<October 26, 2006>
Riveted Left Leading Edge to Spar
Oh boy, what a night. I riveted the left leading edge to the spar tonight. I used blind rivets to do this job, MSP-42, -43 and -44 rivets from Aircraft Spruce to be exact, but that isn't the end of the controversy. I riveted (pulled) these rivets from inside the leading edge. Why use blind rivets? Why from the inside? Well, first of all, in my opinion certain blind rivets blind rivets are completely acceptable here. Van's has said to many builders that the use of LP4-x rivets is acceptable here, and the LP4s are pretty soft as rivets go. I decided to step it up a bit and use MSP rivets here. They have a Monel (M) head, with a steel shaft (S), and a protruding head (P), and by my calculations are very similar in strength to solid rivets. I am likely to catch flack for that statement, but do your own calculations and see for yourself. Don't take my word for it, and I am not recommending this method, only documenting what I did.
Why use blind rivets here in the first place? Because riveting the LE ribs to the spar involves grinding down a rivet set and you need two people for the job. These certainly aren't big issues, but I wanted a easy method I could do myself.
Why from the inside? That one is easy, I wanted the factory head of the rivet to be on the thinner material (aft flange of rib). This was slightly painful, but I am proof that it can done. I also did this because even with the face of my cheap-o rivet puller ground down, I was having a hard time getting the puller on the shaft of the rivets due to their close proximity to the aft rib webs.
Warning: If you are reading this and get the idea of doing this for yourself, I want to caution you. Pulling these rivets from inside (arms through lightening holes) took A LOT of hand strength, especially for these hard MSP rivets. The two outboard and inboard aren't that bad, but the two interior ribs had me second guessing my decision to do this.
Using my hand seamer I made sure the aft flanges of the leading edge ribs were straight as some were somewhat distorted after the leading edge rivet process.
Here is what the MSP-4x looked like from inside the leading edge. Pulling them from the inside kept the flanges nice and tight against the spar web.
From below. I used different length MSP-4x rivets based on the thickness of the spar at each rib.
After the rib to spar riveting, I squeezed all the rivets along the leading edge skin and spar flange. This was easy except you have to be carefull as there are a few nutplates that get in the way of the squeezer. Once complete, it was time to install the tank.
After installing a few of the screws I noticed a slight pillowing of the tank skin along the leading edge. It was very minor and I know this is a common issue, so I am going to deal with this later.
This gap where the skin attached to the spar and tank did concern me a bit though. Seems the a lot of stuff has shifted slightly during riveting. It was late and I was tired and sore from all the riveting. Rather than dealing with this now I called it a night.