You guessed it, more nutplates - 5 hours

Today I finally managed to finish off installing all the nutplates. Just a few one legged nutplates left to do on the luggage ribs and the crotch bracket. Setting went well, but getting the nutplates on the aft crotch bracket was interesting. I tried to squeeze the rivets, but soon figured out that it wasn’t going to work. I ended up setting them with the back rivet set and the squeezer.

Next I was ready to assemble the crotch strap brackets to the seat ribs. I bucked these rivets with the gun and bar. Slight change-up, I put shop heads to the outside. Turned out excellent!


Next item on the to do list was to dimple the F-704 Bulkhead/Spar. I dimpled the aft spar flange and then cleaned and primed it (as it will mat to the bottom skin).



 Next I needed to address the forward spar flange. I carefully figured out which holes do not get dimpled and taped those off. Checked, checked and rechecked. Then dimpled the remaining holes.



Now the last nasty step. Since I am building the 7A, I need to counter the top of the first five holes on each side of the flange to allow for a double flush rivet. Good luck getting a countersink cage in these holes, so I tried doing them by hand. It took a while but I managed to get all holes (5 per side).



Next I primed the bottom of the flange.

More nut plates - 2 hours

Been quite a busy week and I've had no time to work on the project. I did manage to drag myself out into the garage to finish up some of the nut plates on the baggage ribs. I needed to prime 4 countersunk one leg nut plates so I can install them on the end of the 4 baggage ribs. SO I managed to clean and prime those. Just need to let them dry.


I will also need to change out the yoke on the squeezer once I am done with riveting to then get at the nut plates on the crotch strap brackets that are really tight to get to.

Priming nutplates and riveting nutplates - 8 hours

I started early in the morning cleaning nut plates to prep them for priming. And yes as everyone says....there is a lot of nut plates.




Once the primer had a few hours in the sun to dry up a bit, I started riveting them to the seat ribs.

Riveting went fairly well. I few I needed to drill out and try again. But all in all, it went faster than I had anticipated.

I just have a small of nut plates finish off. The crotch strap brackets and a few baggage ribs needs some attention still.

More priming center section parts - 4 hours

Managed to pick up some more primer. I can finish off priming the baggage ribs.
 
 I also picked up some a small can of automotive paint to try a sample interior color. (Dark gray metallic). Using the scrap F-747L baggage floor, I primed both top and bottom of the floor. Top was primed with regular self etching primer from the spray can. The bottom was primed with 2 part epoxy primer. Top coat both sides is the Automotive Paint spray can. It will be a good test to see how well things will stand up for painting the interior. 

Priming Center Section Parts - 4 hours

Not much to report. Started priming the F-716 seat ribs.Again my priming process is very tedious

Wash with soapy water and maroon scotchbrite/rinse/acid bath/rinse/MEK/Prime.
 
Unfortunately I ran out of primer before I could prime the baggage ribs.

Making doublers and templates for the center section - 7 hours

I will need to make a spacer for the aileron trim at some point. Since I don't have 0.063" material I decided to make a template out of scrap. Once I can get some thicker material in I can make the spacer. It takes only a few minutes to make it.



Next, I had cut some strips out of 0.025" scrap to make a doubler for the F-716 seat ribs as per vans suggestion (See the July 7,19 blog for details). Fortunately I have a good bit of 0.025" scrap so I went to work on the strips. I had decided to make full strip doublers for a number of reasons. Not all of the AN3 bolt holes are in the best location so I fell more comfortable making doublers for all the flanges. I don't think it will add a bunch of weight, but it will add safety. Next, a full size doubler will be fairly quick and easy to make.

Lots of time spent making, cutting on the bandsaw, sanding, then edge deburring.

Minimum edge distances are marked on the strips and then numbered to match the ribs. Here is pics of all of them so there is a good record of whats there. The doublers are going to cover up the flanges.
 



The holes for the AN3 bolts were drilled.

I then marked the overhang on the both the top and bottom of the doublers. Trimmed then and rounded the corners on the 3M wheel.
Next I notched the holes for future wiring.

More dimpling, more edge prep on center section - 8 hours

So one of the items that is weighing heavy on my mind is how to attach the baggage floors to the F-706 bulkhead. With a little bit of research the baggage floors will need to attach with #8 screws, however they will need to be flush mounted to allow the F-751 baggage bulkhead to sit properly.

Countersinking the bulkhead for the #8 screws concerns me. I just had the one baggage floor crack on me, which is easily replaced however if I have the same issue on the F-706 bulkhead after its installed it will be devastating to me. To make matters worse, one hole on the bulkhead is through 2-layers. I really wish I had done this back during the F-706 bulkhead assembly.

I was determined to solve this sooner than later. So first step I removed the primer from the holes in question on the bulkhead. This will allow me to lube then dies when dimpling. Next I opened the factory holes to #19 using a MDF backing block and stepping up drill bit sizes. I then carefully polished the holes with #600 grit paper on the dremel mandrel and buffed the holes with 3M maroon scotchbrite.

I then lubed the dies and material, took a deep breath and started to dimple. Thankfully all dimples turned out perfect, including the ones through the double layer of the bulkhead.


Feeling good from dimpling the #8 screws, I dimpled the #40 holes on the seat and baggage ribs.

Next was the very long and tedious process of deburring the corners, nooks and crannies. Went through a lot of 3M maroon scotchbrite squares on the dremmel but the job is done and done well.

Edge Prep of Centre Section Parts - 2.5 hours

Fairly boring evening in the garage tonight. I prep'd and deburred the edges of the center section pieces. Tomorrow I will need to deburr all the corners, nooks and crannies.

Primed the F-776 Bottom Skin - 2 hours

I dimpled the most forward edge of the F-776 bottom skin that was left outstanding from yesterday. (Minus the countersunk holes).

Next I prepped and primed the F-776 skin. (Washed, Cleaned, Wiped, Acid washed, cleaned and primed)

Aileron Trim Motor and More center section dimpling - 10 hours

I just got back from holidays, so I am eager to get back to the build. Fortunately I don't have to be back to work until tomorrow so I have a full day to myself. I spent the morning unpacking and cleaning, then the rest of the day was a huge build day.

I set up the aileron trim motor and installed the linkages.

I then connected the wiring to allow my to operate the trim motor as per the instructions and found/marked the centre position. I soon found out how poor my wire strippers are on aircraft tefzel wiring, so after some reading I soon found out that I will need to buy some proper (expensive) wire strippers. I will have to wait for payday to order those and I after this, I wont be doing any wiring for some time. So I'll suffer with the poor wire stripper for now.


I then set up the assembly to find the centre alignment line. This I took my time on and went back and forth a bit, but I managed to settle on an alignment. I clamped the assembly and drilled the mounting holes.




I have a lot of questions on how that trim motor should sit on the bead in the rib. The instructions say to allow the motor to distort the bead. Which raises more questions then it answers. How much distortion is ok? A bead in the rib is used to increase the rigidness of the rib, so distorting it will reduce that. If I flatten a portion of the bead, is that ok? If i build spacers, will the trim motor interfere with the aileron pushrod? Unfortunately when googling it, there is not a whole lot off build logs that delve into this area. I posted a question on the Van's Facebook group and after a bunch of responses I sort of wished I didn't.

Let's just say, in the end, I think for my build I will make a spacer to allow me to mount the trim motor and not affect the bead. When measuring the depth of the bead, it only is 1/16" so the spacer I make can be from 0.063" material. (I'd prefer to make a proper spacer, rather than use washers). I'll put this on my future order list and make this space at a later time.

Next I dimpled the baggage floors.

Unfortunately on the left baggage floor I forgot to prep the factory/pre-drilled #19 holes on the one side and when I dimpled them, the holes cracked. (If you dive back into when I did the fuel tanks, I figured out how to dimple #8 screws without cracks - garetsrv.blogspot.com/2016/03/)  So I need to replace the left Baggage floor.

I moved on to the F-776 bottom skin. Quite a lot of hole and edge de-burring. But I finished the evening by dimpling the #40 holes on the DRDT. I will dimple the most forward holes (F-704 forward spar) with the pneumatic squeezer. I also choose not to dimple the holes for the F-623 corner ribs as I still have to cleco those pieces for fitting and drilling the side skins. At the end of the night, here's what it all looked like.

A few new parts arrive

A received a few new parts in the mail that I ordered prior to going on holidays. From Cleveland - A new #8 dimple die (I had to grind down the edge of the one I have for the baggage ribs) and rudder cable fairings. From Vans - New flap mounting blocks and some seat belt attach hardware. I have to remove the seat belt brackets to rivet the center section and I do not want to reuse the old hardware.