Major progress! (Minor setbacks)

 It's been over a week since I published, so let me bring y'all up to date. 

Progress

§29-08 R, -10 R, -12 L & R, -14 L & R, -16 L & R —  completion of the nose ribs

The tie-wrap clips finally arrived and I was able to finally finish the Left wing and do the entire Right wing in about an hour.  Recall that I had problems with getting the rivets to properly set.  There was a suggestion to use a small washer to reinforce the thin metal of the rib, but that didn't work.  That was my only spare, so I went with a more fool proof method of using #6 nuts, washers & bolts.  These had the advantage of being removable.  Later, when I was running the wiring harnesses, I realized that the tie wrap clips on the outside 2 ribs are attached at the rear of the lightening hole and not the front.  Had I riveted them in, I wouldn't have been able to correct my overside.  Anyway, §29 is done.

§30-05, -06, - 07,  -08, -09  Left & Right — Wiring harness

This chapter is the placement of the wiring harness.   It was very straightforward and took about an hour or two.  As mentioned, I needed to reposition 4 of the clips, but no other complications.  

Left wiring harness

§31-05, -06, -07, -08, -09, -10    — Wing skin preparation

I've been really looking forward to putting on the skins since they are what transforms a collection of spars & delicate ribs into a structurally sound and clearly recognizable wing.  These pages were all about prepping the skins.  Nothing conceptually difficult, but lots of labor.  Each page represents two skins that needed to have the plastic removed, edges deburred, some edges 'broken', and nut plates riveted on.  Pretend that there's another page for the single skin that didn't have nut plates to be added, so it doesn't even have a page to represent it.

me, marking a part number on a 

part as I remove the plastic film

§31-15, -16 -17 L & R    — Clecoing top skins into place

The top skins got placed before the bottom skins since the wings were already right side up and I didn't have anybody to help me flip them.  The stiffeners went in easily and the skins attached without a hitch.  I put a cleco at every intersection of a rib and a stiffener. Those are essentially the load points in flight and the clecos will be able to support the wing when inverted to work on the bottom.   Unfortunately, I forgot to take a picture of my handy work.

§31-18, -19 L & R    — Light Bracket

Man, by this time I was flyin'!   Translation:  I was working so fast that I got sloppy.   On each side is a simple bracket (same on both sides) and a truncated nose rib.  I missed the fact that the bracket is symmetric L vs R, but isn't symmetric Up vs Down.  I also missed the fact that the -002 rib is called out on the L wing because typically the L side gets the -001 variants of parts.   Anyway, those got assembled and riveted in without double checking.   The next day I looked at one of them and realized that there was no way that a skin was going to go over and get fastened properly.  By this time my son-in-law, Dennis, had come over to help so he got a lesson in drilling out rivets and backtracking your work to see where you screwed up.  He helped install the rebuilt brackets and then we were able to flip the wing onto its back.

light mounting brackets

Lighting bracket in place on the R wing

Obstacles

Pitot tube mounting bracket.

I thought I had a W-00039-001 and a W-00039-002 (mirror image parts), but discovered that I have two of the -001 variants.  I've written to Vans to get a replacement, but the web store shows 30-60 day backorder.  Luckily, it's something that can be installed at any time in the future.  In fact, I might not use this one as it sounds like Dynon has a different mounting system.

Rib interference

When I placed the left lower mid skin on the assembly, I noticed that there was rib that was obstructing the opening through which the wing strut would attach.  I verified that things wouldn't fit and decided to just shut down the shop because I was tired and had been working hard and fast.  I know from personal experience that if I kept going to find my own fix for the problem, I'd likely make something much worse or fail to realize that there was a reversible error in previous work.

Rib underneath the slot in wing skin

Luckily, I was able to find a simple explanation & fix.  Per the RV-15 Wiki, there was a design flaw in the rib in question and it was made with the same tabs as the rest of the ribs, but the tab shouldn't be present in this location.  I presume they modified the part after I got mine.  Vans says to just cut the offending material out as they won't send a replacement.  They advise that you do that before you install it.  Oh, well.   

That's it for today and probably for the week. It's a busy work schedule and I doubt I'll have time to get into the shop for the rest of the week.

§29-17 R, §31-06 L. problems w/ tie clips

 Well, it was the usual "2 steps forward, 1 step back" kind of day.  I received a shipment from Van's, but it only had the LP4-4 rivets that I had ordered, but not the replacement tie wrap clips for the ones that I had ruined the other week.  I sent off a note to Vans asking for an explanation and/or a shipment.

I was able to attach the 3 remaining R nose ribs with the new rivets without any problem.  On the other hand, when I went to attach some clips to the remaining L ribs that needed them I had 4 consecutive failures.   For some reason, the tips (shop heads) of the rivets just aren't getting a good grip on the rib and they pull right through and then expand inside the plastic clip.  I tried using the hand puller, and both low and high pressure on the hydraulic puller but it just isn't working.   I then tried squeezing some 470AD4-7 rivets, but the rib is curved where the rivet goes and I couldn't get it to squeeze squarely.

2 of today's 5 ruined clips

I think I know what's going on.  Rivet holes gets punched at the factory using a tool and matching die.  These wear over time so there is a subtle drift in the dimensions of the resulting hole.  In this particular case the hole in question is punched into a spot that is then stamped into a curved shape (to provide strength around the lightening hole).  I suspect that I have a batch of ribs that were punched slightly larger than typical and then the stamping procedure stretched them just enough that the rivets don't get a good bite as the are pulled and expanded.

I posted my plight to VAF and 2 other builders reported similar instances.  One gentleman used an idea that I was already thinking about -- using nuts & bolts.  I'll also use some lock tight to secure the nuts.   I'll get some at the local hardware store and finish up putting the clips on the left wing wait for the missing clips to do the right.

Going back to prepping the wing skins, I finished unwrapping, deburring, edge breaking and installation of the nut plates to the lower outboard wing skins.

nut plates held with clecos, 

prior to squeezing flush rivets.

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.

Water tight. Not air tight, but water tight.

 I bet y'all thought I had quit and walked away.   Nope.   Thought about it a bit, but nope.

Both tanks remain stubbornly not-air-tight.  I was extremely hopeful that the through-bolt locking mechanism in the cap was the culprit.  I tried sealing the caps with rubber gloves, but there aren't any more latex rubber gloves and nitrile gloves don't have that stretch that is needed to make a perfectly smooth sealing surface.  They tend to fold and bunch up and that makes them leak way more than the cap by itself.  Condoms, on the other hand, are perfectly round in cross section and can be made to fit over the cap.  It typically took 3 or 4 condoms getting torn to lock the caps in place without damaging the condom itself, but I got good at it.

Still, the damn tanks wouldn't hold pressure.  I gave up on the balloons as pressure gauges and got some clear plastic tubing and food coloring to use as a simple manometer.   15 inH2O is about 0.5 psi and so I used that difference in water height as my pressure gauge.  Pumping up the tanks to 15 inH2O resulted in a drift down to about 1 or 2 inH2O in half an hour.  This was fairly repeatable.    Despite being repeatable, I could not find where the air was leaking using the soapy bubble water trick.  (Which is messy, by the way.  At some point, I'm going to have to haul the wing assembly out to the drive way and hose it off.)

I posted my plight on the forum and, man, did I ignite a firestorm!  Two suggestions were worth merit: one was that I had not accounted for the heat of compression and that the declining pressure was actually the heated air cooling off.  The second was to use dish soap rather than kid's bubble soap for my leak detection.   Both of these have been filed for potential future use.

Several commentators had used the logic of "it's a fuel tank, not an air tank" and simply filed their tanks with 100LL fuel and looked for the tell-tale blue stain.  Other's commented that that takes too long to see the stain, and others said balderdash and basically it turned into a debate similar to the holy war of priming vs not priming.

I like the pragmatic approach exemplified by the "it's a fuel tank."   I did a full up water test over the previous weekend.  Literally.   Lada & I filled both tanks to the brim with water and then left for a 3 day weekend.  Upon my return, there was no damp or wet spot on any of the sides or the tops.  I couldn't check the bottoms because of the weight of the water itself, but if either tank develops a leak on the bottom, I can repair those even after the wings are mounted on the plane.

Last night I drained the water and fetched 29 gal of 100LL from the airport.  I didn't have the correct hoses to configure everything (I can't use the cheap PVC tubing with 100LL, so I have to go to the hardware store for the proper fuel hose.).  I'm going to fill each tank and watch for 24 hours.  If no leak, I will declare them airworthy and get back to actual assembly.   This final step will probably take another week or so.  Stay tuned.

still leaking.

 I finally ended up using a condom to seal the fuel cap on the Left tank, but alas, the tank still leaks.  I have this weekend off work and will spend the majority of my time searching for the remaining leaks.  The good news is that the fuel sender and access plates are air tight.  The bad news is that he fuel sender and access plates are air tight...  :-(

might not be so bad after all.

 I have to admit I was pretty bummed the other day.  I really thought that I had a decent chance at not having the fuel float assembly leak.   Maybe I'm still in the running.    I had to walk away for a day to get over my funk, then worked a 24 hr shift, so I didn't go out to the shop until last night.  The kids came over for Labor Day family get together.   Travis is my son-in-law who happens to be an HVAC technician.   As he puts it, "I chase leaks for a living" so he followed me out to the shop and we got to work.

I pumped up the tank to bout 15 cmH2O and the balloon ballooned.  (That's still so weird to watch Starling's Law in action!).   Travis spent about 30 seconds listening and immediately found two leaks. (I have presbycusis and even wearing hearing aids I couldn't hear a thing.)  I  One was the 6D nipple upon which I had attached the balloon. Although I had  applied thread sealant, that didn't work as well as I thought.  That got capped with the appropriate 6D cap and we repressurised.   It still started dropping, but not as fast.   Travis then noted that I had left the bicycle pump on the Schrader valve and pointed out that's just a friction fit and is a likely culprit, so that came off promptly.   Tried again;  still dropping but again dropping more slowly.

The fuel sender seal had no soap bubbles, so that made me hopeful.  I soaped up the fuel filler cap and found a nice leak at the shaft that goes through the cap from the latch to the nylon lock nut on the inside.  I put some thread sealant on it, but it still leaked.  We called it a night and I slept much better even though I haven't proved the L tank is pressure tight.

 

Tiny bubble in the center of the cap

Today, I'm at work and I just did some searching on VAF about this topic and found the following gem, which I'll try it tomorrow night when I get home from work!

 Old trick but for those have never heard it before: Put a rubber glove inside the fill port before installing the cap. That will seal and isolate the cap.

Well, damn.

 4th time was not the charm, either.   Last week we went on vacation. Before we left, I used an extra thick layer of sealant and specifically embedded the star washers and electrical lug in sealant and then covered the stack.  I had such high hopes.

After we got back on Tuesday, I got some clear 3/8" hose to use as a manometer and hooked that up to the Left tank.   I pressurized it to about 13 inH2O which is around 0.5 PSI.  That was the pressure at which the balloon inflated.   I left it overnight and was really disappointed the next morning as the balloon had deflated and the manometer showed only about 1 inH2O.

I haven't had the time nor the heart to try to find the leak yet.  I'm really hoping it's from the filler cap, as that is considered acceptable by Van's.    I really need to get the tanks sealed because I am essentially at a stand-still until they're done.     Alternatively, I might buy another table and start working on the tail surfaces while debugging the tanks.  Stay tuned.

Empennage kit unpacked & inventoried

 Lots of grunt work involved in unpacking Van's kits!  The other night I unpacked and inventoried the major items and was very happy that none were missing.  It took a little bit of creative engineering to find places to store everything in the garage / shop, but it's all on shelves or standing behind other shelves.  I will need some help taking down parts of the empennage kit to get to the R wing spar, but that's a solvable problem for another day.

Today I inventoried the "small stuff".   The shipping company didn't pay attention to the "UP" arrows on the crate and it was actually on its side on the first day they tried to deliver it.   As expected, a few of the small parts shifted in their parts bin and were in the wrong bins.   it only took about 30 min to sort everything out and I can't complain too much more than I already have.    

EMP Bin #1 -- lots of 'small stuff' !

I'm about $6 short in parts that weren't in the kit.  I'm not even going to 'claim' them, I just put them into my cart for my next purchase.

Cutting up the crate for disposal was by far the most difficult part of the process.

Cut up crate parts & a pile of sawdust

3rd time was not the charm 😤

 Well, I had high hopes.   As my flight partner, Ed, often comments: "Hope is not a strategy."   Despite pre-smearing the adhesive on the mating surfaces, both tanks continue to leak.   The good news is that both are leaking in exactly the same place -- the electrical connection at the top right of the fuel senders.

Bubbles, Bubbles, everywhere! 😩

Since both tanks leak at the same place, and that place is where there are 3 stacked components, I clearly need to up my game in that location.  On Tuesday, I will pull off the fuel senders and the inboard access ports (again; for the 3rd time).  On Thursday, I will make another valiant effort to get these damn things on and air tight!

This time (next time?  Anyway, on Thursday) I'm going to repeat the technique of pre-smearing sealant on both of the mating faces.  I will then insert the screw for alignment.  I will place the first star washer on the screw and coat it with sealant until it is completely 'submerged' in the goo.  Then goes the electrical lug which will again be 'submerged'. and finally the 2nd star washer and its immersion.    Finally, I will place an absurdly large bead of sealant on one of the faces and finally install it.  Hopefully, that will be the final time.  

§22-08 thru -11 Inboard Aileron Bracket Assy Right

 Somewhere along the way, I lost a W-15015A-001 and couldn't finish the remaining aileron bracket.  The part was reordered and arrived last week.  It was pretty straightforward to press the bearing into the bracket and then rivet together the rest of the pieces.   The finished subassembly went back onto the shelf to await its installation on the right wing.

I also received a bearing that I had ruined and was planning on finishing the push rod that was affected, but doing so requires access to the front of a spar for measurement.   Steve & I put the R spar up in storage in a place that isn't convenient or safe for a single person to remove it, and the L spar now has nose ribs attached.  No big deal (except for my OCD).   It's a 5 min job and I can do it when I get access to the spar again.

Cool Picture

This is a pretty cool picture.  I just like the effect of staring down the perfectly aligned holes in the ribs after they are attached to their spar.  Check out December 5, 2013 for a similar shot of the RV-12 wing being built.

Empennage kit delivered

 Van's shipped my empennage kit (vertical & horizontal stabilizers, rudder & elevator) on the 5th.   It arrived in Columbus last Monday and I made an appointment for its delivery on Weds 12th.  When it showed up the driver spent about 10 min in the back of his panel truck, then came over to tell me he couldn't deliver it because it needed a fork lift and he didn't have one.   That's exactly what happened on May 9th when the first crates of the wing arrived!   That day, I enlisted my neighbor & his friend and the 4 of us manhandled the crates to the ground.  This time, I stood my ground and insisted that they re-deliver it.  Then I looked at the crate:

You'll notice something odd about this arrangement.  See the arrow?  Typically, that means "this side up", but the crate is on its side, not right side up.   

Yesterday, they arrived with a flat bed and attached parasite forklift. 

He got the crate off the truck and into my driveway and I pulled it into the garage. 

There was some minor damage to the wood and the paperwork is partially outside of the box.  I signed the e-receipt stating 'accepted with damage noted and not inspected'.  The driver/delivery guy was totally cool with that.  I'll file a claim with them if there are any damaged pieces when I get around to inventorying it next Thursday.

3rd time might be the charm ?

 Well, here's to hoping that I am capable of learning.  Specifically, this is the 3rd time I've sealed the fuel level senders & inboard access plate.   I have learned one thing -- I neither like nor am skilled with working with Proseal.  (BTW, Proseal is a brand name and I'm using generic products but will continue to abuse the name because I'm lazy.)

I'm pretty sure the access plates are not an issue because they are horizontal and straightforward.  The fuel senders are oriented vertically, so gravity is not my friend.  They also have a wrinkle in the installation:  one screw is fitted with an internal tooth washer, an electrical spade and a second internal tooth washer.  This stack-up is designed to have the angled teeth of the washers cut through the layer of sealant and ensure a good electrical connection from the tank itself to the electrical spade that will later be used to measure the fuel level.

On the previous installations, I had a lot of trouble holding the spade such that it didn't fall into the goop and I ended up making & breaking the connection of the sender's plate and the tank.  I suspect that didn't help the smooth, careful and uniform distribution of the sealant.

Rubber band as 3rd hand

I used a small rubber band to hold tension on the spade connector and trusted that the 'top' washer wouldn't go anywhere if I treated the arrangement with any delicacy.   In this photo, the connector is on backwards and would have dug into the side of the tank, but I installed it correctly after this dry run.

Sealant under electrical hardware

I smeared a small dab of sealant under the location of the hardware, then inserted everything and held it with the rubber band.

Smeared Sealant prior to installation

I then applied a bead around both the tank and the sender and smeared the beads into a relatively uniform bed.   Finally, I used one of my favorite tricks of inserting awls through two of the holes in the mounting plate and then into the corresponding holes in the tank and sliding the fuel gauge sender along the awls and into position.  I had a screwdriver at the ready to manipulate the screw (that was holding still because it was held by the rubber band) into its nut plate, then quickly inserted another screw into its nut plate. With two screws to hold orientation, the awls came out and the remaining screws were started, then evenly tightened.

Mounted Fuel Level Sender

As you can see in the final picture, there's a nice bead of sealant oozing out around the entire circumference.   It's a little thin at 12:30, but there is visible sealant. :)    BTW, I did both tanks at the same time, but only published pictures of one side.

I think the next time I'll have time to do a leak check is next Thursday, the 20th.   Fingers crossed!

§29-11 L, Nose Ribs to fuel tank

 Recall from a recent post that the Wiki community mentioned that getting the 6th rib attached requires two people because of the skins that are already attached to the tank making it impossible to hold the bucking bar and the rivet gun at the same time.  Steve B is a fellow RV builder and also an A&P.  In fact, he is the lender of the rivet gun I'm using to do this build.   He came over yesterday and used the gun while I assumed a very awkward position and held the W bucking bar.  Steve also noted that the FAA likes to see pictures of the builder and not just of the work done, so he offered to snap this:

Getting my head into the game!

Here's the photo of the rivets in question.  Even with the highlight, they're hard to see.  Imagine how hard it was to hold the bucking bar.   While I was in position, I had Steve hand me the go/no-go gauge and I discovered the top rivet needed a few more hits to meet spec and all the others were good.  I was really pleased! 

AN470AD4-12 shop heads

This completes page 29-11.

Busy & Productive Day!

Yesterday was a busy & productive day.  I got a descent amount of sleep after I got home at 8:30 AM.   In addition to the RV-15 stuff shown below, I also cleaned up the kitchen, trimmed all of the grass around the house where the lawn robot can't reach and installed the wall mount for a monitor in my wife's dance room.

• Got help & installed 6th nose rib
• resealed the tanks (again)
• received the empennage kit
• completed Right inboard aileron bracket

Rather than cramming all of that into one post, I'll make a separate post for each item.  Keep reading!

§29-06 thru -09 Left

Page 6 calls for making the spar even longer.  There is a doubler plate that connects a ~2 foot Spar Extension to the outboard edge.  I clecoed that up a few days ago and was very pleased with myself when 6 clecos went together nicely.  On Sunday I played Grandpa and gave Layne (an 8 year old) his 2nd lesson in riveting.  He did a good job of wearing ear & eye protective gear, too.   I shot my first 470AD4-6 rivet, but couldn't get the next one to insert.  Upon closer inspection I discovered that the doubler is not symmetric about the longitudinal axis and I had in fact installed it upside down.

Layne got another lesson; how to drill out a rivet.  It didn't take too long and I happened to have some spare 4-6's from the RV-12 kit so I won't be short at the end.

Wing Spar (gold) & Extension (silver)

I'm not able to re-seal the tanks (3rd time!) until I get some parts from Van's.  Specifically, I ordered replacement screws since the Phillips heads are getting stripped from so many insertion/removal cycles.  That left me with either the option of waiting around and wasting another day or starting another major component.   If there's a leak on the forward edge of the tank, I'm going to be very pissed at Past Me!

Attaching the main spar to the forward edge of the tank was very easy -- just my favorite LP4-3 blind rivets.   Attaching the inboard D-rib was pretty easy even with the ridiculously long 470AD4-12 rivets that were conveniently accessible from the root side of the wing. The next four D-ribs were another piece of cake as they, too, just attach with LP4-3's.    

On page 11, I came to a complete halt on the 6th rib.   To quote from the Wiki page: 6th rib from root: rivet gun + long-armed bucker through the lightning hole required. Plan for a helper or an unconventional body position.  That is an understatement.  I think even with a helper, it's going to be a bear.   I'm waiting for a confirmation that Steve B (he who lent me the rivet gun) will be able to swing by and give me a hand on Friday the 14th to finish that rib.   

The remaining 9 or so ribs will be attached with driven 470AD4-4's, which are not my favorite but will be easy to access.

inboard D-rib

§28-18 thru -21 Left Pushrod installation

 It's been a while since I last updated this.   Work is sucking up so much of my time, but that's how I keep up the cash flow to pay for this insane hobby.    Last week I finished up the pushrod installation on the Left wing.  It was fairly straightforward and kind of interesting to see how the system will work.  Basically, there is a pushrod extending from the root of the wing that will eventually connect to something inside the fuselage.  When that rod is moved outboard, it actuates a bell crank that moves the outer pushrod inboard.  This, in turn, pulls the small pushrod forward which will cause the aileron to deflect upward, thus banking the plane to the left.  It is left as an exercise for the reader to fill in the blanks regarding motion in the opposite directions.

Large pushrod at wing root.

Small pushrod at aileron attach point

Really getting a good look at the aileron pushrod system has done nothing to allay my concerns about how the flaps are going to be activated.  I identified a bracket that will hold a pulley for flap cables and can sort of visualize where something might fit in the inboard mixer box, but for the life of me I can't see how it's going to be retained in there since there are no nut plates or anything.   I'm guessing that there will be two cables in opposition connected to bell crank and one end of the bell crank will have yet another pushrod.  Why those components weren't included in the wing kit so they could be installed before buttoning up the skins is something that baffles me.   Regardless, I will trust the process and will complete the wing skins as directed by the instructions.

Finally, I have to report that the damn tanks are still leaking. It's a much slower leak now, and it's in the same place on both tanks -- at the ground lug that is behind the fuel sender plate.   I also learned that the soap bubble trick only works on really slow leaks and it did a great job of letting me see where the air was escaping.   On an academic note, there is a phenomenon known as Starling's Law that is really important in cardiology. Basically, the amount of stretch that you get out of a given pressure is highly dependent upon the radius (size) of the thing being stretched.   When you pump up the balloon with the hand pump, the balloon gets sort of inflated and does nothing for several pumps, then abruptly grows quite large without any further pumping.   Human hearts tend to do the same thing when they fail due to fighting high blood pressure for a long time.  It was really cool to see it in action rather than just imagining it as an academic factoid.

Today (well, yesterday) I spent two hours removing & cleaning the fuel sender units and the inboard access plates of both wings.  Man, I hate working with Proseal!   I'm going to use all new screws and lock washers for this 3rd attempt at sealing the tanks.   I've done some cruising through VAF and found several techniques that I will try to integrate into this next attempt.   Fingers crossed.

Finally, the tail kit is en route and should arrive some time this week.

§ 28 -6 thru 13 -- push rods

 Van's is famous for the smoothness of the control feel of their airplanes.  I think one of the contributing factors is that they use bearings and pushrods whenever possible when designing their flight control linkages.  I had already assembled the rotational bearings in bell cranks.  This post documents building the push rods that attach to them.

I also like a really nice technique they employed for establishing the exact length of the push rods.  When you build one, you can turn the stem of the spherical bearing to move the length in or out by 1/48" at a time.  When I built the RV-12, I remember trying to very precise about my measurement.  In the RV-15, they have you assemble the push rod and then use temporary bolts to insert into holes provided in the main spar.  In other words, the main spar has a jig built in to it.   Very easy to twist the bearings to get a perfect fit -- no tape measure required!

I used blue locktite as a safety feature for the jam nuts and ruined one of the spherical bearings when the locktite dripped on the bearing itself.  Although it felt like it was still moving freely in its race, I expect that it will not remain in good condition for very long.  I tossed it in the junk bucket and ordered another one ($26!) from Van's.

Aileron Push Rods

Push rods, prior to riveting and installation of bearings

I started the final assembly of this chapter where the bellcranks get installed in the mixer and the pushrods get attached to the bellcranks.   Even without the skins on the wing, it's definitely challenging!   I'd like to have a trained capuchin monkey w/ tiny hands to help out.    I am absolutely dreading / afraid of trying to install the flap control mechanism after the wing is closed up!

§27 L; IB Mixer - Rear Spar

 This was also a pretty straightforward chapter.  The Inboard Mixer was nestled into the space just next to the tank and directly in front of the spar attachment area.  The holes that were left open for the rear spar attachment were then used to rivet the mixer to the spar.  Here's where the infamous Cherry Max Rivets got used -- all 39 of them.  These are pull rivets ("pop rivets", although that's actually another brand name) but they are stronger than the typical LP3-4's used nearly everywhere else in the plane.   The book says to be sure to pull exactly in line with the stem, but that's not possible with a few of the rivets because there is a flange immediately in the way.  I bent the flanges as much as I could and did the best job possible.

IB Mixer, as viewed from the front of the wing assembly

For some reason, they decided to have the flap tracks installed in this chapter rather than give them their own chapter.   The flap tracks are interesting; they are jet black and I'm not sure if they're aluminum or something else.  I am getting better at riveting.  There were two rivets that couldn't be bucked with my titanium bar.  I used a flat plate of steel and got creative.  Worked great!

 

Flap Tracks

§26 L; Rear Spar - Tank

 I got a lot accomplished in the last week, but one thing I didn't have time to do was document it.  I typically have slow times between patients at night, but not recently.  Sorry for the delay.   I'll publish several updates in a row so i don't overwhelm you with a really long post.

Attaching the rear spar to the tank assembly wasn't too bad.  It was literally a one pager that consisted of bucking 33 rivets. The only challenging part was ensuring that I only riveted the holes called out in the KAI, as many holes were left open for the next chapter.

I'm starting to get a feel for when a bucked rivet will look good or look like a mess.  I think the key technique is to maintain pretty firm pressure with the rivet gun, but not much pressure on the bucking bar.  Time will tell.

Again, no picture as it really doesn't look any different.

flying instead of building

Well, didn't get out to the shop to do any building because I went flying instead.  I don't want to let my flying skills deteriorate due to spending all my free time building the new plane.  I was getting close to loosing my currency for IFR flights, so yesterday Ed & I took the Cirrus up for a good workout.

The weather was perfect for an IFR training flight.  There was a nice big low pressure system (29.69 inHg) sitting over Ohio yesterday and that gave us a cloud layer from about 1000' to 4000' above the ground.  I flew and Ed observed/coached/critiqued from the right seat.  I flew to Dayton, did a hold and shot the RNAV 24L approach there, all using the autopilot.  In other words, I programmed & observed while the plane flew itself.   That's the Standard Operating Procedure for an actual mission.   Then I disconnected the autopilot but left the flight director engaged and flew the same approach by hand.  The flight director essentially is a display driven by the autopilot that says, "if I still had control, this is what I would do."  Basically, it's a video game -- the A/P moves the cueing display and I fly the airplane to match the cue.  Then I turned off the flight director and flew using just the displayed location data.  I flew all the way back to Delaware by hand, went to the far side of the airport to get aligned with the wind and few the RNAV 28 approach back home.

Overall, 2 hours of a good workout and I feel better about being a competent pilot.

Back to building when I get home tomorrow.

§26 Left -- Rear Spar to Tank

Well, I took a deep breath yesterday and committed to joining the rear spar to the tank.  The section is a whopping 2 pages of actual instructions -- 1 page says to cleco everything together, the other says to rivet it.  All 33 rivets are 470AD4-4 that needed to be bucked since there was no way to get a squeezer anywhere near both sides.  

I am still quite leary of my skills in bucking rivets, hence the trepidation in this step.   Having said that, I'm actually quite pleased with how it turned out.   I am starting to get the feel of how much force to use with the bucking bar.  Counterintuitively, holding it with too much pressure simply causes a lot of noise and not much deformation of the rivet tail.  Obviously, not enough pressure and it simply bounces away.  If you use just the right amount of pressure, the tail of the rivet sets in only 8-10 impacts.

Some of the rivets were in a place that I could only see the shop head and had to hold the bucking bar blindly.   I'm quite surprised that it went well.  I did use the guage to ensure that the shop heads were within spec. 

Tomorrow, I'll finish riveting the spar, tank and inboard mixer box together.  Those use the famous Cherry rivets that are stronger than the regular LP3-4's but are harder to pull correctly.   The sealant should arrive tomorrow or Wednesday and I'll re-seal the Left tank.  They say 3rd time's the charm.  Stay tuned.

§28-14, -16 L&R Aileron bellcranks

 Two steps forward, one step back.    The right tank now holds pressure.  Sort of.   The left tank still has a definite leak at the fuel sender.  I used a cartridge of sealant from Aircraft Spruce, but the gun I bought (that morning) from Home Depot is much too large for the cartridge so I ended up just shoving the base with a spark plug socket as a make-shift plunger.  That made it barely possible to squeeze out the bead of sealant, with the resulting poor performance.   Since then, i've borrowed an appropriate sized gun and will give it another try when the next cartridge arrives from Aircraft Spruce.

I've been holding off attaching the spars to the tanks until they were sealed, but I'm going to go ahead and resume major construction since the leaks are at the other side and can be dealt with in parallel.

I built up the aileron bell cranks.  Took just a day and was a nice, straightforward project.

underexposed picture of the bellcranks

The aileron push rods have specific instructions to be primed.  I learned that just putting them on butcher paper and spraying them with primer, then leaving them overnight to get wet, results in paper that is well glued to the aluminum.  I sanded much of it off, but not all.   I stood the push rods using wooden dowels in the ground and sprayed them again while vertical.   I now have nice camo'ed push rods!

Aileron pushrods drying in the sun

 

§22-19 thru -26 Left

 Well, it's been a minute since I last posted anything here.  In addition to the usual 4-letter word ("work") that always is in the way, I had two very pleasant reasons to take a break from building.  

My eldest daughter came up from Louisiana with her family to visit for a few days.   Here are her 3 daughters and my middle daughter's son & daughter for a total of 5 grandkids.   It was a great, but short, visit.

One of the reasons it was a little short was that her visit overlapped with Thunder Over Michigan, an airshow held just west of Detroit.  My wife recently announced that she wanted to have a helicopter ride, preferably in a UH-1 "Huey", and of the attractions of the show was such a Huey.  Christie went to go stay w/ her sister and we drove up to Michigan and we got the ride she had hoped for!

Finally, back to building!  During the week, I received the extra parts from Van's that I had lost somewhere in the garage.  I finished building up the L outboard aileron attach bracket and got it riveted to the rear spar.  This completes the Left Rear Spar subassembly.   Recall that I had already built up the R outboard aileron attach bracket because of the mislabelled KAI. I thought I might as well build up the R inboard bracket since the workflow was already set up.  I then found the missing ouboard bracket cleverly imitating one of hte pieces needed for the inboard bracket.  This means that I'm missing that piece instead of the one that I just purchased from Van's.   "One step forward, one step back."   Sigh.

Next project:  Clean, scuff and re-seal the tanks.  I bought a larger batch (3 oz) of Fuel Tank Sealant than I typically use, but it's a 2 hr cure time instead of 0.5 hr, and it was actually cheaper than the 1 oz stuff from Van's.   I'll let you know how it worked in the next posting.

Left outboard aileron attach bracket assembly