miyu1975

miyu1975

Well Known Member
Looks like I will welding shut the hole. It was perfertly perpendicular but I did not notice that one horn was taller than the other, resulting in a close the edge #30 hole...still would have to open this hole to number #12.

Someone told me welding steel makes the steel harder and more difficult to drill into.??....

any advice...:(:(

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Rivet instead of weld.

A simpler way of making this repair would be to rivet a doubler of equivalent thickness onto the original horn to give sufficient edge distance. The doubler should cover as much of the original horn as possible for strength.
There is plenty of clearance between the two horns.
 
I like that idea much better. Would put the doubler on the inside or outside of the horn. Also, should the doubler be steel too?
 
Yeah, that's 4130 steel.. You'll want to stick with the same stuff, so you have the same strength.

Mis-drilling those horns is a pretty common error. Ask me how I know. :rolleyes:

Phil
 
horn drilling

I am not an engineer, but would imagine that any doubler here should be steel. To address the welding and drilling (I had to do the same) I found drilling the hole difficult too. Ended up cutting a larger section of the horn out and weling a new piece in so that the new hole was in vergin material and not the weld. Also, found that it takes a very good drill to drill that stuff anyway. I found that a step drill seemed to work much easier. Once you have a hole it is much easier to drill it larger to the correct size. Happy drilling.
 
miyu1975 said:
I like that idea much better. Would put the doubler on the inside or outside of the horn. Also, should the doubler be steel too?
Click to expand...

Yes, as Phil said, it should be 4130. Same as the material you are reinforcing.
I personally would put it on the inside (between the horns). You could put it on the outside, but if you do, make it as large as possible radiusing the edges to fit in the channel.
 
While you are at it make a doubler for the other side and if you make them thick enough you will not need any washers.
 
I made the same mistake. I was planning on getting it welded, but if I were to some how screw it up again after that I'd be pretty upset with myself.

The doubler sounds like a great idea. Should it be attached with aluminum or steel rivets?
 
I guess I am not alone in screwing this up, despite all the attention I gave it the two holes were not lined up perfectly. So, we ended welding a piece of 4130 as a doublers and redrail again. A very good coat of primer & paint has cover it to make sure rust won't get there. I can't say I have much time in this plane, my first annual is due this month and 190 hours later, there has been no issues so far. I am hoping to stay that way for the many years to come.
 
finding 4130 steel is proving to be difficult. lowes and home depot have steel but not 4130.
 
You won't find it at Home Depot or Lowe's... Aircraft Spruce or Wick's or similar will carry it. 4130 is an aircraft material.

Rather than an obvious doubler. the original idea of welding the hole closed and redrilling it is a pretty good one. It'll work fine.

Another approach is simply to replace the part.

Still another approach, since there's plenty of material in the direction of load, is to ask the factory if it would be acceptable with the small edge distance remaining. If yes, a machine shop could drill the larger hole off-center so that no more material is lost at the edge.

Who wants an obvious patch on an external part?

David
 
David Paule said:
....the original idea of welding the hole closed and redrilling it is a pretty good one.....
Click to expand...
Maybe I am missing something, but how would welding the hole closed help? If I interpret the original post correctly, the builder drilled through the longer of the two horns FIRST. As I recall, to eliminate the possibility of short e.d., the plans would have the builder drill through the shortest horn first then on through the longer of the two horns.

Let us say you did plug that hole. You still have to match drill using the hole in the other horn as a drill guide and you'd end up redrilling a hole in the exact same place as before only this time through the fresh weld.

In this particular situation, I see some form of 4130 doubler as the quickest, cheapest, easiest solution. The photo illustrates how I *might* approach the problem but I emphasize I am not a qualified engineer. Before getting underway, I suggest first contacting Van's (or other equally competent engineering resource) to see if this or a similar repair is a viable solution:

efgygz.jpg
 
My elevator horn is not external...I got that one right.

I like the illustration for the doubler. I plan to make the doubler when I get some 4130. The plans say to drill AFT horn first. It doesn't mention anything about drilling the "shortest" horn. Although I wish it did and I wish was more careful to have noticed prior to drilling.
 
I had 10/32" edge distance on one of my horns (center of hole to edge of horn). Van's said that was more than sufficient for this steel part. Not only because it's steel, but also because all of the force on the hole is acting forward and aft and not up and down.

Not sure if you have less edge distance, but just thought I'd throw my experience out as a data point.
 
Per suggestions given...here are my results. I ordered a sheet of steel from vans (same as the horns are made of). I cut it to shape and riveted it on...came out great. I primed and painted it black so that it would stand out to me every time I do a conditional inspection and remind of this part of the building experience...actually I just didn't have any white paint.

all in all this wasn't difficult, I think easier than trying to weld the hole shut.

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Couple notes.

No, welding 4130 doesn't make it hard to drill. Allowing it to cool too quickly after you weld makes it hard to drill (quench hardening).

If you're using a TIG, clamp a brass block over the backside of the hole. That side of the welded hole will be perfectly flush, as the brass block won't weld or stick. Warm it up with a propane torch before welding and it will also provide thermal mass to slow the cooling rate; see above.

The usual reason to weld up the hole and try again is one horn drilled too far forward or aft, thus the elevators are at different angles. Welding is an easy fix for that problem. Rick is right, welding the hole closed wouldn't fix an edge distance issue, but you could easily weld on a small length extension.
 
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