perfect setting during the empennage assembly.
I think it is possible to adjust it using a different height in the matter placed between.

Francesco
 
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