Advice sought

Nev

Nev

Quick-build 4-place B #25
Seeking advice on two points.

I’ve made an error when drilling rivet holes for one of the inspection port frames, resulting in one row of holes being very close to the edge. I’m thinking to put several more rivets in between, but further from the edge to provide more integrity. It should give 4x rivet diameter spacing. Is this a safe way to resolve it ?

Click image for larger version Name: FA64045F-B5DF-46C5-92CF-EA1E7197C9A8.jpeg Views: 73 Size: 205.7 KB ID: 68125

Secondly, is it acceptable to drill and rivet a small stand-off to the main spar, inside a lighting hole ? The rivets would be in the material just outside the lighting hole.

Thanks in advance.
 
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A couple options for the inspection cover holes, one would be like you suggested - add a rivet on either side of the rivets that are too close to the edge (probably not even really necessary but it might make you feel better.) Or just attach the bezel as is and keep an eye on those rivets in the future. Another option would be to increase the size of the inspection hole and start over - that would also require new bezels and covers. It's not something that many will ever notice so it comes down to whether you are going for a functional back country plane or something that will win awards for fit and finish.

Not sure about attaching anything to the spar, I would think it is probably ok but I'll leave that one for someone smarter than me.
 
Nev, you are not the first. There is some relevant advice related to this problem from Mark/Bob on the forum. Look for 56715-wing-access-panel-botch.
 
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geraldmorrissey said:
That's a big hole for a puny inspection point. Make it smaller. Looks like Hulk Hogan could get his hand in there.
Gerry
Patrol #30
Click to expand...

Haha. I'll pass that in to the guy who made it :rolleyes:
Once you get the frame into place it's about right for the XXL glove sized amongst us :p

7C18F12C-92EF-40F1-AF91-C0C1F9DA7EEC.jpeg
 
Personally I would make a bigger panel and make it correct. The wing skin is part of the load bearing structure of the wing. If it were "just" an inspection panel there would be four screws, one for each corner and that would be it. It isn't hard to do and when you get into turbulence you won't be wondering if it's all done right...because it will be done right. I made a bigger one for different reasons. YMMV:

http://www.mykitlog.com/users/display_log.php?user=yeeeha&project=527&category=8690&log=282735&row=5

http://www.mykitlog.com/users/display_log.php?user=yeeeha&project=527&category=8690&log=282736&row=4
 
I thought I could make a "master" inspection cover and match drill them all. Unfortunately they are not all the same. I ended up having to make about half of them over. If the wing is cantelevered, I would agree the inspection covers are structural. With a strut based wing, I am not so sure. I am not the authority.

If they are not structural, you might want to use soft rivets. Regular hard rivets need the edge spacing or you will distort the edges. Soft rivets, not so much, I have used soft rivets for filling a few errant drilled holes and I didn't want to make up a new panel. So far I haven't used one for the requirement that I just suggested.

Stuff like this is hard to research or look up. I have talked to Bob probably half a dozen times in 2.5 years. He knows the answer off the top of his head.
 
There is a thread on kit improvements. One improvement I would definitely do is have the inspection covers, and frames, CNC'ed. I made the assumption they were. I would have them cut, and drilled, CNC. Might even save money on manufacturing.
 
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Thanks everyone for your input. I referenced another thread where Mark had consulted with Bob for the same issue. For my own peace of mind I've added 4 more rivets with spacing exceeding the AC43 requirement. I'll keep an eye on the edges of the existing rivets during inspections.
 
My understanding is that they are considered structural. I consulted my mentoring engineer on this one. He agreed with the advice given in this thread, either make a larger frame, or add additional rivets keeping the spacing IAW AC43.13.
 
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Make it bigger - AC43.13 -
(1) For single row rivets, the EDGE DISTANCE SHOULD NOT BE LESS THAN 2 TIMES THE DIAMETER OF THE RIVET and SPACING SHOULD NOT BE LESS THAN 3 TIMES THE DIAMETER OF THE RIVET.
 
Thanks. But do you mind telling me,(and notwithstanding the AC43.13 requirements) is this the only way to resolve the issue, or just your preferred method?
 
Yes Nev, it would be my preferred method due to the guidance in AC43.13. No, it's not the only way but understand when you ask others for advice it's incumbent on us to provide accepted methods of repair, it would be irresponsible of us to do otherwise. In the end it's your decision of course.
 
Gerhard - thanks very much, that's what I have also been referencing. I will be adding some rivets in this manner on the larger frame where the holes are not so close to the edge, but close enough to that I think it would be prudent to strengthen.
 
Any potential cracks in those holes are already stop drilled, so not much chance of anything going wrong. I am sure some of them will crack through the tiny little ribbons of metal on the edge, but it will not matter.

Personally, I would not be drilling the "main spar web" - even though it's almost certainly going to be fine. Obviously that's the load bearing structure.
 
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My less educated opinion is the same as Battson's. Although I'd bet replacing a rivet with a bolt would be sound enough - its difficult for me to do a good job deburring holes like that so I would worry about it cracking over time. I talked myself out of doing this very thing a few times. It's just too important for me to mess with.
 
I have a small number of rivets s little to close to the edge on 2 frames. I did a little experimenting today on some scrap. The dimpling really messes with the edge. I tried -4 NAS 1097 OOPS rivets, countersinking very slightly instead of dimpling, with much better results. I will put a couple rivets on either side of that rivet with the proper distance. I will probably under squeeze the OOPS rivet.
 
The references I have found in the BH community references using 1/8" rivets for the inspection port ring to wing skin. The info I have seen on sheet metal repair dictate using similar size rivets and spacing for the surrounding structure, which in this case would be 3/32". Are 3/32" adequate for this application?
 
I took this screen shot from Patrol Plans P.2, It shows 3/32" diameter rivets attach the back-up ring for the inspection cover to the wing skin.

Screen Shot 2021-11-17 at 3.06.04 PM.png
 
Thanks. I see that now on my plans also. That explains something else I thought was a problem with the kit parts, which are no longer a problem. My mistake.
 
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