Category: Trailing Edge

Continued installation of left lower skins

January 20, 2012 – We continued to install the lower outboard skin on the left wing. The flap brace is completely installed, and I installed the hinge pins. They were a pain with the wing in the cradle, but I know they’ll be easier when the wing is horizontal and low to the ground.

We also got the pitot mast installed. I sealed it in place, as well.

We should have the left skins installed in just one more session, then we get to do it all over again.

Time: 4:40

Installed nutplates for flap hinge pins

November 21, 2011 – I have finally installed the nutplates that will secure the flap hinge pins. I got the right one done several days ago, but as soon as I installed the second rivet, I realized that I had installed the nutplate upside down. The big issue was that I had countersunk the rivet holes in the flap brace.  STUPID!!! So after I calmed down and regrouped, I made a doubler and installed it. The countersinks are now on the correct side and the nutplate is installed.

Time: 2:00

Flap hinges drilled and hinge pins bent

November 15, 2011 – Once I got the wing-side flap hinges in place with Carlos’ help last week, I continued to drill the hinges.

Because I had inadvertently dimpled the flap braces (where the flaps attach to the wing) I had decided to countersink the hinges to clear the dimples, then install a strap to add strength. The straps would also help make up for less-than-ideal edge distance on the hing half.

Hree’s the countersinking in progress. You can also see how close the edge distance is from the holes to the edge of the hinge.

Once the hinges were countersunk, I clecoed them back in place and drilled the straps. I think this will work out fine, and will provide additional strength.

After the hinges were drilled, I started making the hinge pins. I chose to go with the option of having two pins per flap, each fed from the center of the flap. I temporarily placed the flap in place, and marked where the hinge cutout was so I knew where to bend the pins.

I bent a 90-degree angle in the pins, then went approximately .7″ from that 90-degree bend and bent a 45-degree angle in the correct direction. I made sure the pin was in the correct position and had pin to spare on either end. Here’s the first pin bent and in place:

…and the second:

I cut pieces of leftover hinge, which will be secured to the flap brace with a screw and nutplate. This will lock the pins in place.

Time: 3:55

Started drilling flap hinges to wing

November 7, 2011 – Over the last week or so I set up to drill the flap hinges to the flap brace on the wing trailing edge.

I decided to cleco the bottom wing skins into place. I’m REALLY glad I did because I found out that the flap braces are not necessarily in the correct position to align the flaps with the ailerons when attached, as seen below:

If I had clamped the flap to the brace, then adjusted to the aileron, it would have been way off.

My next problem was how to hold the skin and the brace together so I could also clamp the hinge in place to correctly drill it. I had read about how other people used rivets to temporarily hold everything together, but it seemed that some of those people went overboard on the size of rivets they used for this. I picked four spots along the brace where it seemed that a cleco did the most good keeping everything tight and aligned, and I laid out rivets at those locations. I’m just using the same -3 rivets that will be used to rivet everything together at the end. I countersunk the skin and used a short rivet to hold the flap brace in place.

When I rivet the hinge in place, I’ll just shoot these like all the others. I don’t believe the countersinks in the skin will pose a problem, because those are surrounded by regular dimpled holes, and I’ll also be putting a strap on the backside. More on that later.

A friend of mine from work, Carlos, came over to see the project and to give me a hand with the alignment of the flaps for drilling. I tried to handle it by myself, but the fine adjustments were a pain, and I was afraid I’d drop a flap.

I had drawn the line along the hinge at 1/4″ as a guide for edge distance. With the trailing edges aligned, we were on the low (edge) side of that line. A little less edge distance than I would like, but again, I’m going to put a strap behind everything, so I’d have extra structural support. We placed a small c-clamp at each end and did the adjustments as needed.

The plans call for a 1/4″ gap between the flap and the aileron; other people have gone with 3/16″. I decided to split the difference and got a nice 7/32″ gap.

The trailing edges in that picture don’t appear aligned because the flap is not held in trail with the aileron.

When we were happy with the positioning, I drilled a couple of holes on each end, just to hold it all in place. Here’s the outboard and the inboard clamp setup:

I removed a flap to expose the hinge and make it easier to drill the rest of the holes.

Thanks Carlos!

Time: 4:40

Installing trailing edge fairings

June 8, 2011 – I’ve deburred, cleaned, primed and installed the aileron gap fairings and the left flap brace. It’s been hot here, so I try to get done what I can as early as possible, and I’ve been quitting around 1 pm.

On the right wing, I realized that I still had to install the five rivets in the skin at the very inboard end at the aft spar, where there is the buildup for the spar attach. So Joe came over and we knocked those out. Now I can install the right flap brace, and then I can start on the ailerons.

On a side note, I found an ad on Vans Air Force for a tail strobe for $60. I jumped on that. Now all I need is a steal on a pitot tube.

Time: 6:05

Attached aileron hinge brackets

June 4, 2011 – Well, the date is misleading, but the work goes on. When I was ready to do this update last week, my hard drive died, so I haven’t been able to do this until now.

I finished the aileron hinge brackets and riveted them to the aft spar on both wings.

In the previous post, I had painted all the parts for the hinges. I assembled each bracket on the table.

Then I clecoed each one to its respective position. The outboard hinges also get riveted to the outboard ribs, so I drilled and deburred those holes, then clecoed them in place. In my constant effort to go overboard, I used sealant when assembling the brackets, and when installing them on the spar.

I then riveted all the hinges.

The next step is to install the flap braces and aileron gap fairings.

The flap braces get trimmed where they fit over the doublers at the inboard end of the spar. There are guide holes in the parts, where you remove that small section of material.

I then cut both flap braces on those lines.

I test-fitted the four pieces on the aft spars. I’ll remove and clean them up this week.

Time: 4:55

Prepped and painted aileron hinge brackets

May 25, 2011 – Over the last week or so I’ve worked on the aileron hinge bracket assemblies.

I assembled them all using clecoes and I test-fitted them on the aft spar.

Here’s the outboard and how it fits:

And the inboard. I discovered that I’ll have to slightly modify the brackets to clear a fastener through the skin at that point:

When I clean up and deburr pieces that layer together like these do, I usually clean the edges as a unit. So while they wre clecoed together, I polished the edges using my usual Scotch-Brite pad in a die grinder. This aligns all the edges together. I just sanded the corner to clear the rivet and rounded that lower edge so the bracket fits nicely in the radius.

I took all the pieces apart, keeping them in groups. I cleaned and alodined them all, then primed.

I’ve read that primer in the counterbored hole for the bearing interferes with that bearing, so I found a socket that fit the hole, and rolled it in tape to fit. I placed the socket in each hole as a mask, and painted. The holes came out nice and clean.

Time: 2:05

Started ailerons

May 17, 2011 – With the top skins on and the wings in the cradle, it’s time to move on to the next thing.

I started working on the ailerons today. The plans call for the brass bushings in the bellcranks to be no more than 1/64-1/32″ longer than the bellcrank tubes. I had to remove 1/32 from each bushing to make it 1/32″ longer. I also reamed the bushings to .248″ That allowed a nice fit for the bolt.

I then installed the bellcranks in each wing.

I then laid out the parts for the aileron hinges that attach to each wing. I’ll clean these, then paint them before assembly. These brackets will contain a bearing for each end of the ailerons.

Time: 1:00