Wings are on
The wings are installed for good. All of the wing bolts are in and torqued.
For the past two days, Tanya, Watson, and I have spent the majority of the day at the hangar. Saturday morning started with an army of visitors inspecting my work. They didn’t find much :). It was Seth, Deene, Stu, and Gary to start. I think the little girl was Seth’s grandchild, not sure? Watson isn’t so sure about “little” people. Even while people were hanging around, I managed to get quite a bit of real work done. We pulled the wings off of the fuselage and I got all of the lower intersection fairing nutplates installed. I’m practicing the art of picking my productive tasks carefully while people are around. Nutplate installation qualifies for easy working and talking. However, I waited until a lull in the people activity to put on my careful thinking cap and cut and flare the fuel and vent tubing protruding from the fuselage that connects the wing tanks. Jim Andrews (RV9A) had cut some little lengths of tubing just the correct length to measure the location of the tubing cuts. I borrowed his templates and they were spot on on my plane too. Big surprise, not. So, how long to cut them was no big deal, and all worked out fine. For those that don’t know why I’m going on about cutting a piece of tubing: In the tri-gear RVs, the main fuel pickup lines to the tanks are bent through a bunch of structure in the cabin that is very, very difficult to deal with. If you cut the pickup tube too short, you’re in for a couple of days of the worst aggravation having to remake that tube.
We have a radio in the hangar that we use to listen to the local aircraft traffic while I work. In the afternoon on Saturday we heard someone having trouble getting the retractable gear down for landing. They did a low pass so someone at the unicom station could take a look. We peeked out the hangar door as they went by. Yep, no wheels. They headed out a couple miles to try to persuade the gear down. Not much we could do here. A couple minutes later, Stu came wondering around. I very casually mentioned that someone just did a low pass with gear issues. He paused for a moment, then sprung into action. Thirty seconds later, he had his RV8 pulled out of his hangar and was on the radio asking the other pilot if he would like him to come up and take a look. The other pilot basically said “hell yeah!”. Stu was in the air within about another two minutes. At about the time that Stu got airborne, the other pilot announced that he “got three greens!”. He was clearly stressed and the relief came through loud and clear on the radio. Standing out on the ramp in front of our hangar, we watched Stu join up on the other plane for a close (and I do mean close) inspection. Tanya got a picture as Stu closed in. All looked good and an uneventful landing was made. Tanya and I commented to each other that the front row seats were really worth the price of admission.
Oh, we’re supposed to be building an airplane… Apparently there is more fun to be had at the airport than just building. But don’t tell Watson that, he is getting this “hangar dog” thing down pat, sleeping on the hangar floor. At the close of Saturday, we got all of the wires pulled through the conduit in the wings and the wings back on the plane with the temporary hardware.
Sunday, late morning, after breakfast tocos, we dove straight in installing the final wing bolts. I laid out all of the close tolerance bolts while Tanya started tearing down the wing cart. There is a lot of talk about the difficulty of installation of the final wing bolts in the tri-gear models because of the gear leg weldaments that are in the way of torquing the nuts. I’m hear to say that it doesn’t have to be the terribly frustrating task that some turn it into if you have a few key tools and accept some simple truths that may be contrary to normal approved construction technique.
I lubed up the shank of the bolts with LPS2 carefully avoiding the threads. The critical tools are the rivet gun with a flat set, a large flat head screwdriver you’re willing to destroy, and (very important) a strong air ratchet. I started with the most difficult bolt, the large lower outboard bolt. This is useful because you need all the access you can get to the nut of this bolt without the nuts of the other bolts in the way. I drove the bolt in with the rivet gun. Most of them drove in relatively easy. Only a couple bolts did I have to really hit them long and hard. I did have the air pressure in the 90psi range. Ok, so first lower outboard large bolt, with a washer under the head, driven in carefully with only two or three threads showing. No washer under the nut. I used some hemostats and a flat head screwdriver to carefully tease the nut onto the threads. Knock the bolt in another 1/8″, and spin the nut on a little more. Rinse and repeat until the nut hits the fiber lock. It is super important to not drive the bolt in too far without the nut threaded on the end as you won’t be able to get the nut in place because of how close the gear mount is. This is a good time to attempt to measure the drag torque of the bolt in the hole. Use a torque wrench to see how much torque it takes to spin the bolt in the hole. On mine, it was about 9 ft-lbs.. This will be added to the target torque value since we’re going to tighten these bolts from the bolt head side (not normal practice). Now, take that big flat head screwdriver and jam it in place between the bottom of the nut and the bottom plate of the gear mount from the inboard side. Now that nut isn’t going to turn. Turn the head of the bolt with the air ratchet while holding the screwdriver in place. My air ratchet is only good to about 50ft-lbs, so I had little concern about over torquing the large bolts with it. Now, torque this first bolt while the nut is still immobilized. To what torque you ask? I’ve heard (only second hand) that Vans support says 37-41 foot-pounds for the large 7/16″ bolts, and 50-70 inch-pounds for the small 1/4″ bolts. So I set my torque wrench to 49 ft-lbs. First one done. Next I drove in a top bolt, then the rest of the bottom ones. Same deal with torqueing from the bolt side on some of the other bottom bolts, but you can get an open end wrench on the nut of the rest of them. Also, be careful not to drive the second large (inboard) bottom bolt in too far without the nut threaded on as it has the same nut clearance issue as the outboard bolt. After five hours of my body all waded up in the cockpit, and we have all of the wing bolts in and torqued. No sweat, no blood, no broken parts. I call that major success worth reporting.
After a quick celebration with a sip of water, I moved on to getting the final hardware in the rear spar attach and forward tank attach bracket. Toward the end of Sunday, Tanya and I hung the flaps and started to mark the trimming that needed to be done for the flap pushrod and rod end bearing in the fuselage skin.
My wing cart is free for the taking to anyone that wants to come get it.
