TIME: 7 Hours
We last left off with a HS skeleton. Today I had to put some hardware onto the spar such as the hinges and the up/down stops.
I started to screw in the AN3 bolts hinge stops. One of the bolts wasn't catching on the nutplate. I started thinking that maybe the nutplate's threads were busted.. and the work involved in trying to change the nutplate. I was using a 3/8" socket to screw it in. I thought maybe if there was something to press it into the hole as it turned, the AN3 bolt would catch the threads. What tool did I have that would do it?
Just drop a big rivet into the socket! I'll be able to push the AN3 bolt and turn it at the same time. Great. Now that the hinges were secured to the front of the sparbox with four AN3's each, I then placed the hinge stops (2 per hinge) into the hinges.
In a previous post, I mentioned how Van's specified that the hinge stops were made from aluminum tube and they were 21/32" -0/+1/32 tolerance. Now I see why the tolerance was so strict. they fit in between the hinges perfectly. Again, these were secured with an AN3 bolt along with a nylock nut.
I also spent about an hour re-doing this because I was confused about what the proper torque should be for all of these bolts. So it appears that every bolt size (forget the length of the bolt.. its the width of the shank that matters) has a different torque value.. and those values are listed in Section 5 of the manual. The torque for an AN3 was listed between 20-25 inch-pounds (and 28 inch-pounds for an AN3 thats secured with a nylock nut). The bolts didn't really seem to go anywhere.
I found that what I had to do was to first measure the resistance of the bolt going in, then add that to the 20-25 in.-lbs. Nut plates are sorta mis-shapen and it takes a lot of force to re-shape it as the bolt goes through it. After all the threads of the nutplate were engaged, I tweaked the settings on the torque wrench to find out how much force it took just to turn the bolt. I then added that value to the rating for the AN3, 20-25"-lbs. Therefore, I set my wrench at 45 and screwed them in. 45 also "felt" right based on the size of the bolt. So the result is that the actual force exerted on the bolt's shank ends up being 20-25 (i used 25) .. and the force used to actually turn the bolt through the nutplate doesn't really count for anything as far as the tensions are concerned.. but you have to take them into account when screwing the bolt in. AN3's are apparently certified to 60inch-lbs, so we're definitely not over-torquing these.
Ok. That was a couple hour detour that I wasn't expecting. Continuing on.. the next step was to put the skins on. I found that the best way to do this was to use only a few clecos to get the skin lined up -- two clecos on the inboard-most holes of the sparbox.. two on the outboard-most. Then place rivets in every other hole. The rivets get the holes lines up 100% -- and with so few clecos in place, its easier for them to move the skin a little in whatever direction they want as they're inserted. Insert rivets into every other hole, cleco every other hole. Read the directions again. Start riveting.
We last left off with a HS skeleton. Today I had to put some hardware onto the spar such as the hinges and the up/down stops.
I started to screw in the AN3 bolts hinge stops. One of the bolts wasn't catching on the nutplate. I started thinking that maybe the nutplate's threads were busted.. and the work involved in trying to change the nutplate. I was using a 3/8" socket to screw it in. I thought maybe if there was something to press it into the hole as it turned, the AN3 bolt would catch the threads. What tool did I have that would do it?
Just drop a big rivet into the socket! I'll be able to push the AN3 bolt and turn it at the same time. Great. Now that the hinges were secured to the front of the sparbox with four AN3's each, I then placed the hinge stops (2 per hinge) into the hinges.
In a previous post, I mentioned how Van's specified that the hinge stops were made from aluminum tube and they were 21/32" -0/+1/32 tolerance. Now I see why the tolerance was so strict. they fit in between the hinges perfectly. Again, these were secured with an AN3 bolt along with a nylock nut.
I also spent about an hour re-doing this because I was confused about what the proper torque should be for all of these bolts. So it appears that every bolt size (forget the length of the bolt.. its the width of the shank that matters) has a different torque value.. and those values are listed in Section 5 of the manual. The torque for an AN3 was listed between 20-25 inch-pounds (and 28 inch-pounds for an AN3 thats secured with a nylock nut). The bolts didn't really seem to go anywhere.
I found that what I had to do was to first measure the resistance of the bolt going in, then add that to the 20-25 in.-lbs. Nut plates are sorta mis-shapen and it takes a lot of force to re-shape it as the bolt goes through it. After all the threads of the nutplate were engaged, I tweaked the settings on the torque wrench to find out how much force it took just to turn the bolt. I then added that value to the rating for the AN3, 20-25"-lbs. Therefore, I set my wrench at 45 and screwed them in. 45 also "felt" right based on the size of the bolt. So the result is that the actual force exerted on the bolt's shank ends up being 20-25 (i used 25) .. and the force used to actually turn the bolt through the nutplate doesn't really count for anything as far as the tensions are concerned.. but you have to take them into account when screwing the bolt in. AN3's are apparently certified to 60inch-lbs, so we're definitely not over-torquing these.
Ok. That was a couple hour detour that I wasn't expecting. Continuing on.. the next step was to put the skins on. I found that the best way to do this was to use only a few clecos to get the skin lined up -- two clecos on the inboard-most holes of the sparbox.. two on the outboard-most. Then place rivets in every other hole. The rivets get the holes lines up 100% -- and with so few clecos in place, its easier for them to move the skin a little in whatever direction they want as they're inserted. Insert rivets into every other hole, cleco every other hole. Read the directions again. Start riveting.
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