AN3H-17A Bolt orientation on RV7 aileron bellcrank

[elorozco1]

I am building an RV7A, and I've just drilled my aileron bellcrank for the roll servo pushrod.

Using the orientation shown in the installation drawings, I can't seem to figure out how to put in the AN3H-17A bolt in the hole I drilled in the bellcrank (i.e., with the head facing the top of the wing).

Unless I severely enlarge the hole in the aileron bellcrank, the bolt is too long to insert from the top, as the 'middle' plate of the bellcrank (the one with the lightening hole in it) interferes with the bolt going in straight.

The 'easy' solution here would be to insert the bolt from the other side (i.e., head down, nut facing the top of the wing)

I've searched this forum and don't see this question coming up, so I am either missing something major, or people are just putting in the bolt 'upside down' ??

Thanks!

Luis Orozco

 

[jbrady]

Re: AN3H-17A Bolt orientation on RV7 aileron bellc

Luis did not get a reply to his question since January.  I have exactly the same issue on our RV-8.  I just drilled the aileron bellcrank to #11 as per instructions to take the AN3H-17A bolt that attaches the servo arm. But the 1 7/8 inch bolt won't go in the hole because the other leg of the bellcrank that supports the aileron pushrod gets in the way.  I am not keen on making the hole oversize or oval to overcome this.  The bolt will go in the other way round but the the bellcrank arm is only just on the shank of the bolt which is not ideal.  It may be possible to rearrange the washer sequence which would help.

Please can Dynon support advise.  A diagram of the issue is on my blog  http://gruvebuildlog.blogspot.com/.

John

 

[dynonsupport]

Re: AN3H-17A Bolt orientation on RV7 aileron bellc

Many folks pre-install the bolt while they have the bell crank plates apart. Since you're past that, you can loosen the top bolt to separate the plates and rotate them apart to get the clearance you need to insert it from the right direction, or, less optimally, you can opt to install the bolt from the other side.

 

[jbrady]

Re: AN3H-17A Bolt orientation on RV7 aileron bellc

Thanks for that but the state of assembly has no impact on this and I have all the components in my bench just now with nothing assembled.  The problem is not with the bellcrank attachment brackets but with the bellcrank itself which is a single welded component as depicted on the Dynon drawings.  The bolt concerned is not the bellcrank pivot bolt but the AN3H-17A supplied by Dynon to attach the servo arm bearing and spacer assembly to the hole that the Dynon instructions say must be drilled in the bellcrank arm.

The Dynon instructions require the bolt to be inserted downwards through the hole that has to be drilled in the lower arm of the bellcrank but that is not possible as the upper arm of the bellcrank prevents a bolt of this length being inserted in a hole in that position.

Please see the picture depicting this on my blog as linked from my previous post.

If you say that this bolt must be inserted the other way round, please provide instructions on the sequence of washers and confirm that the shank of the bolt is adequate to engage in the bellcrank and provide the required structural integrity.

Kind Regards,

John  

 

[dynonsupport]

Re: AN3H-17A Bolt orientation on RV7 aileron bellc

We might have something wrong here, but, we thought that the lower arm plate (the one we ask you to drill a hole in) isn't welded to the upper bell crank plate (the large triangular one with a big hole in it).  We thought that these plates were separated by spacers, and therefore could be loosened and rotated without issue.  If the spacers are indeed welded to the upper and lower plates, it would be impossible to get the bolt in the orientation we have asked without making the bolt hole slightly larger or oval. Bottom line is if you cannot get the bolt in the direction we have specified, it is ok to install the bolt upside down using the same washer/spacer stack up. We do have evidence that customers have done it both ways. Attached are a couple of pics.

 

[jbrady]

Re: AN3H-17A Bolt orientation on RV7 aileron bellc

Thanks that is helpful. The bellcrank is indeed a single welded component. I find if I put the bolt in the other way around, the fit into the bellcrank arm is on the taper between the threads and the shank so the bolt does not locate to a close tolerance. I have ordered longer shank bolts; AN-20A which is 1/8 longer and A102-15D which is an equivalent british bolt which is 0.050 inches longer in the shank. I will post when I see which one fits best.

Thanks again

John