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HS attach issue discovered!

M

MK77

Well Known Member
Hi All,

Here's an issue I just discovered on the RV-7 project that I'm completing. Seems the previous builder broke a drill bit off in the fuselage while trying to drill the holes to attach the HS to the fuse. Looks like he then tried to drill the broken bit out, did more damage and didn't manage to get the bit out in the end. Here's a pic:

https://drive.google.com/file/d/1qu3ZsUofgQRH84WQiZsqQW7EtYQ4Wl-dyg/view?usp=sharing

The hole doesn't go through the longeron but I have no idea how deep the drill bit is embedded. He re-drilled the hole in a new spot, but it's REALLY close to the bend in the angle. No room to get a nylock on, only a metal lock nut. You'd have to grind down a washer to fit. Here's a view from underneath:

https://drive.google.com/file/d/10Qja9C2x00Z7DaibaDowGZpf8cbySTPJiQ/view?usp=sharing

To make matters worse yet, the hole that is drilled isn't exactly perfectly perpendicular and the bolt head is raised on one side when you put it in.

Thoughts?

MK
 
This is a critical structural area, you might want to contact Vans on Monday. I would not leave that drill tip in there. Either drill a punch hole from the inside for a small pin punch or get it out with nitric acid. It won't eat the aluminum, but don't leave it unattended. A drop or two should be plenty. Rinse with mineral free water.

Worth what you paid for it. :cool:
 
An MS21042 nut might be good for close quarters if you decide the longeron is ok.
Larry
 
Hi Matt,

Don't Panic! :p I had a similar issue with an RV-6 I am working on. The previous builder did not drill the holes in the correct location and the bolts did not go through the longhorns. I spoke to Vans and we came up with a solution that other builders have used.

This is a critical area and you want the HS to be securely attached to the longhorn/airframe.

I am going to make some brackets that will allow for a secure attachment. Look at the picture in post #6 of this thread.

http://www.vansairforce.com/community/showthread.php?t=130785

I believe this was a common mistake in some of the early RV-6 kits because there was so much variation in builds before the pre-punched days. The hole to longhorn clearances were very tight.

I hope that helps. Good luck!
 
Thanks for the insights! I did contact Vans and they responded with a similar fix as some of the ideas mentioned here. Basically removing the rivets from aft deck / longeron on the affected side and riveting a 1/8" x 3/4" strap on top. Then re-drilling the attach hole thru that. In the process I'm going to try to straighten the hole a little so it's perpendicular and use a MS21042 nut.

Vans didn't say anything about trying to remove the drill bit. What's the concern with that?

Matt
 
Blend

Leaving the drill bit in is willful ignorance, although ignORance can be bliss sometimes. :rolleyes: Generally good practices require removing and or blending damage prior to repairing, just so you know what you got.
 
MK77 said:
<snip> Vans didn't say anything about trying to remove the drill bit. What's the concern with that?

Matt
Click to expand...

Unquantified, but the small holes and a sharp, hard, steel tip (dissimilar materials) in aluminum could affect a stress riser, and/or corrosion. So, I would take measures to remove it, smooth the hole, and then, move on.

You want that bird to be airworthy for a long time.
 
Not really a matter of standards, I was more so concerned with doing more damage to the longeron in an effort to get it out (which the OB clearly did and STILL didn't get it out). Since it's not completely drilled thru the longeron I guess I'm hesitant to do more drilling from the bottom to try to extract it. Maybe the acid... or just carefully remove some material around it until I can grip it and wiggle it out then smooth the damaged area.
 
MK77 said:
Not really a matter of standards, I was more so concerned with doing more damage to the longeron in an effort to get it out (which the OB clearly did and STILL didn't get it out). Since it's not completely drilled thru the longeron I guess I'm hesitant to do more drilling from the bottom to try to extract it. Maybe the acid... or just carefully remove some material around it until I can grip it and wiggle it out then smooth the damaged area.
Click to expand...

If the drill tip is loose - or if you can wriggle it a bit ... - you could see if you could get it out with a strong magnet (Rear Earth Neodymium NdFeB) .... or electro magnet ....
 
I would recommend a Dremel tool or die grinder, with about a 1/8 diameter fine burr and clean the area up removing all traces of the bit and any gouges in the material. I would not necessarily make this a through hole unless necessary to complete the cleanup. After general cleanup, polish and round all edges. That will remoe the stress risers and invole the minimal material removal. From there you can see how bad it looks take a depth dimension and get an opinion from Vans.
 
I would confirm with Vans, but I think that you would do more damage removing, or attempting and failing, the drill bit.

It will be ugly, but it will be covered and only you will know it's there - the VAF readers will have forgotten... :)

Check and have Vans clarify their answer.
 
az_gila said:
I would confirm with Vans, but I think that you would do more damage removing, or attempting and failing, the drill bit.

It will be ugly, but it will be covered and only you will know it's there - the VAF readers will have forgotten... :)

Check and have Vans clarify their answer.
Click to expand...

I'd rather have a bit of damage which I know about, so I can clean it up or repair the piece in question, than have damage down in that hole caused by the drill bit which I *don't* know about (and may rear its ugly head at an inopportune time, like in flight).
 
Last edited:
Vans Response

Thanks all for the insights. I did hear back from Vans this afternoon and their opinion was to leave it alone.
 
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