Lower Longeron - WD603 lower engine mount bracket edge distance

[bullojm1]

I was working on drilling my lower longeron to the lower WD603 lower engine mount bracket today for AN3 bolts. I drilled 4 #30 holes to act as pilots before I drilled the #12 holes for the bolts. I marked where the holes would end up on the bracket, and noticed that my edge distance is off by a large margin. My edge distance is 1/4" on the steel bracket, when it should be in the neighborhood of 3/8" - leaving me 1/8" off. Attached is a picture for clarity:

My guess is that this is OK since the joint is (a) in sheer and (b) the edge distance issue is on a heavy steel bracket. Build on (most likely) or worry?

Any advice is appreciated!

 

[Pmerems]

Edge distance

Mike,

If you center the bolt on the longeron then it will be 3/8" from the longeron edge. But since the weldment flange contacts the 1/8" leg of the longeron the flange is only 5/8" overlapping the longeron so you edge distance on the steel would only be 1/4". This is by design. You could offset the bolt from the centerline of the longeron 1/16" to average out the situation.

Keep in mind these measurements are "ideal" conditions. If you don't radius the weldment flanges or clamp the weldment in position properly your edge distances will be less then ideal.

I went through the same decision making when I drilled my weldments. I clamped and triple checked everything before I drilled them.

The upper weldments required a lot of fiddling to get them to sit properly against the longeron.

I hope this helps.

 

[bullojm1]

As a follow up to my original question, I called up Van's this morning and spoke to Ken about this issue. For the first time, I didn't get the "build on" response. He said I should try my best to get the edge distance on the steel. His recommendation was to elongate the #30 hole inboard as much as I could and then try to drill the hole larger.

After doing the math, I can only move the hole over 1/32", which still is 3/32" from meeting the minimum edge distance. I bit the bullet and got another 5' length of lower longeron shipped out to me.

I hope this helps someone else out.