Even more armrest work - 2 hours

Now that I have the armrest angles all marked out, I began the tedious process of drilling and opening up the lightening holes. I started at #40 holes, then systematically opened them to 1/4". The weight now drops to 163 grams so too bad from the original being over 200 grams.  

More arm rest work - 2 hours

I managed a little bit of time tonight on the build. I started off by countersinking the angles to allow for the dimples in the armrest. Also, I need to start thinking about holes for reducing weight. I dug out the fan spacer and decided I would mark centre between each rivet hole to allow for removing material.

 

A laundry list of items

 I've basically finished the items noted in the instructions up to the point where it says "Riveting the forward side skins". The instructions note that " There is a laundry list of small task that must be completed. You may have done some already. If not, complete them now" The instructions are rather vague on what these might be. But I've already started a to-do list some time ago on all the things I need to still finish off.

Here is my laundry list of items (in no particular order):

 With everything still cleco'd together

• Finish match drilling the fuse (center section/aft section. seat ribs, etc, etc)
• Open up the #30 holes to 3/16" for the front wing attach bracket.
• Drill landing gear weldments to the side fuselage.
• Open fuel vent hole in side skin/gear web to 1".
• Open brake line holes in bottom skin to 5/8" (Align with gear weldment). 
• Open fuel vent holes in bottom skin to 7/16"

With everything taken apart

• Drill the 5/8" rudder cable holes in the F-902 and F-724 bulkheads. 
• Drill the static line holes in the F-724 bulkhead.
• Finish strengthening and drilling the armrests.
• Finish rough-in of the side steps (I'm contemplating on when to do this...now, or when I flip the fuselage....I hate working upside down).
  
• Finish installing the 6 rivets in the firewall.
• Complete the edge roll to the bottom skins/side skins.
• Finish drilling the holes attaching the tabs of F-724 and F902 bulkheads to the longerons.
• Prep the baggage are panels, etc for nutplates (All panels are removeable).
• Debur, edge prep, countersink etc. 
• Prime
• Install the nutplates as called for in the plans and also for the baggage area removable panels.

 Well....time to dive into it.

The first item of business I dove into was to finish match drilling everything. I started at the center of the seat ribs and worked outwards.

 

There is just a ton of cleco's 

Next, I decided to tackle strengthening the arm rests. Yes, it wasn't on my primary to do list, but I think it will be a fun one to do. Material selection was a tough choice. Lots of opinions out there. I want good strength but not with too much a weight penalty. I opted to use 3/4"x3/4"x1/8" thick angle. About the heaviest material out there! Ha Ha. But I do intend to try to cut it down and drill lightening holes to help with the weight. So the angle to start with weights just over 200 grams each side. 

Now I clamped the angle to the work table and used a router with a small radius round over bit to put a radius on the vertex of the angle. Does the aluminum dull the router bit....Yeah probably. Does it do an awesome job, heck yeah!.

With the edge finished, the part nests nicely into armrest. Weight is now reduced to 195 grams. Next, I want to trim the flange of the angle that sits proud of the armrest.This takes a bit of time and work to get trimmed and smooth, but the result is fantastic.

Weight now drops to 173 grams

I used the fan spacer and drilled the angles to the arm rests.

Finished the F-724 luggage bulkheads - 6 hours

 To make the new tabs/flanges for the F-724 bulkheads. I had drawn a template out and then used it to cut some aluminum pieces in 0.025" scrap. Same thickness as the bulkhead. Then I made a wooden bending template using the F-724 as a guide. The bends are at a bit of an angle.

Next I had cut off the old tab/flanges on the bulkhead and clamped the new pieces into place. I took some time to ensure a good fit. I clecoed all of the luggage panels into place to ensure everything was were it should be.

Once I verified a good fit, I was ready to drill the tabs via the bottom floor skin. The placement turned out perfect and it was apparent I can easily trim down the new tab.

Next I had marked a vertical reference line making it easier to adjust and locate the holes that I need to drill to set the proper height of the new tab.

Haha, oh dear. I solved one edge distance problem on the bulkhead to have another pop-up. Not a whole lot I can do with this one. There seems to be a few of these coming up on the fuselage lately (The top most hole in the side skin attaching to the firewall).

I drew reference lines and centre lines on the new tabs and used the rivet spacer to transfer rivet holes. (I used the spacing of the rivet line that attaches the side skin to the F-724 bulkhead).

Next, I worked on locating the hole on the top tab of the bulkhead. Not much material to work with here. Edge distances are met. I used the dimensions noted in the plans. I've heard other builders have used an AN3 rivet here instead of the AN4 rivet just to minimize any edge distance problems. I figure why not...I can always drill it out and go to a larger hole/rivet down the road if needed.

I clecoed the assembly back in place, got things lined up and used the 90deg drill to finish the #30 holes into the bulkhead.

Fitting the baggage bulkheads - 4 hours

 I was curious this last while about just how straight the fuse was. When working on the forward fuse and crawling in there doing all the building I've bumped the fuse a number of times. So I set up the laser level on the garage door to shoot a center line. Well...To my surprise and delight it was spot on, so its a piece of mind that I can forge ahead confidently. 

 Now I need to fit the baggage compartment bulkheads. I started in on fluting the curved section of the F-722 bulkheads and then the F- 723 bulkheads. Then I was ready to cleco them in place. 

 

First step I drew a reference line on the tab of the bulkhead that meets with the longeron. I'll need to start figuring out the correct placement of that rivet once I have the bulkhead removed. 

Next I had a good look at the flange/tab that is to mat with the F-623 rib. Lots of builders talk about a gap here and sure enough, I too have a gap but nothing that a 0.063" shim won't take care of.

Before I started to cut a shim, I marked the rivet holes from the bottom skin onto the flange of the bulkhead. Yup, same as many other builders I too have a questionable edge distance on the inboard rib. 

This snafu was in the back of my mind reading other build logs. So it was an easy decision for me to choose making a new flange rather than just use a shim. A new flange with solve both the shim and the edge distance issue.

Finished drilling the outer floor stiffeners - 2.5 hours

 I managed to get the outside two floor stiffeners placed and drilled and not a task that I enjoyed. To start, I double checked the correct center by installing the F-982 coverplate. And sure enough Vans wants the "Centerline" to be drawn based on the dimension of the inside face of the web (3/4"minus thickness of the web) and not based on the full width of the angle (3/4") Insert eye roll here.

Once the 'Centerline' is transcribed on the back of the angle. Now comes the tricky part. Its easy enough to secure the aft end of the stiffener at F-704 bulkhead. I used a block of wood as Mike Bullocks build log

But getting the front end of the angle set is tricky as there is nothing to secure it with. So with the help of lots of tape and my kids holding from below, I managed to get it. Not only is it tricky to get the centerline aligned with the holes in the floor skin, but it is critical to get the whole angle placed forward and aft correctly to ensure proper edge distance on the ends of the stiffener. Drawing edge distance lines on the ends helps with this, but makes placing the angles correctly much more finicky.  

Finished drilling the center two floor stiffners - 1 hour

Not much time to work on the build this week. Fall is coming and the leaves are starting to turn color so I need to get some yard work done. After a long day in the yard, I snuck into the garage and finished the vertical #30 holes in the floor stiffeners. The 90deg drill from my buddy Mike works excellent!