Still Trying to Prime LE Parts

Lousy painting weather and other stuff getting in the way of priming my LE parts. My wife managed to locate a set of stainless steel turkey basters, complete with a cleaning brush, thermometer, and injection needle that screws into the threaded end of the tube - all for a reasonable $10.00 price. I should be able to use those repeatedly for measuring out small quantities of primer and catalyst. The only problem is that you cannot see through the metal tube, but since I use pre-marked paint cups from NAPA auto parts to measure all my quantities, that is really not a big deal.

I also found and bought two large syringes at the Walmart aircraft supply store that are supposed to be used for measuring out 2 cycle engine oil. These are plastic, so they will suffer from the same one-time-only use fate as the other plastic turkey basters did, but they will certainly fulfill their purpose.

Also had to focus on getting two teeth crowned in the past couple of weeks. The trailer is on the short list of prep steps now. Airventure is only a few weeks away and I am really excited to attend this year. The only thing I am really worried about is the weather while I am traveling.

I had also waited on priming the other parts because I was trying to decide if I wanted to go ahead and prime the entire subskin before I do any final trimming. I decided to do just that, since I still have to figure out the jigsaw puzzle that I need to put together from the two overlapping access panel openings in the skin. Here is the subskin after a preliminary scuffing of all sides:

This part had a lot of scratches and abrasions from all the trial fittings and repeated assembly and removal steps so far. It was a bear to get some of the deeper scratches out. None of them were really all that deep. they just looked bad against the remaining shiny alclad layer that has now been removed. I still have some final cleaning to do on this part before it will be ready for priming. I think it may actually fit a little better in between the skin and the ribs after removing the alclad layer. I hope to get everything primed before the end of this week.

The rest of this next series of pics is more for my benefit so that I do not lose the markings and measurements and thoughts that I scribbled down on the subskin  before removing them this evening. I may need to reference them when I am ready to start trimming down the subskin to its final form. As I start trimming this part it will start to make more sense.

KPR....

Prepping the Trailer for Airventure 2017 and Finally Formed the Edges of the LE Skin

After a 2 month stint in the shop, I finally got my trailer back. I had delivered it back in April in hopes of beating the Memorial Day rush, only to see that holiday come and go with the trailer still in the shop. What a comedy (hardly) of problems - mostly weather related - but not all of them.

I had a larger than normal laundry list of fixes this year: Re-weld a broken step support, find and fix an air leak in my water supply line from the water pump, Check to see if I have a water tank leak in my spare water tank, fix a leaking gray water dump valve, re-attach and seal the driver side front corner molding that joins the corners of the walls of the trailer, and the annual wheel bearing repack.

Week one started with the shop telling me that 2 techs had quit that week, so they did not even look at it. Weeks 2 and 3 ended up with freezing cold temps that prevented any type of water  repairs. Week 4 was the week of softball sized hail that pretty much decimated the west side of Denver. Luckily they had pulled it into a stall to do the bearing pack by then, so I lucked out big time on that.

Then came the day that they called to tell me that my axles and were on backwards and my brakes were improperly installed and it would take brand new axles to fix it. Now folks, I have owned this trailer since 1998, and in all that time I have serviced the trailer brakes about once every other year for one reason or another. In all that time I have never had a single tech inform me that my brakes were upside down. This includes the previous 2 years where I did have extensive brake work done by the same shop! That led to several arguments, including comments like "what the hell are you doing with my brakes. That was not one of the things on the list of fixes, because they were working fine. You should not be touching my brakes!"

Then came the 2 weeks I had to wait because they found leak in my main sink's P-Trap, so it needed a new P-Trap. This turned into another nightmare because they had to order the right part. The first attempt at this ended up with the supplier sending the wrong part. Then, several days later, they sent the right part, but it was missing one of the required attachment fittings.So on and on it went......

Then, to top it all off, I finally went to pick it up, only to discover a problem with my front trailer brakes locking up under certain circumstances. So this ranks right up there with some of the worst trailer service experiences I have ever had. One thing I will never dispute - tent campers have it SOOOOO much easier than those of us that haul the boxed metal RV's around. Although they have to do without many conveniences and amenities that an RV provides, the reality is that RVs are pretty much an extremely condensed version of a second home, with many of the conveniences that a normal home provides.

Unfortunately they also require even more maintenance than a regular home to keep them operating properly, because of the pounding and vibration that they take while moving on the road. This is not unlike the maintenance requirements of an airplane, due to the vibrations and high stresses that they must endure. So I consider all the RV maintenance I have to perform as a kind of preparation for the airplane maintenance that will be required eventually.

A couple of years ago, while departing Omaha, Nebraska enroute to Oshkosh, I encountered some of the worst road construction I have ever experienced in my life. I literally think that they forgot to leave cones up along a stretch of I-80, and as a result, I literally thought that the entire frame of my trailer was going to be ripped apart,  not to mention my truck.It's things like this that force you to keep maintaining the unit every year. 2000 mile long trips are also not the normal expected trip length for a small travel trailer. So I also need to pay extra attention to making sure that things like the welds for the spring suspension, the axles, and the bearings are all in tact.

Anyway, now that I have my trailer back, it was time to start on my usual list of chores and checks that I always have to perform when I prepare for the 2000 mile round trip to Oshkosh from my home here in Denver. After spending most of the weekend checking everything out, it looks like it should be ready for the next journey to Airventure, assuming my trailer brakes are working properly. I will be conducting more tests on those in the weeks to come, but everything else seems to be in good working order.

Since that took up most of my weekend, not much done on the plane. However, I did finally get up the courage to perform the edge bend on the left wing LE skin edges using my edge forming tool I mentioned in the previous post. I struggled a bit with how I wanted to do this. I was concerned about securing the skin to keep the edge from moving while I ran the tool across it. I did not want to reattach the ribs because this would have contaminated the cleaning job I did several days ago. So I came up with what I thought was a great plan - I would use a ratchet strap and my wood forming blocks shaped like the wing ribs to force the top skin down into its finished shape and hold it tightly in place. This did not work for a number of reasons - the main one being that the wood rib forms stuck out a little too far and would interfere with the tool, which requires about 1.25 inches of clearance to allow the slight bend in the edges to be formed.

So I abandoned that idea for a much more low tech solution as shown in the next pic:

I slid the skin as far out onto the edge of the table as I dared, and placed some weights on the skin. In retrospect I should have clamped the bottom skin down, but I got lazy - and paid the price for it. The first edge to be formed was the top one. I did my best to follow the setup instructions from Cleaveland tools, and then got ready to form the edge. The tool was drawn across the edge after being clamped to the skin. the slight bend, or crease in the skin as I prefer to call it, was formed as expected with no issues:

The last pic that I have shows where things did not go as planned because I did  not flip the skin and re-clamp it tight to the table. Instead, after I finished forming the edge of the upper skin as shown above, I decided to leave everything in place and turn the tool upside down so I could do the other edge without rearranging the skin.Notice the multiple lines in the next pic where the tool slid off the edge because I was not holding it properly. Fortunately this is not seem to deform the edge of the skin at all, so I think I am OK. If I had made the same mistake that many other builders do when they use this tool by tightening the clamping pressure of the tool on the skin too tightly, it could have been a much different story and a very bad outcome.

I basically went back over the bad areas where the tool slipped and reran the tool over them once or twice to make sure then bend was applied in all the right places. The slight line that runs through each rivet hole is the correct indication that the bend has been applied properly to the edge. This should keep the edges from curling up and creating a gap between the skin edge and the wing spar when they are riveted in place. Glad to get that over with. Now I can focus on getting some parts primed and reassembled so that I can keep moving forward.

KPR.

LE Prep Episode 3

Edit 6-9-17 - I revised some of this post to make it more readable, and also to correct a gross oversight on my part.  I previously used the term "kerf" to describe the process of applying a small bend in the edge of each skin so that it provides some spring back when riveted in place to prevent the edge from curling upward and creating a gap between the two surfaces. This was not the correct term to use, as kerfing is an entirely different procedure for a different reason.

The other problem with this is that in previous posts from long ago when working on my rudder I may have also referred to this process as "rollling" the leading edge, which is also an entirely different procedure for a different purpose. The problem is with the way the edge forming tools is contructed. It is basically a set of modified locking pliers with a set of custom-positioned rollers welded on to the ends of the pliers at a pre-determined angle. The "rollers" on this edge forming tool can be confused with the term "edge rolling," and thus the confusion.

SO let me stand corrected - the official name of the tool that I am about to use is an EDGE FORMING TOOL. It uses a set of rollers to force a small bend in the edge of the skin. This process has NOTHING to do with kerfing, which is a procedure that awaits me whenever I get back to working on the main wing skins. There, now I feel better..... ----------End edit.

No pics tonight. One other thing I almost forgot about was the outer edges of the LE skin. So I went out last night and ran my finger across the edges, and it took less than a second for me to discover the same small bumps about 3 inches apart from each other along the edges. These are the separation points where the skin is still attached to the metal blank that is placed into the CNC machine to perform the initial cutout of the LE skin. Vans does not remove these seemingly minor bumps from the skins. They can, however, act as stress concentration points, and could cause metal fatigue and cracking if they are not smoothed out.

So, like everything else with this kit, all these little bumps along the edge need to be filed and smoothed. I used my flat jewelers file and a piece of 320 aluminum oxide sand paper glued to a 1/2 inch wood dowel to file and smooth all of the bumps. I also had to residual scratches that needed a bit more work to smooth those out before priming everything.

A call to Vans also revealed two more things. I need to slightly round the corners to get rid of the sharp corners - another potential stress concentration point on the skin. They also confirmed that I will want to slightly bend the edges of the LE skin where they attach to the wing spar flange. So now I have to find my edge bending tool, practice with it on some scrap metal, and hope like heck that I don't screw up the edges on the LE skin. I think I will need to clear off a large area on my work bench so I can clamp down each skin edge so I can use both hands to draw the edge bending tool along the skin edges.

As I recall, one problem many builders were having with applying this small bend to the edge of the skin was that they were using the tool incorrectly. They close the pliers too tightly so it is extremely hard to run the rollers across the skin to achieve the small bend. Then, when they start to apply the bend the rollers slip off the edge, messing up the edge of the skin along the way. Only slight pressure is needed on the skin while the tool is drawn toward you to create a very small and barely noticeable bend on the edge of the skin.Cleaveland Tools now has a video on their website that demonstrates how to set this tool up and use it properly.

Tomorrow I will probably scuff and clean the subskin, apply the bend to the edges, and on Thursday I should be ready to prime a bunch of metal again. Then more assembly, measuring, disassembly, cutting, deburring, etc., etc.

And to think I was going to have my fuel tanks done by the end of this summer - yeah right!

KPR.

LE rib and skin prep for primer - part 2

Had some family obligations this weekend, so not a lot of time spent on the plane, but I am inching ever closer to spraying more of that expensive epoxy primer on my remaining LE parts. Here is pic that I love showing to folks so they can see the difference between brand new "tools" and what it looks like after you use them during the build. On the left is a brand new, as yet unused medium grade (maroon) scotch brite pad. On the right is the one that I started using when I prepped the first two LE ribs and a couple of other parts. Since then I have prepped the 4 remaining LE ribs, and the interior LE skin.

When prepping my main wing ribs for primer a long time ago, I decided to follow a practice that Steve Riffe used to clean his parts prior to priming them. I took two orange HD buckets, filled both with warm water, and put Dawn dish soap (original formula) in one of them. I have found that the subsequent cleaning with acetone goes much faster if the most of the grime and residue has first been removed by washing the parts with Dawn first. It does not take long for the soapy water to turn pitch black, and I am always amazed at how filthy the parts actually are. Anyway, I set up a wash/rinse routine for the 4 remaining ribs, using a scrubbing sponge with the green scuff pad attached to one side.

I have not yet done this for the main wing skins, and I had not used this method for any of the other larger skins yet. But since I needed to prime a larger-than-normal part of the interior LE skin due to my subskin that will be in contact with the interior of the first bay of the LE, I decided that I would also try the same washing method I used for the ribs. Obviously due to the size of the LE skin I could not dunk it into the buckets like I did for the ribs, but I did use the sponge to wash the interior as best I could, and then wiped it dry with a micro fiber cloth. It seems to have worked well.

Prior to this I realized that I had not yet deburred any of the edges of the access panel holes or the outer edges of the LE skin itself. So I took my edge deburring tool and took care of that. this also raised a question that I will need to get answered from Vans or from someone on VAF. I am not certain if I am supposed to kerf the edges of the skin where they will attach to the main wing spar flanges. I think that I still need to do this, but I need to make certain.

I only question this because these skins are supposed to butt up very closely to the main wing skins and the fuel tank skins. I don't know if kerfing the LE skin will introduce a larger than desired gap between the main skins ant the LE, or if this is still necessary regardless, so that the edges of the skin will lay flat against the wing spar flanges when riveted in place. If I find out that I need to do this, I will need to find my edge kerfing tool from Cleaveland Tools, that I haven't used since I put all the tail feathers together.

Next is a pic of the 4 ribs all scuffed, cleaned, and final cleaned with acetone and a microfiber cloth. when you do multiple parts like this, especially those that need to be assembled in a very specific order, you have to devise a method to keep each part organized, since all prior identifying markings will be removed during the cleaning process. In this case, I kept the ribs organized by keeping them stacked in a very specific order each time I scuffed or cleaned them. I lined them up on the table after cleaning them so that they were in the same position that they will be installed in the LE from left to right. The end rib flanges face a different direction than the rest, so that one is easy to spot. But the others are exactly the same rib, with the same rivet holes and flanges all facing the same direction. Keeping them in order is very important, since even small variations in the match drilling process can make a difference in the final fit of the parts when they are riveted together. After they are primed I will put some tape on them and mark the rib position on the tape.

And finally a pic of the wing skin all washed and ready for primer. After the suds bath all scuffed metal was final-cleaned with acetone and a microfiber cloth (my carcinogen of choice for cleaning metal). I used chemical-resistant rubber gloves to keep it off my hands. These are the long green ones at the bottom of the pic. Also shown are a large number of microfiber towels that need to go in the washing machine so I can try to reuse them. Suggestion: do NOT put these in with any other clothes. Best to keep the airplane building/chemically-laiden materials away from other things, just in case.

Since I will most likely need to use a bit more primer to cover these parts than I did for the last batch, I will plan to use my HF HVLP spray gun, since it has a 20 ounce cup and larger spray area, compared to my touch up sprayer than only has a 7 ounce cup.I think that one full cup-load of primer from the HVLP gun will cover the interior skins and the 4 remaining ribs.

I will probably scuff and prime the entire subskin as well, since I have not yet determined the final form of this part, and I can't really do that until I have this access panel mess taken care of once and for all. One nice thing about living in Denver is that I don't have to worry about surface corrosion very much. So I can leave the scuffed parts till tomorrow, when I have more time to set up the sprayer and everything else that has to be setup for priming.


Till then,

KPR...