Removed Fuel Senders

 I can't sleep and it's too late to do anything else, so I'm updating the blog.

My daughter & her family are visiting, plus I'm still working, plus we're going to try to go the Thunder over Michigan airshow tomorrow so I haven't had much time to work on the plane.   I happened to have 30 min to myself before going to work yesterday so I pulled off the leaking fuel level senders from both tanks.

Mounting location of removed R fuel level sender

As you can see, this doesn't look very uniform.   From 10:00 to 14:30, the darker and somewhat smooth color is fuel tank sealant that never even touched the base of the sender.   No wonder it leaked!  The lighter area is where there was some adhesion to the two pieces of metal and I had cut through it. Next session, I will clean that all off down to bare metal before trying again.

Curiously, there was no adhesion to the brass colored metal of either fuel sender.   I will really scuff up those surfaces, too.

Of course, to clean the inside of the tank and remove the debris from this process meant that I had to remove the inboard fuel tank access panels, too.  Those had been sealed with fresh fuel tank sealant and the showed proper, evenly 'wetted' distribution of the sealant after I got them cut off.  That made me feel better that I can apply things evenly if I'm using fresh sealant.

Both tanks, with senders and access plates removed. 

Good night.

§25 -- inboard mixer boxes

Section 25 is the inboard mixer boxes.  These were almost as easy as the outboard ones, but there are a few differences; mostly just a few more parts.  That made it a bit more complicated to ensure that I had the correct orientation when I built the other side, as I have a somewhat difficult time with L/R spatial orientations.

One trick published in VAF was to mirror the PDF images from the KAI in software.  Several VAF members have gone so far as to print mirrored pages of the whole book, but that's overkill.  I did something that was fast & cheap and just took quick pictures w/ my phone of the relevant pages.   10 seconds of editing on each page to mirror each one and I was in business.  Having just built the left version, I didn't need to refer to the printed notes very much and I concentrated on the object I was holding and comparing it to the image on my phone.  In the future, I'll use my iPad instead because of the larger screen and its attached stand.

Remember the NAS1097 rivets I talked about the other day?  I said that there were only 4 in the whole kit.   Wrong.  There were only four of the AD3-4 and I totally overlooked the bin that held 36 of the AD3-3.5's.  Those were the size I was supposed to use earlier.  As a result, when today's kit called out for the 3-4's I had none.  I elected to use AN426AD3-4's to achieve the proper length and deal with the larger head by accepting the larger countersink needed to flush the larger head than the called out AN1097.  The primary advantage to the 1097 is the ability to be used in very thin material, but the piece that accepted the rivets in question is quiet thick-- 0.063", so I ended up with something stronger (not needed) and the correct length.

Inboard Mixer Boxes

BTW, I'm determined to provide my grandson an early introduction to the project.  He just turned 8 and has a very short attention span, but I did manage to show him 5 different rivet setting techniques before he timed out.  Baby steps! :)     I have 3 granddaughters visiting later this week.  One or two of them may be interested, too!

Layne, learning about squeezing rivets

§24 Left

Like building the outboard mixer box itself, installing it into the rear spar was relatively straightforward.  It involved being very careful about which rivets were installed into which holes, since the structures had multiple pieces of varying thicknesses.  There were a lot of rivets that had to be driven, including some where it is really difficult to get your hand in place with the bucking bar!  I'm very glad I spent the money on the tungsten bar -- its small size came in handy for just this occasion.   I suspect I will never need another bar that doesn't have a unique shape/size.  (There are bucking bars for sale specifically for doing some hard to reach rivets in the tail cone of the RV-14.)

I took a picture, but it's not worth publishing because it looks just like the last one of the rear spar & ribs.

§23 -- outboard mixer boxes

Section 23 is a very short, straight foward chapter that builds the Outboard Mixer Boxes.  It's literally just installing 1 nut plate and riveting 4 pieces together with 16 of the easy-peasy pull rivets.   It took me about 2 hrs to do both L and R sides.

I decided to do them both because I do have a lot of trouble with mentally mirroring the drawings.  I built up the Left in its entirety, then set up the parts for the R and used the physical structure as my mirror source.

I learned a little bit about rivets.  The kit calls out for a very specific rivet, NAS1097AD3-3.5 rather than the much more common AN426AD3-3.5.  In fact, the entire wing kit has just four of the NAS rivets.  They are to be used in shear loads only, as they have a very small head and won't resist much axial loading.    They are typically used in very thin material.   What's odd is that Van's almost always called out the AN426's for similar applications and the material in question was actually pretty thick, 0.050", so I have no idea why they went to the trouble of stocking these specifically.  Oh, well.

L & R Outboard Mixer Boxes

Leaks identified

While working on the R spar, Marc came over to help figure out the tank issues.  He's also an engineer and I wanted a fresh pair of eyes on the problem.  He agreed that there should be no leaks based on my procedure and his visual inspection.  Back to testing: we split up the tasks of one person pumping and the other spraying bubble soap, but never saw any bubbles.   We finally took the compressor and blew air into the tank.  We could feel a breeze on our fingers on the inboard edge (with all of the connections) but couldn't make any bubbles appear nor feel our way to the leak.

Rather than using expensive, toxic, smelly and flammable avgas I decided to do an old fashioned test.  We filled the tank with water from the hose.  Viola!  The Proseal around the fuel sender leaks like a sieve!  Water streamed from the entire circumference.  Mystery solved.

This also validated my gut feeling that it was a systemic issue.   Recall that I used left over Proseal that had been in the freezer.   While working with it, it was appropriately sticky and gummy and I thought it was OK, but apparently it was by then too viscous to actually flow when I tightened down the fuel sender plates.

I'll order some more Proseal (or B2 sealant as it is now known) and re-do the senders when it arrives.  I'm feeling much more optimistic that we'll get something that is water tight next time.

§ 22-4 thu -17 Left, -18 thru -21 R

Got lots of building done this weekend.   The rear spar is the topic of construction for the next 4 or 5 chapters.  § 22 is pretty straightforward, if somewhat long.  I was really hoping to be able to complete the entire L rear spar on Saturday, but ran into a minor glitch.    

If you notice the title, I suddenly switched from building the L rear spar onto building the R rear spar.  Curious, no?    Page 18 calls out starting with W-15016B-002.   That's odd.  a -002 part implies that you've probably come across the corresponding -001 already.  I proceeded until I came to the conclusion that I had indeed built the corresponding assembly (outboard aileron attach point) for the other side.

No problem, I thought to myself.  I went to the parts shelf but for the life of me, I couldn't find the expected -001 part.  My inventory sheet shows I had it in my hand at one point, but neither myself nor my wife could find it in the shop.

I'll order another one this weekend and will eventually get to finishing the L rear spar, but during the meantime, there's other stuff to be done so I'm not stuck.

most of the L rear spar

Quick update

Just a quick update so you know I'm still here.

I've laid out the parts for the next section and feel pretty good that it will come together quickly in the next day or so.   

I finally received the last few back ordered parts from Van's.  My wing kit is now officially complete.  

There is much gnashing of teeth on VAF regarding some misaligned holes on a few wing spars.   Those spars are apparently ~$3K each!   I dug mine out and clecoed together the areas of question and the holes are well aligned, so I don't have to deal with getting Van's to replace them.   

Marc is a partner in the Cirrus and we're going to go flying tonight.  Tomorrow, he's going to swing by the house and I'll enlist him in helping me find the source of the leaks in the tanks.