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

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; OB Mixer-Rear Spar

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.

Setback -- The Fuel Tanks Leak. A lot.

Well, I finally had an opportunity to work on the fuel tanks again.  I lost a day or so because I never read the manual on the little bicycle tire pump and I was putting it on incorrectly.  I thought it was defective and went to the aviation division of Walmart to find a pump with a different kind of connector.  There weren't any.  There was, however, one brand that thoughtfully provided an instruction card and I learned I had been trying to attach the pump while it was in the locked position.  Duh.

I got home, correctly attached the pump and tried to pressurize the left tank.  The balloon barely quivered with each stroke.   Damn.

Armed with my granddaughter's bubble soap, I put the tank on stands out on the driveway and liberally soaped up all of the seams, the access panels, the fuel sender, the supply lines, vent lines and balloon neck.   Nada.  I can't generate any bubbles at all.   I'm pretty bummed.   I washed off the soap and put the tank back on a solid table.   I rigged up the right tank and got equally nowhere, but I didn't bother to soap it up.

I've learned not to do anything when I get into a spot like this.  By doing nothing, I can't make it worse.  The fact that both tanks are completely incapable of holding any pressure at all implies that I'm missing something fundamental that will probably be obvious in retrospect once I find out what it is.

Tonight, I'm going to think about options.  I'll write to Van's and ask how they pressure tested the tanks without them being sealed and see if that sparks any intuition.  I'll look into acquiring a 4' x 6' x 1' plastic tub and might try to immerse the tanks under water and look for bubbles that way. (That's going to be 240 lb of buoyant force to deal with, so I'll need some brawn to help!)   I'll check w/ some RV builders at DLZ and invite them to come help me troubleshoot.   Something.

Tomorrow is a day off and I don't want to throw it away by doing nothing at all, so I'll start on the next section of constructing the aft spar and ribs.  As long as I don't attach anything to the tanks, I am maintaining their current state and not impairing my ability to troubleshoot later.

§21-11R, -13. Sealed access plates R tank, installed fuel drains

As expected, it wasn't difficult to apply B2 sealant to the access plates on the top of the right tank.  Overall, it took about an hour and about 3/4's of the jar of sealant.

As expected, it was much more difficult than it should have been to install the fuel drains.   The instructions on page 13 are deceptively simple -- Install (1) into (2), where (1) and (2) refer to the fuel drain and fuel tank, respectively.  It doesn't mention using anything to create a seal, but I know that those types of threads (NPT) aren't actually fluid tight and must have a sealant of some sort.   Basically, it boiled down to using B2, as is used everywhere else, or Loctite 565 which is called out in a different chapter but never mentioned in the actual instructions.  I posted a query on VAF and was told RTFM (section 5) where it generically calls out Loctite 565, so that's what I went with.

As mentioned a few posts ago, I had tried a simple trial fit by installing (finger tight only) those components, and somehow managed to strip threads.  I wasn't really sure if they were stripped inside the tank (horrible) or just on the $30 part (not too bad).   

I researched the drain and found that it was a 1/8" NPT.  I couldn't find any technical description of the threads for the part from Van's.  It appears that all 1/8" NPTs are 27 pitch but that was only because that was the only pitch number I ever encountered and it was rare to find it at all.  I bought a set of cheap taps & dies at Harbor Freight that included the desired NPT.  I've tapped internal threads before, but never cut or chased external threads.

Some scrap Al from the RV12 was used to make a test hole with the tap and I was able to thread the fuel drains into that.  This confirmed that they were indeed 1/8 NPT 27.  I debated chasing the external threads on the drains, but wasn't sure which side of the die was the starting side.  Since NPTs are tapered, doing it backwards would probably destroy the part, so I deferred.  In retrospect, I think running the drains through the test hole actually chased them a little anyway.

The tap was used to very gently chase the tank.  I only used finger pressure and no tools.  The drains got gooped up with 565 and I tried to install them.   Nope, the threads wouldn't engage.  I finally got them to engage and tighten by pushing up on the drain with my thumb to and apply a fair amount of axial load while gingerly rotating them with a closed 1/2" wrench.  Finally, success.  It only took an hour to install two bolts.

Right Fuel Drain

§21-07 thru -10, -11 L, -12. Installation of fuel senders, access ports, fuel caps

Two days ago I got a lot done and pretty much finished sealing up the Left tank.  I ran out of time, energy and sweat and didn't seal the access plates on the Right tank, but that is now one of those "just get 'er done" things since I've gone through the process and know what / how to do. 

To explain; we left off with both tanks inspected and rinsed w/ 100LL avgas.  There was no debris and we found nothing in the rinse process.  The tanks had a few days to dry before I got to work on Monday.  The plans call for bending the float attach arms for the two fuel senders and give some engineering drawings to show how to do it.  I did both of them backwards.  Luckily, it turns out that that configuration is perfectly acceptable.  The only variation is that the float arms are 'pointing' in the direction opposite of the drawing, but this is on an axis that is parallel to the actual pivoting, so it makes no difference.  (sin 0° = sin 180°).

The R fuel float was very stiff and would actually stay in whatever position I put it. This is not going to give an accurate fuel level measurement since the goal is for the float to fall by gravity and float by buoyancy in the fuel.   I actually didn't realize this until after I had applied the pro seal (or "B2", as Van's now calls it) and was in the middle of trying not to make a thorough mess.  I was able to gently apply a little bend in the mechanism such that it no longer was binding and free falls properly.

Right Fuel Sender, Internal View

I got both fuel senders sealed in place with the left over B2 sealant from the second flap.   It definitely was harder to work with and was getting stringy towards the end, so I'm pretty sure that it only had a few minutes of shelf life with which to work, but it was still spreadable enough that I'm comfortable that I have good seals on the fuel senders.   We'll find out soon.

Right Fuel Sender, External View

The inspection ports on the Left tank weren't too bad, but I was surprised that I used up most of a jar of B2.  I have one left in the freezer to do the Right tank later today.

As mentioned last time, I stripped the threads from the L fuel drain.  I have the 1/8' NPT tap from Harbor Freight and will address that later today, too.  With that done, the R tank will be curing for 24-48 hours and I'll start pressure testing the Left.

Stay tuned. 

§21-06 Fuel Tank Inspection & Wash

Well, I got all prepped and studied up for doing section 20.  I got the tanks out of their containers & unwrapped them and was pleasantly surprised that section 20 was completed by the factory.  One more down w/o any effort!

Section 21 is all about prepping the tanks and sealing them up.  I inspected the insides with a video scope and found them to be spotless.  There were no 'hanging chads' of sealant, any debris to be found, and all of the specified internal passages were open. 

The book says to fill each tank with 3 or so gal of 100LL and throughly rinse the insides, including turning the tanks upside down.  I looked at the 4 big open inspection plates and decided that it would be a good idea to put the plates on, otherwise we (Lada & I) were going to just pour all that avgas all over the garage.  There are two fuel pickups (6D) and two vent lines (4D), but the kit only included 1 each of the end caps, so fuel did make a bit of a mess.  Lada took the brunt of  the spill but didn't complain because she has a curious appreciation for the smell of oil & gas and stuff.

I did try to stem the mess by hand threading the fuel vent lines into their ports.  The L tank was straightforward, but the right side wouldn't thread.  I gently applied some torque w/ a wrench and promptly sheared the first couple of threads inside the coupling in the bottom of the tank.   I did some research and verified that it's a 1/8" NPT which is readily available at Harbor Freight.  I'll pick up a tap in a couple of days and will very gently chase the threads and try again.

Left Flap completed, §36-24 thru -26

Well, yesterday I said that I had estimated it would take 3 hr to complete the Left Flap.  I must be getting better at this (or at least lucky) since it took 2:50 to finish the job.   Lada helped during the pro seal application and fitting the trailing edge.  It's much easier with 4 hands instead of just 2.  I propped the skin up with some rags under the skin and against some ribs.  I only used about 1/2 of the jar of proseal and made essentially no mess.  Then both of us flexed the trailing edge around the back and it was done.  I spent the rest of the afternoon pulling the rivets, putting the ailerons & flaps into moving blankets and then cleaning the garage.  All in all, a very satisfying afternoon.

 completed Left Flap

both ailerons & both flaps

All wrapped up!

about 1500 pop-rivet mandrels

Right Flap completed §36-25, 26

I got off to a late start today because I worked a night shift last night and then had a 4 hour morning course to renew that pesky ATLS certificate.   I slept until 5:00pm before heading out to the shop.

I left off yesterday with the right flap fully skinned but not yet riveted, so all I had to do this afternoon was  pull rivets and finish the FL-15500-002 Right Flap. 

FL-15500-002

Close up of the vortex generators on the upper surface

Once that was done, I got to work on the left side.  The lower/training skin was peeled & deburred.   I hadn't deburred the vortex generators on the leading/lower skin so that got done, too.   I've fully clecoed the leading edges of the skins, but will stop here.  Tomorrow, I will rivet the leading edge & generators together.  That will provide excellent alignment for the one-and-done fitting of the trailing edge once the B2 sealer is placed on the rear lip.   It should take about 3 hours (so I'll budget 6) to finish before I go back to work tomorrow night.

§36-05 through -20 (Left), §36-21 thru -23 (both)

 It's been a very productive couple of days.   I built up the substructure of the Left flap, installed it into the forward/lower skin and verified that the upper/rear skin fit on both flaps.  I fully riveted the forward/lower skins on both of them.  

close up of typical cleco and rivets prior to pulling

overview of same state of construction

Dale came over and helped me bend the upper/rear skins.  The general portion of the KAI recommends using two boards that are hinged together to make a tool to bend the sheet metal into the final shape.   It didn't work worth a damn.  Bending the trailing edge all of the way to touch the other side did nothing; it simply sprang back to its original shape.   Following the advice of a VAF post, I ended up putting the flap skin on the floor, laying the board over it and literally walking on it back and forth and even springing up & down for good measure.   This produced about 75 % of the desired decrease in radius of curvature.   It was enough that it was not difficult to cleco together,  In fact, it was much easier than the leading edges of the ailerons, so I suspect that I'm in the correct ballpark.  I will enlist the opinions of other RV builders regarding the final shape of the trailing edges.

Last night I tackled the dreaded fuel sealant step and actually didn't make too much of a mess.  I had already riveted the forward/lower skin.  I scuffed the area that would get the fuel sealant.  I slide the upper/rear skin under the forward skin and fully clecoed it in place.  The natural spring in the sheet metal kept the rear edge away from the lip that got the sealant.   I smeared the sealant in place in about 12 minutes (out of a 30 min working time) and had a pretty easy time of clecoing the upper skin down onto the sealant.  I flipped it over, and clecoed/riveted the underside.  I was about half way through finishing all of the riveting (boring, but very satisfying) before having to close shop and go to work.

I'm expecting that I'll finish up both of them with another solid day in the shop.

RV-12 myth busted

 A few months ago I read a comment that you could tell your non-flying partner that in the event of pilot incapacitation, they could close the throttle and trim the plane full-up in order to achieve a controllable, low speed (and hopefully survivable) forced landing.

I had my doubts since the RV-12 has a very powerful stabilator and I can't recall ever getting close to full-up or full-down.  I took her up and tried it out.  Yep, it's not a good idea to put in full up trim. Even without power (prop wash over the stabilator), the plane was nearly in a trim stall with only 75 % trim.  I didn't push it any further and went home to continue building.

§ 34-14. Ailerons complete

Right now, it's about 3:00 on Saturday the 20th.  I'm pretty busy working on the plane and haven't bothered to update this for a while, so there's going to be a series of posts that cover the last few days. 

I finally finished the ailerons!   The replacement AN509-8R16s arrived.  I still can't remember what the new MS designation is, but the last two digits in that code do not match the AN suffixes.  In other words, I had several collections of the wrong size sitting around before the correct ones arrived.  I primed the lead because I have no idea how well the priming covered the inside of the steel tubes.  I realized that there was actually a fair amount of binding on the steel tube rather than the lead.  I used a #19 drill bit and re-drilled the factory holes and used a lot of 'English' (precessing the drill bit while drilling through the hole) and viola! -- the AN509's slipped in easily.  The left side went together w/o problem.  The right side was noticeably loose since I had chased the lock nuts so I used blue lactite to securely hold them in place.

The photo shows the completed ailerons.  In the foreground is the Right one and its uninstalled lead weights.  In the background is the completed Left one.  Note the fact that it is clearly nose heavy and has tilted forward since the center of mass is now in front of the center of rotation.

§36-05 thru -20 (R)

It's been a busy two days.  First, let's get the bad news out of the way.  (It has nothing to do with the plane, so, relax.) In order to be legally allowed to do my job I have to hold a set of "merit badges" such as BLS (CPR), ACLS, PALS, NRP and ATLS.  That last one, Advanced Trauma Life Support, is good for 4 years.  My current certificate expired on the 11th and I was informed that day that I was not allowed to work until I get it renewed.  I had received a warning, that I would be "locked out" of the schedule but I took that to mean that I could not be scheduled for any additional shifts.   I was never told that I had to stop working.   This has thrown a major monkey wrench into the ER's of two of my hospitals.  They are scrambling to find people to cover  4 shifts of 24 hrs each.  I've done what I can and will trade one shift to work at a hospital where I'm allowed a grace period to renew my ATLS.  Interestingly, I'm being told that the mandate is system wide, yet I'm allowed to work at Grady.  Go fig.   I renew on Saturday the 20th.

The good news is that I suddenly have an entire week off and I'm going to make good use of it!

As the title says, I got 16 pages done on the Right wing.  We're making progress.   Marking a page off in the book doesn't convey the prep work that goes into just assembling parts.   Most of yesterday morning & afternoon was spent clecoing all of the flap ribs onto the spars.  It went great, with only a few expected moments of head scratching ensuring that I was on track for L vs R.  Again, I would greatly appreciate Van's making explicit direction marks on their instructions and maybe a few comments to help orientation.  For example, on the flap spars a comment such as "The inboard side of the spar has two lightening holes between the 1st and 2nd rib.  The top webbing faces forward."     Anyway, after a false start or two I got both sets of ribs fully assembled. 

Ribs attached to the wrong spars

I looked at it and get ready to rivet.  Then I paused.  Then I pulled out the skins and laid them on the table and inserted the L rib subassembly into the L leading edge skin.  Everything slid together perfectly.  Happiness.  Just because I'm anal-retentive, I decided to cleco everything together so it would have some structural rigidity.  The ribs fit right in.  

Then I realized that the the holes in spar did not align with those of the skin.  I spent about an hour trying to figure out what had happened.  I never figured out how I spun myself into that circle of mistaken L vs R parts, but eventually I got both spars into both skins and then reattached everything.   The left flap (assembled w/ clecos) went onto the shelf and I went to work on the right.

Left flap assembly, correctly oriented

Last night I finished up deburring and fluting all of the ribs and hardware attach points.  Today, I tackled bucking the larger rivets that are what hold this plane together.  All in all, I think I did a pretty good job, but I'm nowhere near being consistent.  Oddly, I think that I may be holding the bucking bar too tightly.   The physics isn't completely clear to me but it might be that if I hold too tight then a lot of the impulse goes into moving my fingers against muscle force and that dissipates energy into my hand.  Maybe by letting the bar absorb all of the impulse, more energy is reflected back into the rivet to cause it to set.   I'll think about it later.

Typical driven rivets.  Factory head (on top) has a "smiley" 

which is only a cosmetic defect.

The 3 shop heads are acceptable. 

At least 80-90 % of them look pretty close to the text book pictures.  A few are ugly but serviceable.  One is clearly a basket case, but drilling it out will cause more damage to the flange and actually weaken the final joint so it stay.  In case you're curious, it stays hidden because this all internal stuff that will never be seen again after I close it up.

I'm taking a lunch break and plan to write more later tonight.

Intermission

I'm have a lot of trouble finishing the ailerons.  The last step is deceptively simple -- insert the lead weights and install screws to hold them in place.  Unfortunately, there is no way to apply back pressure to the nut plates in which the screws thread, and without back pressure it is very difficult to get the threads to engage.  I've ruined the AN509-8R16 screws that came with the kit. I ordered new ones from Aircraft Spruce, but they use the new designation and I ordered the wrong sizes.  (yes, sizes--plural.  I want some screws that are a tad larger than called out to try a few tricks.).  I'll document the issue in more detail when I get it finished.

As is typical for me, when I have a problem or am facing a "don't screw this up!" task, I often take a break and do something else for a while.  I find that it lets me ruminate on the problem and reduces the risk of doing something out of frustration and making it worse.  This weekend is one such example, hence the title of today's posting.

Remember back in June 2013 when I built a toolbox as a practice kit?  (No, you don't.   But you can go read Metal has been bent; Rivets have been placed for reference.)  That tool box and a second one have been accumulating miscellaneous small tools for 13 years.  Van's isn't selling that practice kit any more, but I got a different practice kit that's a lot more fun.

Light Box

Light Box in the dark

This is a very simple, straight forward aluminum box with Van's logo cut out from the front.  It's internally illuminated by a strip of LEDs.  The point of the kit is to learn how to work with aluminum sheet metal and rivets.   As mentioned in the 2013 post, I really didn't want to use driven rivets.  To be honest, I have been slightly afraid of driving rivets all this time.  I have a borrowed a rivet gun from a hangar neighbor and bought some accessories including a totally cool tungsten bucking bar.  (It's really fun to feel its heft as it's about 20 % denser than steel!)  I finally bucked rivets to build the box and it really wasn't a big deal after all.  I feel much better about the fact that I will be driving rivets to assemble the main wing spars in a month or so.

I also painted it. (duh!) I made it another learning opportunity by using two different brands of primer before painting.  I have a clear preference for one of them, so I'm glad I did it.

The second part of the intermission involves the tool boxes mentioned above.   When I started building this month, I just had a bunch of tools moved from the hangar and thrown into a new tool chest.  They really weren't organized and just kind of thrown in at random.  I quickly ran out of space and yesterday I bought a second tool chest.   

Before:

two tables full of loose tools

After:

Two organized tool chests

Now that the light box is finished and the tools are properly organized, I'm going back to building.  I'll start on the flaps while I wait for the AN509-8R16's to arrive so I can finish the ailerons (eventually.)