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Archive for October, 2015

Finishing Up the Tank Internals

October 30th, 2015 No comments
Capacitive Sender Work Complete

Capacitive Sender Work Complete

Today I decided that I would get the internal tank components as close to tied up and complete as possible. All that was on the list was sealing the inboard capacitive sender connections/wiring, securing the wires in one tank to the vent line, and torquing down the fitting nuts for the vent and return lines.

I purchased a little cup of B 1/2 sealant from my local parts distributor a couple of weeks ago, specifically to do these last little items before being ready to do the “big” seal of the rear baffles on both tanks. The quantity of sealant was more than adequate, and the pot life was just right for hitting these little jobs. I first cleaned up the wires and vent lines with MEK. Then I prepped the work area for sealant (actually was letting the sealant get to room temp), then mixed up the batch.¬†I packed most of the B 1/2 into a medicine dispensing syringe and then started smearing away. As you can see from the above picture, I covered the entire inboard plate connection(s). I have heard that folks have had fuel leak out the BNC connection at the wing root because fuel had migrated through the wire to the post. While I cannot for the life of me figure how a properly soldered connector could permit fuel to leak through a solid wire, I figured a little more sealant over the connectors and wires would certainly keep fuel from wicking through all the way to the connector. Additionally, sealing the connections also adds some vibration resistance and stability. Needless to say, these aren’t going anywhere soon.

Once the sealant was spread and double checked, I turned to prepping the cover plate/pick-up line parts for sealing and assembly. Up to this point, I had simply hand fit them together. I took the protective plastic off the covers, deburred them, and cleaned them up with MEK and re-assembled. At this point, I can seal them together, which will likely happen after completing the baffles (or at the same time).

All that remains is torquing down the nuts for the return and vent lines. I am trying to decide if I should throw some sealant on the threads for this task. It would be a real pain to have to open up the tank to redo these if they ever came apart. I’ve read both ways…which didn’t help. I also need to rig up a system to get the proper torque as well. Some have used highly calibrated hand sensors (brain), others have put extensions on their torque wrenches and done the math. Either should work for me. ūüėČ

Getting real close to a full day of sealant and then no more! SOOOO happy that day is approaching!

Categories: Tanks

End Ribs Sealed

October 12th, 2015 No comments
Right Inboard Rib

Right Inboard Rib

Since today was Columbus Day, I didn’t have to go to work.¬†I committed to doing some real work on the tanks instead.

First up was cleaning all the inboard/outboard ribs, skins, and surrounding areas. I taped off the skin flanges with electrical tape to keep the over squeeze in check. Additionally, I cleaned up the T-405 and T-410 that have to be installed after the inboard ribs are riveted in.

Once cleaned, I mixed up my first cartridge of sealant and put it in the gun and started to go to town. I started by buttering up the inboard rib of the right tank. I put a significant amount of sealant on the nose of the rib to insure good squeeze out, since this is where a good amount of leaking can occur if not properly sealed. After the rib flange was¬†buttered up and the rib was inserted into the skin, I inserted a cleco in every other hole and began squeezing rivets from the leading edge aft, alternating from the top to the bottom¬†sides of the tank. I did have to use my “no hole” squeezer yoke for 4 rivets near the vent fitting and the BNC connector for the fuel senders. Not a big deal, but glad I had it. I¬†used my standard yoke for the¬†rest of the rivets.

Once all rivets were set, I buttered up the back of the T-410 and T-405 and put in place in the leading edge. I had to switch over to the rivet gun at this point to set the AN470AD4-8s (though the plans call for 7’s). I made¬†a mess inside the tank, but got them set. Then it was all about creating fillets both on the inside and over the rivet lines on the exterior and around the brackets. I covered every exposed head and tail of every rivet inside and out. What fun!

Right Inboard Inside

Right Inboard Inside

Not the cleanest work I’ve done, but should be leak free. It’s not easy getting my big hands in these small areas.

Right Outboard Rib

Right Outboard Rib

Once I got all the sealant where I wanted it, I removed the electrical tape and exposed a nice clean edge near the rib flange. I switched gears to the outboard rib. I had already riveted/sealed the T-410 to this rib, so all I had to do was butter up the rib flange and then repeat the same process of riveting as I had used on the inboard rib. Fortunately, since it does not have all the penetrations as the inboard rib, it moved pretty quick. The pace was also helpful as the pot life of the sealant in the cartridge was starting to hit. While it was getting stiff, it was still workable.

Right Outboard Inside

Right Outboard Inside

Prior to inserting the rib, I did make sure that I bent the vent line up towards the skin after it leaves the retainer clip that was riveted on with the fuel cap flange. This will just help keep the line out of the fuel level quicker and keep it from expanding out/draining from the vent line when running the tanks at full and in the Utah heat. Here you can see the vent line as it bends up as well as the fillets on the interior of the rib. You can see the large fillet at the leading edge. It never ceases to amaze me the way that the sealant is SOOO important to a leak free tank. Based on the design of the ribs, there is no other option.

Wire Dabs

Wire Dabs

At this point, I was trying to see if I could still use the sealant and place the small dabs on the wire/vent to hold the capacitance sender wire in place. The sealant was really getting hard to work with and very thick. Once I got these dabs on, I gave up on the rest. I will have to finish the little items with another batch of sealant later.

Once I felt this tank was as done as far as I could complete, I cleaned up the tools, got rid of all the gloves, rags, popsicle sticks, etc., and then restocked/reset and repeated the process on the left tank.

All in all, it was a good and very long day out in the shop. Next up will be to finish the wire dabs and terminal sealing of the capacitive plate connections and then prep for the rear baffles. These parts will soon be tanks and able to be tested for leaks (they better not). I can’t wait to be done with this stinking sealant and tight places. We’ll see what the next build session yields.

Categories: Tanks

Capacitive Sender Wiring Complete

October 3rd, 2015 No comments
Right Tank Inner Capacitive Plate

Right Tank Inboard Capacitive Plate

Can it be true? Did he work on the plane?!?

It sure is. I sure did.

I had a good day in the shop cleaning up some items, working on a couple of other projects, and while dancing around the tanks on the bench, decided to finish up the attachment and wiring of the capacitive fuel senders. It’s been almost 17 months since last working full steam on the plane. Life certainly has its way sometimes of setting priorities for you.

So…where are we?

I needed to install the outboard plate in the right tank, and the inboard plates on both tanks. I decided to work on the inboard¬†of the left tank first. I needed to find the appropriate length of both wires and then trim them to final. Once this was done, I thought…”how in the world am I going to get in here and strip these for the connectors?” Then I realized that stripping the wire was going to be the easier part. Make sure to leave a little slack on the wires. What is extra can be wound around the vent tube to remove that slack later. Getting the connectors on would be much more difficult. I was able to get my quality wire stripper on both ends with surprisingly little trouble. I purchased and use the IDEAL Stripmaster¬ģ¬†¬†sold by SteinAir. Pricey, but worth it. It does a perfect job of cutting the insulation to the correct profile as “required” by aviation standards.

Once the insulation was stripped, I tried to figure out how I was going to use my cheapo wire terminal crimp tool to securely get the terminal ends onto these short and somewhat tight spaces for these wires.¬†My cheapo tool was really made for a kid doing a science fair project. I’m not sure why they are even sold. You first have to crimp the wire portion with no indication if proper squeeze. Then you have to crimp the insulation side with no real proper slot which can actually ruin the connection. I think I may actually toss this tool (or give it to my sons).

el Cheapo Crimp Tool

el Cheapo Crimp Tool

 

Fortunately the wire for the outboard plate can be unwound from the vent tube and better access is possible. The BNC to inboard plate however is not so giving. I decided to run out to my local electronics warehouse for a lunch break and get a quality ratcheting crimp tool. I have been¬†meaning to for some time, but hey…I had a good excuse to go get another tool. Fortunately the store had one, and they were willing to match the lowest price I could find.

The Correct Crimp Tool

The Correct Crimp Tool

Though still tight, the above tool was able to successfully get into the limited spaces and offer a one stop crimp with a single motion. The beauty of this type of crimp tool is that it does both the wire and insulation crimps simultaneously. The ratcheting action also allows for proper squeeze as it will not open again until the proper depth as been reached. I was able to get the connectors inserted into the tool, close until just starting the squeeze, position the wire in the connector, and then complete the squeeze. One and done.

Left Tank Inner Capacitive Plate

Left Tank Inboard Capacitive Plate

After completing the crimps of the connectors, the last step is to attach them to the plate. This task is frankly better suited to a Russian Child Contortionist. Once the screw is inserted on the inboard side of the plate, getting the plate in a position where one can both get a screw driver on the head, and a wrench on the nut on the other side is something of a puzzle. Toss in my larger hands and the tight space, I was left thinking for some time and trying MANY angles. I was able to succeed on the left tank after some real time spent and some frustration.

Once complete, I ran the right tank outboard plate/wire and repeated the wiring chore for the inboard plate. As you can see from the top picture as well as the one just above, these are nicely installed and secure with good wire strain relief on both tanks.

As I was prepping for the contortion task repeat for finishing the wiring of the left tank, I caught a glimpse of a tool that would have made attaching the connectors to the inboard plate of the right tank SOOOO much easier. In using it on the left tank, I was right.

Essential Tool for Finishing the Capacitive Fuel Senders

Essential Tool for Finishing the Capacitive Fuel Senders

If you don’t have one, get one. I have two. They are perfect for tight spaces. One side accepts standard screw driver bits, the other has a socket for a 1/4″ drive socket wrench handle. This one saved a considerable amount of contorting when completing the connection to the inboard plate of the left tank. Mine are from Craftsman, and if I remember correctly, Sears may have just given them to me as part of a promotion. GO GET ONE or a set!

Right Tank Wires

Right Tank Wires

Felt good to get these steps out of the way. Next up is sealing and riveting of the inboard/outboard ribs. At the same time, I need to seal the inboard connectors to the plates and seal up the wiring connections. I also need to dab sealant every inch or so on the wires wrapped around the vent tube. Then…if all goes well…I’ll soon be closing up the tanks FOREVER!

Categories: Tanks