Below is the torque value chart from section 5.20 of the builders manual. The bolts used for the Wing Rib to Main Spar installation are all AN3 and use MS21042-3 Self Locking Nuts. As described below, you first need to determine the friction drag torque for the bolt/nut combination. Van’s tests showed an average friction drag torque of 14 in-lbs, but indicated results may vary. I also had a 14 in-lbs friction drag torque value, so I will use the same as Van’s. So, for the correct torque value, you take the friction drag torque value (14 in-lbs), the value shown in the chart (28 in-lbs), and add them together for a total torque value of 42 in-lbs. This bolt/nut combination will get torqued to 42 in-lbs. In Post #17, you can see an excerpt of where the bolts go and what orientation.
Wing Ribs #14, #13, and #12 do not utilize bolts (only rivets), so they are excluded for the time being. The plans state to cleco the W-1012-L & -R Outboard Wing Ribs and all W-1011-L & -R Inboard Wing Ribs (except the inboard most W-1011-R) to the Main Spar Assembly.....as shown in Step 1 below.
There is a note to NOT install the nuts and washers on the three most Inboard Wing Ribs (#1, #2, and #3) at this time. Additionally, in the second part of Step 3, it says “for the three most Inboard Wing Ribs, it will be necessary to push the bolt out of the way to set the rivets”. What rivets? It never specifically says in the plans, but it’s the small AN426AD3-3.5 rivets installed in the forward most hole in the forward tabs of the seven W-1011-L & -R Inboard Wing Ribs (Ribs #2 through #8).
The excerpt from above also shows the locations and size of rivets to install for the Wing Ribs and Main Spar. Most of today’s session was devoted to installing these rivets and I used the weapons below.....
Because of how the Wing Ribs are made , you are not able to get a straight shot on the manufactured head of the rivet. So, that is the reason I used the Offset Cup Set. I really don’t like using this rivet because it takes a few more hits to set the rivet.....because it’s offset. I personally also find it difficult to ensure the Set is square to the rivet head. I have to admit, I have a few “smiles”. I normally use my Sioux 2X rivet gun, but because all the rivets used are #4, I used my buddies 3X gun. The tungsten bucking bars are awesome! Get yourself one....or two.....you won’t regret the purchase.
There are 72 rivets that attach Wing Ribs #1 through #13 to the Main Spar Assembly. (Wing Rib #14 is only clecoed at this point and will be riveted later along with one of the Leading Edge Ribs). The vertical rows of rivets are the shop head for Wing Ribs #13, #12, and #11.
Here is where I deviated from the plans just slightly to complete Wing Ribs #1 through #4. Because they are so close together (wing walk area), it is difficult to get the rivet gun in between them. So, I removed Ribs #1 through #3 and riveted Rib #4. Then, clecoed Rib #3 and riveted, then #2, and then #1. This gave me plenty of room for the rivet gun and kept the Ribs out of the way.
Additionally, I previously did not rivet the Torque Tube Support Bracket Assembly to the most Inboard Wing Rib. If you follow this step in the plans and rivet the Assembly to the Wing Rib, you will not be able to get your rivet gun on the manufactured heads of the rivets from the Rib to Spar. So, I riveted Rib #1 to the Main Spar FIRST and then riveted the Assembly to the Rib.
The picture below shows the #1 Wing Rib riveted to the Main Spar and the Torque Tube Assembly riveted to the Wing Rib. You may notice that one of the rivets from the Assembly to the Rib #1 doesn’t look like the others. Ideally, you want the manufactured head of the rivet on the thinnest of the two pieces of aluminum. Again, because Ribs #1 through #4 are close together, you can’t get a rivet gun in there.
I used my pneumatic squeezer to set the very top and three middle rivets (pictured above and below), my had squeezer to set the very bottom rivet (pictured below.....assembly was flipped upside down), and the rivet gun/bucking bar to set the rivet in the opposite direction. Because of the Flange Bearing, I couldn’t get either squeezer on that rivet and had no choice but to set it the opposite way.
Anyway, Section 14 is now complete. Section 15 will be the Rear Spar and I will start there next time.