Bent Longeron At Tail

[OtterlyFoolish]

Ok, here is the one big problem with the Waiex B quick build kit that I just purchased. The original owner told me that it had fallen from a sawhorse and this longeron got slightly bent just at the last 5-6 inches. There appear to be no kinks or fractures visible to the eye but I know that aluminum does not like to be bent and then re-bent. I know that the safest way to handle this is to replace the entire longeron but I am concerned that I may not be able to get each hole in the new longeron aligned perfectly with all the other holes that are already drilled to size. Would that create a bigger structural issue than bending the longeron back? Would it be best to replace each rivet with a larger rivet so that I could final drill all of the holes slightly oversize to accommodate larger rivets?

I have been told that these planes are overengineered and that leaves a part of me that wants to just flex the longeron back to straight and proceed with the build. I certainly do not want to get myself or anyone else hurt so I need some real advice from seasoned builders. Hopefully with some science to back up those opinions.

I am fine with putting in the work but any advice as to how to approach this properly would be very helpful.

[n307tw]

I would try and bend it back a little but not excessive. The aluminum supports in the rear will absolutely force that longeron in place. I wouldn't personally replace it. Wait and see what others say also.

[GraemeSmith]

I'm not going to comment about the advisability of bending it back.....

But you will always know...... Can you live with that? :-)

[Bryan Cotton]

I'd bend it back. Does not look like a huge yield happened. Can you cleco all the other parts to it and spring it to shape without bending it back?

Beyond the opinions of me and the rest of the peanut gallery, email/call Sonex tech support and ask them.

[pappas]

The best thing to do is bite the bullet, drill out the existing rivets, and replace the longeron by simply match drilling through the existing holes in the skins. I use one of these:

https://www.aircraftspruce.com/catalog/ ... m=12-00817

The second option, if you choose, is to rivet the longeron back to the existing skin and bolt it all together. The tail components will likely, I repeat "likely", hold everything in alignment.

Replacing it isn't really that much cost or work. Match drilling is an easy skill to acquire and one you definitely need to have. You will use the tool above often and it will keep you from oversizing any rivet holes you need to drill out.

[Bryan Cotton]

Replacing it isn't really that much cost or work. Match drilling is an easy skill to acquire and one you definitely need to have. You will use the tool above often and it will keep you from oversizing any rivet holes you need to drill out.

Lou is right - It's not hard or that much of an expense. Those would be easy rivets to drill out as they are backed up by the relatively solid longeron. The only tools I use are a nice sharp cobalt drill bit and vise grips. I don't think you will need the vise grips with the rivet through the 1/8" thick longeron. The hole in the middle of the rivet keeps the bit centered well enough, especially if you pop out the mandrel first.

[OtterlyFoolish]

Thanks for the feedback guys. I asked Kerry when I was at Oshkosh this summer and he said he would replace it but that was without even seeing the pictures. That is obviously the safest thing to do but I feel that he is probably required to say that due to the liability involved. That is why I am asking real world builders here and on the SonexBuilders forum. I am still considering a new longeron but the match drilling will be a chore seeing how you can not just lay the old longeron on top of the old one for accuracy. If there was an actual bend point or any visible fatigue I would not hesitate to replace it but it appears to be minor in my eyes. That is why I want the opinions of those with experience.

[Bryan Cotton]

If I was going to match drill it, I'd clamp the new longeron to the skin and just transfer the holes. If you really wanted to be crazy about it, transfer the holes from the bent longeron to some cheap home depot 1/8" flat stock, and then transfer those holes to the new longeron.

There is nothing wrong with being crazy about it, but it is probably not a requirement.

[OtterlyFoolish]

If I was going to match drill it, I'd clamp the new longeron to the skin and just transfer the holes. If you really wanted to be crazy about it, transfer the holes from the bent longeron to some cheap home depot 1/8" flat stock, and then transfer those holes to the new longeron.

There is nothing wrong with being crazy about it, but it is probably not a requirement.

That is a simple and practical solution to the match drilling. Kinda mad that I did not think of it myself.

Thanks,
Marc

[Blank]

I just finished replacing both upper rear longerons in my legacy kit due to the previous builder completely botching the horizontal stab install...among other things. Kerry was key in pushing my to do it. It was labor-intensive but I'm very satisfied with the end result. I purchased the 1" angle of 6061-T6 locally and saved a ton on shipping cost. Feel free to get in touch with me as I have many photos of the removal and re-install process.

Craig