Started prep work on wing skins

 Steve & I bucked 6 rivets holding one of the nose ribs.  That officially completes page §29-11 R.  Still waiting on the missing rivets to finish off the entire section, but I'm sure they'll arrive eventually.   By the way, I didn't show you a 'big picture' of the current organization of the workshop.   Here you go!  On the right are both of the wing assemblies.  They are 'backwards' from this point of view with the Left wing on the right, and vice versa. From here, you can't see the clecos that are still in place.   The work tables are now freely accessible and ready to be used in prep work.

workshop with cleared tables

I finished §31-05; prepping the bottom middle skins.  (The inner skins are pre-assembled as part of the fuel tanks).  On paper, this was very simple—attach a dozen nut plates to the access holes.  In reality, it took about an hour to do each skin.   Firstly, there's an awful lot of surface area which means that there's a lot of the protective blue plastic that must be pulled off.  For small parts, it's easy.  For these guys, I was actually getting painful finger tips from pulling and then peeling off the adhesive.   Life got a bit better when I borrowed my wife's hair dryer and heated up the surface as I went.

Secondly, there's a lot of linear edge that needs to be deburred.  The pieces are too large to hold and run by the scotch bright wheel on my bench grinder.  They are way too big to use the tiny Dremel wheels.  I had to drive to the Aviation Division of Roush Hardware and pick up a scotch bright wheel that I then put in a hand drill and could finally deburr the edges with something like efficiency.

Thirdly, some of the edges need to be "broken".  When two pieces of sheet metal are riveted together, the top piece can have a tendency to have its edge bend upward slightly due to the compression of the nearby rivets.   To counter this, the appropriate edge is 'broken' with a downward flare before being assembled.  I happen to have an outstanding custom built tool for this purpose.   It's a pair of vice grips with the jaws replaced by steel rollers, one of which has a nice tapered flare.  I just roll it along the correct edge and it produces a clean, uniform break.

[I will take some pictures of the broken edge and tool  and edit this post to include them the next time I update this blog.]

right lower middle wing skin 

resting on top of the right wing assembly

§29-09, -13 & -15 Right. most of the R nose ribs

Still making progress.  I prepped all of the nose ribs and riveted 11 of the 15 total.   I also did 80 % of another page, but I can't mark it complete until Steve comes over tomorrow to help me buck a set of rivets that are impossible to do by yourself.   After that, I'm at a work stoppage for both wings with respect to completing section 29 until I get a shipment from Vans.   I placed the order last Sunday and got crickets for 4 days.  Yesterday I sent a nice note asking "when?" and explained that I could either wait or change gears and tackle something else.  They promised that I would be a priority on Monday.  We shall see.

both wings with all ribs attached (but not riveted)

Tomorrow, I plan on doing the prep work for installing the skins as per section 31.   Putting in the wiring harnesses from section 30 can absolutely wait until the skins are actually attached and they shouldn't take more than an hour. (Hah!  Where have I heard that before!)  Hopefully the wayward parts will arrive by the time I finish prepping the skins and I won't have lost too much time.  If not, I'll set the wings aside and start on the tail feathers.

Yesterday I caught up on reading the forum and came across a bit of intelligence that Vans is not expected to take orders for the next kit until November and shipments won't be until after New Year.   That means that I will almost certainly be done with both wings and the tail feathers before I get another shipment.  While frustrating, it is also somewhat calming in that I no longer have that nagging feeling that I should be spending all of my free time in the shop.

To that end, my darling wife gets off work in 5 min.  She's going to change and put on make up and we're going out on the town on a Saturday night!  

§27 R, $28 R, §29-5—7 R -- Main spar attached, push rods installed

 Another really productive day.  It wasn't all roses, but it was very productive and enjoyable.   Bottom line—the two wings are essentially at an equal state of assembly! 

For the record:  §27-05, -06, §27-08, -09, -10, §28-13, -18, -19, -20, §29-05, -06, -07

Section 27 was started the day before yesterday (I played hooky yesterday and went flying.  More about that below) and really is just riveting the flap mixer to the rear spar/tank.  This is where the famously expensive Cherry Max rivets are used.  These puppies can be used in lieu of driving AD470's in almost all locations, but Van's cheerfully lets you ensure you find the correct length and you must source them yourself.  Apparently there was a fire at the factory that made them and now they sell for ~$2 a pop! Ouch!   As much as I'm tempted in a few places, I'll pass for those prices.

I jumped ahead (§29) and attached the front spar to the tank and clecoed it to all of the loose ribs that would otherwise be hanging in the breeze.  This gives the assembly a significant increase in rigidity and makes me feel better about picking it up and moving it, etc.   Prepping the front spar involved riveting an extension to it using a doubler.  Those were all driven 470 rivets and, because access was easy, it was actually fun.

Front Spar clecoed in place

Section 28 involved finishing up the push rod that I had to set aside a few months ago when I spilled some loctite onto a bearing and decided I didn't want to use it.   When I went to find the replacement, I spent 5 panicky minutes searching before I realized that the smart place to have put it was in the parts bin supplied by Vans.  Yep, there it was.   The rest of that chapter was taking the previously manufactured bell cranks and figuring out which way was which and getting them installed.  Rather than last time, when I wished for a trained capuchin monkey, I discovered I could attach a push rod to a bell crank out in the open, then insert the bell crank through an access hole and into position. Much easier!

top view of the R outboard (aileron) mixer

Looking inboard, under the fuel tank top skin, 

at the inboard aileron  pushrod 

At this point, I could sort out the D-cell nose ribs and cleco them to the front, but I can only attach 11 of the 15 as I am waiting on LP4-4 rivets from Vans.  I'm also waiting on the plastic clips for attaching the wiring harness.   Essentially, the wings are at the same place and both stuck.

Steve Brown will return on Sunday to help me drive the awkward rivets for one of the nose ribs, and I'll attach what I can.  I have enough saw horses and work stands that I can actually move both wing skeletons off of the work bench.  That will give me room to start prep work on the skins so that when the errant parts arrive from Vans I can get right to work installing the skins.  That's going to be 2 or 3 days of long, tedious but FUN work!

(I played hooky yesterday because the weather was just too good to pass up.  I managed to get out to Marysville and fly the Citabria in moderate winds from about 45° off the runway.  I'm nowhere near feeling comfortable landing that plane and it was a good workout.  Surprisingly, I made 4 very good landings on the grass.  My technique wasn't really 'full stall' nor 'tailwheel'.  I was too busy not loosing control to think about classifying them.  I flew the Cirrus and did a set of engine verification procedures.  For the curious, they are called "GAMI spread determination" and "LOP mag checks."  Both went well.  Finally, I took up the RV-12 just to say I flew all 3 aircraft for which I am current.  I didn't fly the CAF PT-26 because (1) I'm not current, and (2) it has a bad mag and is grounded.)

§22R, § 24R& §26R ! -- Rear spar and main ribs

 Wow!  Today was a very productive day.  It didn't start out that way.   My work/sleep schedule is truly chaotic.   I didn't feel much more tired than usual when we went to bed last night but I slept 12 solid hours and had no bouts of tossing & turning.  I woke up around 1pm, but puttered around the house and didn't even get dressed until almost 5pm.  (I might have been a touch hung over, but we won't talk about that, will we?)

In my last post, I was undecided about how to proceed.  I decided to build up the skeleton of the right wing in parallel and will then proceed with applying skins to both wings.  This way I have the open, accessible L wing to use as a reference for the R since there aren't any drawings of the R wing.  I had already purchased two portable work stands from Home Depot and Lada helped me move the L wing skeleton to those to get it out of the way and make room for the work on the R wing.

Despite not getting started until 5pm, I managed to finish 3 chapters for the Right wing!   Much of that speed was due to having already built up the mixer boxes and aileron brackets for the right wing a couple of months ago.  Today, I attached all of the main ribs to the rear spar, attached the outboard mixer box to the rear spar, and fastened the rear spar to the fuel tank.   In detail, I completed the following pages: §22-04, -05, -06,  -12, -13, -14, -15, -17, -22, -23, -24, -25, §24-05, -06, -07, -08, -09, §26-05 & -06.

Foreground: Right wing rear spar assy

Background Left wing assy

Right wing rear spar assy

I have tomorrow & the next day off.  I expect that I will be able to install the inboard mixer, finish the pushrod and install it, and then attach the main spar & D-cell nose ribs.   That will bring me to par with progress on the Left wing.  I'm waiting for parts from Van's to finish the D-cell Nose Ribs, so I might end up in a work-stoppage until those parts arrive.

§29-08, 10, 12-15, 17 Left

 Argh.  I was really hoping to finish off this section.  It's all about attaching the grommets and tie-wrap clips to the D ribs and riveting the ribs to the spar.  Surprisingly, it was the riveting of the plastic tie-wrap clips that was problematic.    5 of the 15 clips didn't hold up to the pressure exerted by pulling the pop-rivets and they ended up getting ruined.   While I could have stolen from the supply designated for the Right wing, the rivets that are called out are LP4-4's, not -3's.   I literally have thousands of -3's, but the supply of -4's is actually only half of what is needed and there aren't any surplus to borrow from.  As a result, I'll have to wait until replacements arrive from Van's before I finish out this chapter and move on to installing the wiring harness.

Ruined tie-wrap clips and LP4-4 rivets

I'm getting close to making a major decision.  Should I continue on the left wing alone, set it aside and then do the right wing, OR should I set the left wing on saw horses to use as a reference and build up the right wing skeleton, and then proceed to put skins on both of them?   I need to decide in a week or so.  Keep reading.

§21 addendum complete, Left & Right

 After 6 weeks of being stuck in the doldrums of sealing the tanks, I have resumed actual construction.  Van's issued an addendum to chapter 21 instructing me to install a bunch of nut plates on the tanks.  Since this had nothing to do with their fuel integrity, it didn't cause much headache.   One set of nut plates is around an access hole on the bottom of the skins.  That took some gentle skill because I had to mildly contort myself in order to see what I was doing and I needed to balance a 426 rivet on one die of the rivet squeezer, then thread the rivet through an upside down hole and finally squeeze it in place.  I only dropped 4 of the 48 rivets that were set that way.

Access hole being equipped with nut plates

The image above probably needs some explanation.   The bulges at the top of the image are the outboard skin of the Left fuel tank.   There's about 18" of skin both above and below the tank and we're looking at the bottom skin with its access hole.  In the foreground, you can see nut plates and set rivets.  in the background are the clecos securing nut plates that have yet to be riveted in place.   This is where I was having to balance the rivet on the squeezer and gently raise it into the open hole.  It was actually a lot of fun.

Airworthy fuel tanks, finally! §21 complete for L and R

(Mea culpa:  I wrote this 4 days ago and never hit the "Publish" button.  Doh!)

The fuel tanks are officially "done."   While I never was able to get them air tight, as some VAF members have been able to do, I have been successful in demonstrating that they would hold water and as of yesterday, that they could hold 100LL.

(recap) As you may recall, I spent nearly a month trying to get the fuel tank sensors installed correctly and without leaks.  The first few attempts were definitely learning experiences for me because it was obvious that I had done a poor job.  Each one got better (e.g., the residual leaks were smaller & slower).  I finally got the obvious leaks sealed and then proceeded to pressure testing.  There were some dumb leaks that were easily corrected, but then I really got serious about trying to make them airtight.   

I gave up on Van's idea of using a kid's balloon because there were some very thoughtful and data supported comments from VAF that it's an exceedingly poor gauge and should best be thought of as a pressure 'fuse' that will blow if you end up putting too much pressure into the tank.  Instead, I bought some clear plastic tubing, added colored water and used that as a simple manometer.   15 inH2O = ~0.5 PSI and is roughly double the pressure of a full tank of fuel, so I figured that would be a good value to use.  Unfortunately, despite everything I could think of, I could never get the tanks to hold pressure for more than 30 min.

I suspect it's the fuel caps that are leaking.  I couldn't prove it, but I just don't like their design.   I even tried sealing them with condoms, but could never find a leak nor maintain pressure.

Lada & I filled them with with water and left them to soak for a long weekend.  No leaks!    100LL is half the viscosity of water, so there might be a hole too small for water to leak through, but might pass avgas.  I drained all of the water and borrowed 29 gal* of 100LL from the Cirrus and tried it again in the Left tank.   Success!  I managed to salvage about 28 gal and put it in the Right tank.  Another success!  Neither tank had any visible moisture after 24 hr of containing 100 LL.

This officially completes section 21, as it was published on the day I received the wing kit.  More about that later!

*I have 3 jugs of 8 gal each that I use to buy premium auto gas and pump into the RV-12.  I also have a 5 gal container.  Together, they are 29 gal. The fuel tanks are 30 gals, so "close enough."  If there's a leak at the very top, it will not be operationally important because fuel won't leak up against gravity.  In addition, aircraft tanks are rarely stored in a completely full state.  I will take pains to ensure that the plane is not parked outside during rain, or will find a way to cover the fuel caps if needed.