Edge distance

[Maxrate]

Happy New year to everyone!!

I'm working on the piano hinge for the flap and DWG 14A refers to a "minimum edge distance" of 3/16"

If I remember correctly, edge distance is 2 X diameter. It seems like edge distance should be from the edge of the hole to the edge of the hinge material. But it looks like in the picture Van's is measuring from the center of the hole to the edge of the hinge material. I know that critical edge distances such as the rear spar attach hole that has to be drilled later has zero tolerance for error. Anyone else run into this?

Thank's

 

[PIN 37]

Edge distance is always centre of the hole to the edge

 

[Rick6a]

... It seems like edge distance should be from the edge of the hole

As Phil mentioned, edge distance is always measured from the center of the hole. Here's a quick tip
on a technique used to achieve minimum e.d. (2 X dia.) when a pilot hole has short e.d. to begin with
and you want the full size hole to meet minimum e.d. standards:

http://www.vansairforce.com/community/showthread.php?t=11769

 

[jmjula]

You can also think of edge distance being 1.5x from the edge of the hole too.

 

[Maxrate]

Thank's for the clarification. The piano hinge on the first flap narrows slightly at the root and I was concerned about having to go with Vans oversized hinge. I'm finding out that its just aluminum and can always be fixed..

 

[Mel]

Not exactly relevant......

to this particular situation, but remember when pushing specs toward the limit, the flaps carry more dynamic load than any other control surface. They are the only control surfaces that are pulled into the airstream and held there continuously.

 

[Maxrate]

I hate to resurrect this thread but I have another edge distance issue. While match drilling the A-408 spar reinf plate to the A403PP aileron spar I noticed that after the #12 bit is run thru the holes for the attach hardware that holds on the aileron brackets, the parts lack the edge distance we always hear about (2 X the diameter from the center of the hole). I sized everything up to the full sized drawings and it all seems to fit the plans. I realize there are doublers on top of doublers, but why does Vans depart from the edge distance rule on such a critical part like aileron attach hardware?

Here are some pics.