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Pushrod Rod End - Edge Distance issue

bullojm1

bullojm1

Well Known Member
I was working on drilling the aileron pushrods to the threaded rod ends tonight and I came up short on the holes in the threaded rod ends for the MSP-42 blind rivets. Here is a pic (the one on the left is the one in question, the right one is where it should be):

RodEnd.jpg


Since the pushrods are critical, I don't want to ignore this possible issue. My options now are:

1) Move on
2) Order new ends
3) Call Van's.

What do you guys think? I appreciate any input.
 
I have come to find that for myself if the question is important enough to post on a builders board it's important enough to call Van's. Looking at your pictures I would say just off hand that you should build on. It seems, to me anyway, that you have met the edge distance requirement. I recently had an edge distance problem of my own in the rear wing spar to fuse attach bolt hole. While talking to Ken he said there are only a couple of absolutely critical edge distance holes, and yes, indeed I had found one of them. My thought on it is if this area of the push rod was so bloody critical that you had to have dead on accuracy for strength Van would be using something other than pop rivets there anyway. I'm seeing plenty of material for the rivets to hold.
 
I agree with the move on. There seems to be plenty of space there and there is not that much stress put on those areas. My ends were so hard to put on that I didn't take them off once they were on. I tried but I just couldn't get them off. I drilled the holes and put the rivets in. I bet you that tube with your drill locations could probably hold well over 500lbs but probably way over 1000lbs. If you have to put that much stress on that aileron rod it might be better that it fails because I would hate to see the rolls that come from putting that much force on it.
 
You are fine. While you may be short on edge distance using the 2X rule-of-thumb, if you take a close look at the mil-spec on riveting, you'll find that 7/32 (0.21875 or .219 rounded to the nearest thousandth) is exactly what the spec calls for. So you are not only "probably OK" you are within the specification.

reference: http://www.vansaircraft.com/public/Specs.htm
 
Read this.......

A doctor friend of mine wanted to see his -4 do rolls and loops and so on. He asked an aerobatic pilot/RV owner to do some so he did while Doc watched from the ground. After landing and shutdown, the aero pilot just happened to look down in the rear cockpit and noticed that the pushrod going to the elevators had no pop rivets in the end that attached to the control column!! :eek: The press-fit friction was all that made the difference between life and death. It also shows how little control pressure is needed.

Be sure and check the airplane very thoroughly from one end to the other before its maiden flight. This was overlooked by the builder, the Doc and the DAR.!

Regards,
 
Update

I just got off the phone with Ken at Van's and he said it shouldn't be an issue. He said that 2D for edge distance isn't an absolute, it is just easy for people to remember. Also, he said that thickness of the rod end and tubing are another reason that he is not concerned.

Thanks for all the responses to my inquiry. Since no one gave me a reason to worry, I am going to press on.
 
add another rivet...

I had the same thing happen and just added additional rivets between the ones already there, the belt and suspenders approach.
Good luck with your building.
Rick
 
Rick,
If I remember correctly, the spacing for the 6 rivets is 19/32" - which gives you a pitch between rivets of about about 5D. (MIL-SPEC for rivet pitch is between 3D and 12D). If I were to put 6 more rivets in, the spacing would be 19/64", or 2.3D. As Jeff Point pointed out, I am indeed within spec of the official MIL-SPEC (greater than 0.219). However, your solution would put you out of spec.

I appreciate your input into my problem, and please don't take this as a flame of any sort. I am just trying to see if there could possibly be a safety issue with your solution.

Anyone else agree or disagree with my logic?
 
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