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Anti Servo Tab Assembly hinge misaligned

N

ntolman

I'm New Here
This is the first experience for me building an aircraft and have been working on the RV12 since January. I am in the process of putting the empennage pieces together. While placing the anti-servo trim assemblies I noticed that the hinges on the right side do not align. I am not sure what went wrong here. I have drilled the hinges as per the guide. When I set them side by side it definitely shows one hinge placed slightly different than the other.

Has anyone experiences this also? Any recommendations for a fix? I thought I may just need to order another assembly for the right side, but I wanted some feedback before I do that.

Photos from various angles are below. Thanks.


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It's been a while since I did my ASTs but I didn't have an alignment problem like that. It looks like, in your first picture, that the top hinge half on the right side is attached farther from the (vertical) joint than the top hinge half on the left side. It looks like that's causing the misalignment. If that's the case (and not just an optical illusion in the photo) maybe you can remove the rivets from the top half of the hinge and just get a new hinge. Maybe that's what you meant when you said you might order another assembly?
 
Read THIS THREAD about hinges. And post 9 of that thread has links to hints for building the RV-12 that might be useful. Always cut hinges 1/2" longer than the plans call for. Study the plans, then cut the hinge barrel off from the correct end.
 
Mich48041 said:
Read THIS THREAD about hinges. And post 9 of that thread has links to hints for building the RV-12 that might be useful. Always cut hinges 1/2" longer than the plans call for. Study the plans, then cut the hinge barrel off from the correct end.
Click to expand...

This is not his problem. Seems the fella miss located a hinge leaf holes "slightly".
 
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Have you riveted the other hinge halves to the back of the stabilator yet? If so, check the AST fit first before deciding what to do. If not, then you can probably make any necessary adjustment there. You don't seem to be very far off the mark - maybe 1/16"?.
 
Thanks for the responses. I went back and check the hole template guide. Interestingly I noticed that when placed on one side the holes line up with the rivets (as seen in first photo), but when turned over the holes do not align (as seen in second photo). This may be the cause of the small discrepancy. I will order new hinges, re-drill and see if that solves the problems.

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BigJohn said:
Ntolman, welcome to the forum. Your top picture seems to show a gap between the ends of the two sections, and by eyeball looks to be about the distance your hinge strip is misaligned. Suggest you double check the countersinking and flush riveting of the control horns where they attach to the structure and touch each other.

See this linkhttp://www.mykitlog.com/users/display_log.php?user=BigJohn&project=639&category=4221&log=68861&row=30 for description of my similar problem back in 2009.
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I think that's a big part of the problem.
I had a similar problem. I redid my control horns which closed the gap and was able to get the AST's installed.

Jim
 
Don't feel bad. I screwed up most of the hinges on my build. You have to really, really read the instructions and focus. I bought a lot of extra hinges from ACS to have on hand. And this was my 6th build......go figure.
 
Drill templet/guide?

Is your drill templet bad?

As I recall, Flipping the drill templet/guide while keeping the templet's reference notches correct should not make a difference, and in your photos it does.

Just a thought.

-Dave
 
Jim T said:
I think that's a big part of the problem.
I had a similar problem. I redid my control horns which closed the gap and was able to get the AST's installed.

Jim
Click to expand...

I can almost guarantee that the problem is in the horn attachment, not the hinge alignment. What happens is that it is very difficult to clamp the horn to the end of the AST tight enough to prevent the rivet expanding between the pieces as you squeeze it. That expansion is very small, but enough to hold the two pieces slightly apart, resulting in the gap we see in your top picture. On my second attempt I riveted the horn to the end piece BEFORE installing the end piece into the structure. That made it easy to properly clamp the pieces and get a good tight rivet set. Please look into this possibility before you make a lot more work for yourself by drilling out the hinge strip.
 
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I picked up a replacement hinge on Friday and spent this evening redrilling the hinge and attaching to the right AST assembly. As in post #7 the hinge template I was using was not the same when flipped over. I made sure when I drilled this time that it would move the hinge over the 1/8 inch or so that was required. I was then able to attached the right AST assembly and bolt them together.

Another issue as arisen and I don't know if anyone else has had this issue. When I have the left AST assembly even with the stabilator the end of the right AST assembly is about 1/2 inch lower than the stabilator. And therefore, when the right AST assembly is even, the left is 1/2 inch lower. Where they join in the middle they are even. Has anyone had this same issue? Any possible remedies? Or is it not that big a deal?

Close up of left AST end.
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Close up of right AST end.
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I'd run it past Vans to be sure but it doesn't sound right. The tabs are control surfaces and I'd want their trailing edges to be in a straight line between each end of the stab. Also hard to see how that could happen unless either the hinges were misaligned or the tabs were warped, both of which seem unlikely.
 
Something is wrong. Seems as though it must have to do with the attachment of the horns, or the placement of the end rib where the horns are attached. Suggest you go back and check those steps.
 
Hinge misaligned, the leading edge of the AST looks too low on the second photo.
 
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I actually had a smaller misalignment than you are showing in the picture and sent my photos to Van's for assistance. Unfortunately I didn't get very useful feedback (generally pleased tech support but on this one I was on my own).

Going over everything I couldn't identify any obvious assembly errors. I then used a digital level on all the different tail surfaces to narrow down the problem. Eventually drilled out the rivets for the right rear HS skin, and reattached it while clamping it in place so that it was better aligned with the AST assembly. Didn't appreciate that even with match drilled parts, there was any ability to slightly adjust where exactly the parts could be riveted in place, but there is in fact some variance especially with the larger components. My fit today is not perfect, might be out 1/8" but it was as good as I could get it. I can only assume that with minor variations in how all the parts rivet together, there can be an accumulation of these deviations and they don't necessarily cancel each other out. I'm not an engineer, but with hundreds of different builders, odds are that not all assemblies will come out exactly the same.

That said, as for the gap in the picture, it appears to me to be a lot more than just an accumulation of minor errors.
 
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