Sunday, June 28, 2015

25-05 Rear Window prep

About a year ago, I tried to test fit the rear window into place, but it didn’t work.  I really should have pursued why it didn’t fit—I might have discovered the improper location of the roll bar much earlier in the game.  

Today, it went very well.  The material is very stiff & springy, so it was a bit of a challenge to work with, but not bad at all.  The photo was taken about half-way through the pages instructions, as the last two steps are to remove the plastic and do some drilling & tapping.  I thought this would look more impressive. :)


IMG 4466

Rear Window prepped in place

Friday, June 26, 2015

25-04 tail cone riveted to fuselage

Back to the fuselage / tail cone attachment process.  As you may recall, there was some problem getting things to align at the aft baggage bulkhead when Nick & I clecoed the tail cone to the fuselage.  To bring you up to date, here’s my posting to VAF:

Well, it looks like I got things taken care of. I ordered new roll bar bases in anticipation that I would need to remove/replace them to change the angle of the roll bar, but I will be able to return them to Van's. I removed the F-1254 support frames and drilled out the rivets securing the roll bar to the roll bar bases. Viola! The roll bar promptly cooperated with rotating forward and straightening out the F-1207 baggage bulkhead. I could not see any appreciable movement at the roll bar bases and could see daylight when I looked through the sides (left to right of the entire plane, not just each roll bar base.)

I fully clecoed the turtle deck skins to ensure that everything aligned properly. I placed two rivets on each base, and was unable to move the roll bar with some vigorous manipulation. Holes were still well aligned, so everything got riveted back together and I'm back on track.

Conclusion: My error when I situated the roll bar. It was a year ago, but I think I had to use a great deal of verbal lubricant (4 letter words) to get the bar to fully seat. That should have clued me that this was a critical junction and I should have been more careful about finishing the rest of the aft structures to ensure good fit elsewhere. As it was, I didn't notice that the baggage bulkhead was bowed toward the rear when I built that section last year. 


IMG 4457

new & improved fitting of aft baggage bulkhead and tail cone

Step 1 is deceptively simple.  Rivet the shear clips.  Well, the shear clips are now inside the back of the plane.  This was my first adventure climbing into the “the hole”.  While I was there, I routed the pitot tube through the loose tie wraps (2 years ago!) but discovered that the DB9 connector for the data cable won’t fit through the tie wraps.  I’ll replace them when I route the rest of the cables to the ADARHS. 

Step 3 is also deceptively simple, with only a few words more than “rivet...”  It took about 2 hours to remove each cleco, ream, rivet & move on until all were done.  Oh, well.  Lots of work, lots of smiles.

IMG 4456

Tail Cone installed on Fuselage

Sunday, June 21, 2015

12-08 Fairing Fit vs Rudder

The fairing was re-assembled and clamped to the tail after the Vert Stab & Rudder were re-assembled.  BTW, I didn’t use all of the bolts and washers to attach the Vert Stab & Rudder because I’m going to be removing them after I finish running the control cables (otherwise I can’t get the plane out of the garage!)  You can see a steel ruler taped in place to verify that there’s => 1/8” clearance from rudder to the fairing.  You can also see the rudder trim tab that is a $5 option from Van’s.  Because it’s a Van’s part and they have no objection to placing on the -12, I can do so prior to finishing Phase 1 flyoff (assuming that OK City ever gets around to issuing my registration so I can obtain an airworthiness certificate!)

Unfortunately, I ran out of time before I could put on the horizontal stab and finish up the fairing.  On the other hand, I’m not going to be working in the garage for another 5 days, and the H stab is going to completely block the use of the garage door.  Even if they’re not aware of it, I think my family appreciates my not blocking the door earlier than needed.

IMG 4451

Rudder vs Fairing

12-07 Fairing tabs

Little bit of sanding, little bit of drilling, little bit of riveting and now I have 8 tabs that will be used to join the upper and lower fairings.

IMG 4450

Fairing Tabs

Wednesday, June 17, 2015

12-06 Fairing Prep

The part that I don’t like about fiberglass work is cutting & sanding to the scribe line.  I don’t know what process Van’s uses for making the scribe lines on the pieces, but it surely one of the most subtle and difficult to see lines that I could imagine.

The Book tells me to cut a fairly simple top portion and a more complex lower portion out of a “C” shaped piece and a complete cone, respectively.  I did so.  Then I started the long & tedious (and moderately nerve wracking, in case of an excessive initial cut) process of mating the two resulting pieces to have a close fit along several edges.   I then had an idea that I think will work out well in the end.   Recall that one of the pieces was a complete cone.  that means that it contains all of the material of the “C” shaped   I took the top piece and put it on the discarded material from the lower cone stock and traced out the appropriate line.  

The 1st photo shows this stage.  Back Left is the lower part of the fairing.  Back Right is the discard from the top.  Front Right is the original top piece that doesn’t quite fit the lower.  Front Left is the discard piece from the bottom (originally, a full cone) with the top traced out.   I should mention that I don’t use shears to do my initial rough cuts prior to sanding.  I have always used a dremel tool with a narrow cutting wheel.   My insight was that I could trace out the top onto the discard portion from the bottom, then cut that out using the dremel.  The resulting new top would be a very close fit to the bottom, since they were originally a single piece.


IMG 4383

Fairing pieces


Photo 2 shows the scrap after both the bottom and the top have been cut away with the dremel tool. 

IMG 4385fiberglass scrap after cutting fairings


The 3rd photo shows the top & bottom fairings clamped into position on the tail.  There was minimal sanding needed of the adjoining surfaces.  The kerf of the dremel tool will be adequate for the gap specified by the book for paint thickness and the fit is a good as one could ask.


IMG 4384

Tail Fairing clamped onto tail

12-05 tail cone prep for fairing

Nearly 2 years ago I came up on this chapter and was disappointed, yet oddly relieved, that I couldn’t progress any further.  The kit has the fairings included in the Finish Kit shipment, yet the instructions are part of the empennage.  That was disappointing.  The relief was that I didn’t have to work with fiberglass, which at the time was a scary proposition.  Over the last many months, I’ve read and re-read the instructions without really understanding what they were telling me to do.  Finally, as is often the case, understanding comes with doing.  The whole thing about the tape is simply to get measurements onto the tail cone as to where I will later drill attachment holes.  Sigh.  The picture shows masking tape around the tail, decorated with clamps at the 12 locations that will later be drilled.  Wisely, I elected to not drill the holes now.  Reading ahead, I see that there will be some fine tuning and moving of the fairing to ensure clearance of all of the tail feathers.  Only when that’s accomplished do the holes get drilled.



IMG 4381

tail cone with measuring tape applied

Monday, June 15, 2015

deformation of Baggage Bulkhead

my letter to Van’s Support:

Hi folks,

Could you look this over and tell me if you can figure out what I did wrong?

Today, I attached (cleco only) the tail cone and noted that there appears to be deformation of F-1207A that prevents alignment with that part and the tail cone itself.  I didn’t notice it earlier in the build as it’s not evident until I try to mate up those parts.  

IMG 4377

The first photo shows the divergence of the tabs from the tailcone and 1207A as it reaches the midline of the structure.  It appears that the F-1232A Roll Bar Brace is pushing it too far aft.    The distance between the leading edges of the inner most tabs is about 7/16”.
The only anomaly that I have been able to identify so far that could cause this is the alignment  of the roll bar with respect to the longitudinal axis of the plane.  


IMG 4373

Photo 2 is from the right side of the plane.  It looks like there is a 1/16” gap at the forward edge of the roll bar.    Using the width of the roll bar as 1.5" and the height of the roll bar as 23”,  a little bit of trigonometry shows that there would be 0.95” of aft motion at the top of the roll bar due to that 1/16”.   Solving the other direction and using the measured displacement of 7/16” at the top of the fuselage works out to only needing the roll bar to be 1/32”  off of the surface.  In other words, the math seems to confirm that this is the culprit.
Since the front faces of the F-1231D Roll Bar Braces are pre-drilled, that 1/16-1/32” gap is not something I can control at installation.  I’ve  verified that the bases are tight against the airframe.
I’ve thought about removing and replace the 1231D Roll Bar Braces, but realized that since the front faces are pre-drilled, I wouldn’t be able to change anything on re-assembly.  The only other idea that I’ve come up with so far is to loosen the Roll Bar Braces and place one or two 1/64” shims on the rear edges.  That doesn’t sound like a good idea, so I’ll wait to hear from you instead.
Thanks for looking this over,

25-03 tail cone attached

Some very careful maneuvering and adjusting (using the variable height supports, not shown) and careful assistance from Nicholas resulted in a fairly un-eventful mating of the tail to the fuselage.  You can see the cradle that has been patiently holding the tail cone since it was built.  Sadly, it will have to be disassembled and scrapped, but it did its job well...

IMG 4371

25-02 tail cone prep for attachment

This is a close up of the tabs on the tail cone after they have been carefully (and ever so slightly) bent outward to facilitate mating to the fuselage section.  The shoulder harness attach points have also been prepped and are clecoed in place.  The yellow dust/pollen was vacuumed off shortly after this photo was taken.



IMG 4364

tail cone prepped for attachment

11-09 AST / Trim attach

The trim assembly attaches to the anti-servo tab (commonly referred to as the trim tab, which I will often do.)  The only thing I needed to verify here was that the gap between the push rod and the skin of the stabilator itself maintained a minimum of 1/4”.  It does.  Barely.  Exactly.


IMG 4359

Stick UP, trim DOWN —maximum clearance



IMG 4358

Stick DOWN, trim UP — minimum clearance

11-08 Trim Motor Assembly attach

The trim motor can now be mounted for operational testing.  Again, nothing was tightened to airworthy condition.  I put power to the trim motor for the first time and was very relieved to see that it worked as advertised.  On the other hand, I realized that I had wired one of the connectors backwards and the pins/sockets don’t line up all that well.  I can’t figure out how to remove the pins, even with the supplied tool, so I ordered a new connector and pins and wild just amputate the incorrect connector and install new.  That will also be the time where I make the final determination of which wire is +12v = UP and which is +12v = DOWN.


IMG 4355

11-03 Horizontal Stab attach

I rearranged the garage a few weeks ago to make room for the horizontal stab.  I know it will only be attached for a few days, but I wanted to ensure that it fit correctly before going any further.  I didn’t have anyone to help maneuver the piece, so I got creative.  I picked up some adjustable work support last year.  One on each side of the stab made a good working surface that could be elevated to the proper height as the back end of the tail cone.  The tail cone has been in a wooden cradle since last year and that cradle is on wheels, so I just inched the cradle back into position until I could get the AN4 bolts in place.  I didn’t tighten things down since this was just a temporary installation, but nonetheless, it looks good!

IMG 4351

Horizontal Stabilator in position

Thursday, June 11, 2015

37-08 Fuel Vent Line

I’m getting very close to attaching the tail cone, so now we’re taking care of final details that need to be done prior to attachment.  The fuel tank has been largely a non-issue since I purchased it as a complete unit rather than building it up from scratch.  (That’s because I was trying to avoid using fuel sealant as much as possible.  (I’m over that: If I do another RV-12, I’ll build my own tank.)

Why Van’s didn’t choose flexible line, I’ll never know.  I find bending tubing to be very challenging in execution despite being simple in theory.  The photo shows the two portions of the fuel tank vent line.    Looking through the hole for the filler port, you can see the proximal portion coming off the tank and penetrating the bulkhead.  Aft of that, you can see the distal portion diving down on its way to the ventral surface.  I didn’t actually connect the distal portion, as it has to penetrate the not-yet-connected tail cone.  I didn’t photograph a little tool I made to emulate the penetration hole which helped me with alignment.  I simply used the template that directed me where to drill the exit hole and mocked up a 3x3” piece of aluminum from scrap, and attached that to the fuselage.  That gave me a mechanical / visual reference to use when I bent up the tubing.  After the tail cone is attached, it should be a simple matter to put the vent line into an Adell clamp and make the final insertion into the T-fitting, then just connect the anti-siphon air line to the ventral static point rivet (already installed.)


IMG 4343

Fuel Tank Vent Line

SB 14-12-06 Replace F-1206F Bracket Bearing Brace

Van’s issued a service bulletin regarding cracking of the F-1206F bracket bearing brace.  The SB calls out for annual inspections for any cracks, and if any found, remove & replace the brace.  Rather than risking a difficult job when the plane is done, I elected to remove/replace before installing the tail cone.  At the bottom/right&left of the horizontal metal rate, you can see thick aluminum (cut from an angle extrusion) which constitute the improved part.


IMG 4348

upgraded F-1206B bearing bracket brace

Thursday, June 4, 2015

40-10 Nav/Stobe attach

Here’s one that I was afraid of screwing up, and I did.  The Book calls for using fuel tank sealant (visible as the dark grey under the edge of the fiberglass).  I got everything all set and finally mixed up the goop and went to work.  After I had pulled about half of the rivets on the Left wing, I noted that I had neglected to pull the wing’s wiring harness through the opening of the fiberglass and it was now firmly buried inside the wingtip.  I said a few choice words (loudly, apparently, as Nikolai was able to hear me and showed up with concern for my well being).

I elected to keep working while the goop was still usable and proceeded to finish on the R then L (after pulling the cable through the fiberglass).  Many, many, many years ago my high school teacher told me a story wherein he did an electrical job in exchange for a “fish”, a stiff metal filament used to pull wires through walls.  I bought one when I had my first house in California (1988) and I wanted to pull ethernet wires. Never used it again until today when I pulled the connector close enough to get it with a pair of forceps and was able to deliver it through the opening.  Whew!


IMG 4341

Landing Light & Nav Light

40-09 wingtip wiring

The wiring for the wingtip has been hanging out inside the wing for a year.  Now it was time to terminate it (and the wires on the Nav/Strobes, too.)   I noticed that one of the wires on the R wing was a bit longer than its partners, but I just cut it to length and went on.  Remember Van’s Dictum?  If something doesn’t look right, it’s not.

I did invest several hours cobbling together a test cable that had just 8 straight passthrough conductors for the wing connectors.  I used that to electrically connect each wing to the plane and verify that everything worked.  Well, it did on the Left but no strobe on the Right.   Basic trouble shooting eventually led me to the wing root connector being at fault because there was no wire in pin #8. I reached in the wing and found it about 10” outboard.  That’s when the extra 10” I trimmed suddenly made sense.  Damn.  About an hour of doing other things while my hind-brain chewed on the problem led me to the easiest solution of splicing the length back on the outboard end and pulling the wire medially again.  Luckily I had many spare pins available to re-terminate the wire and we were back in business.


IMG 4338

Nav/Strobe wiring harness

40-08 wingtip light prep

By the way, I forgot to mention last posting that it was very convenient working on the wings while they just sat in their cradle.  I had been mentally preparing to re-organize the garage and temporarily put the wings on a table.  When I looked at things, it turned out that they were ideally situated to work on.  Nice!    The same good luck held for the wing tip lighting project.

Now, this is a project that I’ve been dreading for over a year.  I was simply not able to face dealing with the fiberglass and epoxy stuff involved.  I had read the instructions multiple times, but it never made any sense to me.  Now, after doing the cowling, it’s much less confusing.  Onward!


IMG 4336

prepped fiberglass wing tips


The fiberglass was trimmed to the appropriate line, holes were drilled, access ports were opened, and wax generously applied to the wing tips.  Epoxy got mixed up and sloshed inside the fiberglass edges then the whole thing was clecoed to the wing tip.  I didn’t quite get a complete fill on one edge and will probably do a re-work by mixing up more epoxy/flox and injecting it into the gap, but it’s definitely usable in it’s current state.  (The rework will probably happen when I tackle the very last project—wet layup of the canopy fairing.)

SB 14-11-03 Wing Skin / Spar Flange rivet wear

This service bulletin came out last fall and calls for annual inspection of the rivets at the bottom wing skin and to add this doubler if any signs of wear.  I elected to just install the doubler and not wait.  Note that the SB still calls out annual inspection for wear, but this makes it extremely unlikely to find such.  There are no less than 4 separate rivet types in this doubler.  The zig-zag row on top and the lateral portion of the middle row are ordinary LP4-3’s.  The next 8 in the middle row are 5/32”, and the inner most rivet (still on the middle row) is a Cherry Max.  The bottom row of zig-zag are very low profile (inner surface) since there is very little clearance below them.  All in all, it was a nice day of good old fashioned metal work.


IMG 4330

wing root doubler