Before attaching the trim tab to the left elevator. It is best to fix the bend tabs of the left elevator skin.
I made a centerline on the outer tab and fixed 2 points to drill. There are no real dimensions given for this on the plans. I made my first hole near the bend in the tab and another one around the middle.

Don't drill just yet.

First clamp both sides of the elevator skin well against the E606PP trim spar. You want to make sure that the distance is right.
Then drill the holes for the MSP-42 pop rivets.

Once the holes drilled, deburr them and install the pop rivets. Now you are sure that the tab ears hold well together and won't move anymore.

The main reason why to do this first attachment first is to ensure you can measure correctly the minimal 3/32" clearance between the trim tab and the left elevator.

Then I completed the trim tab itself. I still had to rivet the E-721 piano hinge on the top side and set the poprivets on the sides.

Drilling and setting the CS4-4 pop rivets on de sides is easy. Make sure you do the drilling of the holes before rivetting the trim tab spar in the trim tab.

You still need access to deburr and dimple the holes as the they are countersunk pop rivets.

After setting the pop rivets, I touched them up very lightly on the scotchbrite wheel near the center to smoothen the left over of the broken nail.

I think they came out pretty well and the overlap on the tab ears is smooth and thight.

With all this done, It's time to attach the trim tab to the left elevator. This is a painfull job that requires a lot of patience.

Run a long aluminium angle along the bottom aft edge of the elevator and position both trim tab trailing edge and elevator trailing edge along the straight line of the angle.
Also adjust the inboard side of elevator and trim tab side to ensure the minimal 3/32" gap.

Drilling the first holes is really nerve cracking as you can't really hold down the hinge to the elevator trim tab spar while drilling.
I marked the first hole with a pen and then drilled the first hole under the drill press. That would at least already position one hole correctly.
The second one on the other side, I drill immediatly on the assembly. There is still some room for play with these 2 holes drilled but it's not much.

Sight down the trailing edge to verify the straight line.

Once the 2 holes are drilled, things get much easier, as you can gently flip up the elevator to hold the hinge from below while drilling.
In the picture below, all holes are drilled.

 Deburred the hinge and now ready for rivetting:

Set the 4 poprivets outboard side of the E606PP trim spar. The MS319BS rivets will not fit in the #40 drilled holes. You will need to enlarge the hole to #33.

The E-721 piano hinge rivetted in place:

Look ! No clecoes on the top  :) The alignment came out really nice. This was a step I postponed for a long time and I was afraid of doing i but it worked out well in the end.
The only thing I'm still not happy about is that the height of the hinge on tab side is smaller then on the elevator on the bottom side of the elevator. I contacted Vans about this.

They told me it would not influence the flying characteristics at all. The tab and elevator will almost never be completely aligned in flight. 

Nevertheless, it is not to win a beauty contest. Hapilly it's on the bottom side.

Next step is the installation of the electric trim motor on the trim tab.

I started by marking the two lines on the E-616PP cover plate as indicated on the plans. When test fitting the motor on the Z-angles on the plates, I soon found out that these dimensions would not give me a perfect fit for a straight line on the push-rod between motor and tab hinges. Therefor, after a lot of trying, I marked the position of the Z-angles by hand on the cover plate. As you can see, the best position is a bit more to the right then marked on the plans, the z-angle is also slightly turned to the right instead of following the straight line.

I also have to cut of a little bit of the z-angle foot to maintain the full opening.

Drilled the Z-angles EET602B-L and EET602B-R to E-616PP

Rivetted the Z-angle.

The front rivets will interfere with the motor block. I returned to them after taking these pictures to set them a bit (flatter). It was better but still they interfere. I might be using a washer under the motor attachment on final tuning.

Temporary installation of the motor using the full length push rod. As you can see, the alignment is nice and straight to the trim tab hinge.

The insertion of the motor is difficult. You will have to grind away the side parts of the platenuts that interfere with the opening. Otherwise it's almost impossible to insert cover and motor. 

The wiring goes through the back through the front spar of the elevator. There is a hole foreseen already. Run a bushing through it to protect the wiring. Also the vise that runs in and out of the motor for the pushrod comes out here. 

I think this is a weak point in the design electric cabling and mechanic part through the same hole is a potential for problems. Maybe I'm missing something. I'll get back to all of this on final assembly and tuning of the trim tab.

Then I cut of the push rod measuring according to the center motor position and the elevator centered. The rod length should be somewhere around 3 1/8 inch.

Installed the clevis pins and tested the motor using a 6V battery. I get a deflection of 20° up and 20° down.

The manual states the max elevator ranges as 25 up / 35 down, which is a total sweep of 60 degrees.You will never reach this with this type of motor as the total range is only 40-45 degrees.

I tend to go with the  30 up, 10-15 down compromise as I believe that the trim tab down (nose trim up) which is most used in landing is more important then the trim tab up (nose trim down).
On the other hand, I have been reading on forums that most people say they never need to use more then 10° deflection on the trim, so this might be a theoretical case anyway.

For the moment, I'm leaving it to 20/20 and will return to this tuning upon final assembly.

The finalised install looks like below. It is really rewarding and satisfying to play a bit with the battery and the push knob up and and down once it's installed.

It's time for the inspection now. Once that is done, I can rivet the remaining parts, include RTV in the stiffeners and secure the hinge pin.