Rivet Edge Distance

SteveK · #1 10-17-2009, 05:12 AM

On my RV-8 horizontal stab, the inner ribs where they attach to the front spar do not have the minimum of 2 x D to the edge of the material that I had to shape. Do I have to remove them and work to get more edge distance? I have already redone one of them, and it there still isn't enough distance.

apkp777 · #2 10-17-2009, 06:36 AM

Hmmm, you are in a place we have all been. Nothing more frustrating than insufficient edge distance.

Here's my take, you can take it or leave it. You need 2D to prevent cracking and deformation of the mating metals. Okay, we all know that. But, sometimes you just gotta move on. The ribs are not the most important structural element on the plane. If it's slightly less than 2D I would let go. Oh, I hear the gasping from the readers. But I can't tell you how many times I have seen sheetmetal repairs become complete hack jobs, because the person tried to "fix" one bad rivet or marginal edge distance. I shot a million rivets before my RV, I have screwed up my share of rivets. Unless they are REALLY ulgy, I know better than to try to fix them. I witnessed a situation at Boeing where a guy put a rivet in a tooling hole. 1/4 diameter rivet. No Problem. Except the inspector didn't like it. They drilled it out and then the tool to mount the door didn't fill just right. So they had to install a freeze plug, which got screwed up 2 or 3 times. In the end they had to change the entire fuselage frame at about 400 man hours and a ton of work.

sprucemoose · #3 10-17-2009, 03:38 PM

http://www.vansaircraft.com/public/Specs.htm

The Mil-spec on riveting. Everything you ever wanted know and then some. It covers the edge distance question quite clearly. Bottom line, 2X is a rule of thumb, just like 1.5X shop head diameter. The actual required dimensions are slightly less than these rules of thumb, and you should be using the actual numbers when deciding whether or not to drill out a rivet. As was stated, you often do far more harm than good trying to replace a marginal rivet.

RV505 · #4 10-17-2009, 07:54 PM

There is no way the current rib is going to obtain a proper ed. I am going to remake both center section ribs and make the flanges a about 3/8 longer. I'm starting with 2024-0 and making new dies. Easy repair. I had make repairs for 757's the same way as the factory parts were short for the floor beams. I am waiting for the metal to be delivered.