Rudder hinges

Rudder hinges... how hard can it be? Right? Hahahaha!

First off - why you shouldn't alodine these hinges:

The plans call for MS20001-5 hinges. Aircraft Spruce sells them in 3 ft and 6 ft sections. I ordered a 3 ft section, cut them down to the 'High Performance Plans' specs (two 4" and one 6" for each rudder). I then thought - "Hey, they are aluminum, I should use alumiprep and then alodine them." So I took the time to do so - but after a normal 5-min bath - the hinges were not getting that bright golden color I was used to seeing when alodining other aluminum parts. Thinking that perhaps my alumiprep and alodine were weak from sitting on the shelf for almost a year, I then tried redoing the process, but this time letting them soak in the baths for 45 minutes (this trick has worked before). But still, the golden color washed right off when rinsed with water. A voice in my head said "Just install them on the rudders already!" But I needed to get to the bottom of it! I went home and began doing some research - turns out if you look close under the "Overview" tab on Aircraft Spruce's page for these hinges - you will see "MS20001P aluminum hinge is extruded. The closed hinge loops cannot be pulled apart. Furnished with hinge pin. Anodized finish." KEY WORD: ANODIZED! So then I began to question - can you alodine an aluminum part that has been anodized? I searched the internet high and low and couldn't find an answer. Finally, I called up the manufactures of Alodine and spoke to one of their technical reps - (supper friendly by the way!). Long story short, alodine won't do anything to anodized aluminum - the alodine simply won't stick. HOWEVER, he warned that the alumiprep acid might have etched the anodized aluminum. In other words, I might have removed portions of the anodizing when I soaked the hinges in the alumiprep bath for 45+ minutes! I hung up and yelled a few expletive words out into the air, went back to ACS and ordered another 3 ft section. Not the first time I flushed money down the toilet while working on this project!

CASE AND POINT: these hinges come anodized and so do not need to be alodined! Moving on!

So I cut my new 3 ft section of piano hinge into the two 4" and one 6" sections for each rudder..

Next, I used clamps to hold them onto the rudder. I should note that I made sure the rudder's leading edge was perfectly straight (using a straight edge and lightly sanding them where needed). Also did this to the winglet's trailing edge and made sure the rudders and winglets mated perfectly in line with no gaps in between.

I used a spare piano hinge pin (3 ft long pin) to pass through all three hinges at the same time. This helped make sure that all hinges were perfectly in line.

I then removed the hinges, and marked their locations. Because I am not installing the bottom winglet and also installing hidden rudder belhorns, my lower 6" hinge is located slightly higher than per plans. I also marked the rivet locations.

Top hinge location and rivet locations...

Attaching the hinges to the rudders: CP#41 LPC#118 warns us that the sketch in the High Performance Rudder plans on page R2 (top left hand corner) is wrong. The hinge should be permanently mounted into the rudder with rivets, and the attach screws and nutplates should be in the winglet. 

Since the plans say to use Cherry BSC-44 pop rivets, I drilled out the #30 size holes... six holes for the 6" hinge...

And four holes for the 4" hinges...

Since BSC-44 rivets are countersunk, I used the corresponding 120 deg countersink...

I then reclamped the hinges back onto the rudder and match drilled with the #30 size drill bit...

I then inserted the BSC-44 rivet...



Made sure it was flush with the surface...



And used the pop-rivet tool to install it... making sure it was perpendicular with the surface (otherwise you end up with a not so flush rivet head!) I was just posing for the picture here.. but when I commit to installing the rivet, I use my free hand to hold the rivet tool down onto the surface.




I repeated this for all remaining rivets... making sure the hinge was aligned throughout the process. In hindsight, I wish I would have sanded the back lip of the rudder's leading edge to a 45-degree ramp. This would have tucked the hinge in deeper, creating less gap (I will explain this in further detail later on when I show how I installed the hinges onto the winglets).

All three hinges installed on the rudder!

With the hinges installed on the rudders, it was now time to install the rudders onto the winglets!

First step was to hold the rudder in place and mark the hinge locations...

Zooming in, you can see where I marked the hinge location - following the aileron plans, I made these pockets 0.2" deep.

These pockets get cut out and allows the hinge to get tucked in place..

I first started to mill this out with a dremel.. and then realized it was much faster to trim it with the multitool...

And fine tune it with a metal file...

At this point, I was wondering how the pin in the hinge stays on. So I reached out to Long-EZ owners and asked. Answer: they get locked in place by the very same pocket that the hinge resides in. So I marked the pin with a pencil...

And took it to the bandsaw. When I cut it to length, I noticed that the bandsaw automatically created a small bulge at the end of the pin.

Zooming in, you can see the bulge...

This bulge is perfect for keeping the pin from sliding out the bottom while installing the rudder (so I kept the bulge end of the pin at the top end of the hinge). The 0.2" pocket will keep the pin from sliding up and out. Notice the bulge is so tiny it is hardly noticeable when installed...

Showing how the hinge pin gets locked in place by the hinge recess...

After cutting the 0.2" pockets for the hinges, I ran into an "oooops!" moment. Looking back at the plans, it says to make the rudder and winglet pockets approximately 1" deep. I remember taking the time to measure the piano hinge open width (1.75" wide) and thinking, "If half of the hinge goes into the rudder and the other half goes into the winglet, 1" deep pockets for the rudder and 1" for the winglet is plenty!" So I made both 1" deep and ignored the "approximately" part. HOWEVER, I did not account for the 0.2" recess to tuck the piano hinge in, and also for a small rounded corner that is created from transitioning the fiberglass from the pocket back-wall to the pocket side-wall. This meant that although I cut the 0.2" pockets, the hinge bottomed out and could not be recessed any deeper!

Hinge bottoming out at the winglet's back-wall...

So I had two options: 1) mill out the fiberglass pockets of the winglets, make them 0.25" deeper and re-glass them... or 2) cut 0.20" off the hinges lengthwise.

After making a few mechanical stress calculations, I figured removing 0.2" was the way to go!

I measured 0.2" on all the winglet side hinge tabs...

And trimmed away using the bandsaw!

This allowed me to tuck the hinge into the 0.2" recess without bottoming out... giving me a much better fit!

But now there was another problem... even with the hinge butting up against the 0.2" recess, there was still an obvious gap between the rudder's leading edge and the winglet's trailing edge! The gap was consistent all the way along the edge... so it wasn't that the edges weren't straight.. 

Here is the bottom hinge... 

And also at the top... notice the gap between the rudder and the winglet... also notice how the trailing edge of the rudder does not line up with the trailing edge of the winglet...

This meant I needed to tuck the hinge in a little deeper. Not wanting to remove too much material from the 0.2" recess, I penciled in a straight line, and sanded away until I could barely see the pencil line... first with a dremel and then fine tuning with a metal file...

Much better!! Notice no gap between the rudder and the winglet!

All along the rudder hinge line... and now the trailing edges line up! Much better!

But then I noticed ANOTHER problem! While I was able to tuck the hinge into the recess.. I noticed the hinge was now not wanting to remain flat with the winglet's inside wall surface! What was going on here?!

So if you look closely at these hinges, you'll notice that they ramp up into the hinge loops.

This "ramp" was acting like a wedge, and not allowing the hinge to sit perfectly flush with the surface!

So I used the dremel to sand a 45 degree ramp on the winglet hinge recess...

This is the BEFORE pic... where the hinge loop ramps butt up against the winglet pocket's trailing edge...

This is AFTER using the dremel to sand the winglet's inside pocket's trailing edges at a 45-degree ramp... notice how the hinge loop ramps now have room to slide under and tuck all the way in, while remaining perfectly flush with the surface!

Hard to see in this pic but there is now a 45 degree ramp on the winglet's inside pocket's trailing edge...

With the hinge pockets fine tuned to perfection... it was now time to drill the holes to mount the hinges...

I measured the hole locations so that they would be in the middle of the hinge tab... three screws for the 6" hinge...

And two screws for the 4" hinges...

I needed to hold the rudder in place while I match drilled the winglets.. having someone helps, but since I was flying solo, I used wood wedges to hold the top and bottom hinges in place...

After making sure the rudder was exactly where I wanted it, I melted hot glue gun sticks with a lighter, and dabbed blobs of hot glue gun to the top and bottom of the hinge tabs to lock it in place.

I then removed the wood wedges and swung the rudder out and in, making sure it was perfectly aligned. After approving its location, I match drilled a hole at the bottom hinge, keeping pressure on the hinge tab from the inside - since the hot glue gun isn't strong enough to handle the drilling forces.

First a pilot hole...

Since the plans calls for AN525-10R8 screws, I then opened them up with a #10 size drill.

I inserted a screw through...

And temporarily tightened it down in place using a regular nut.. this was to make sure the hot glue gun wouldn't come undone and dislocate the rudder while I match drilled other holes.

I only did this for a single screw for the bottom hinge and a single screw for the top hinge. I wanted to remove the hot glue gun blobs before match drilling the rest of the holes.

So I then removed the rudder (much easier to do with the hot glue than it would have been with Bondo!)...

Also, the hot glue gun blobs remove much easier than if I had to clean up Bondo blobs! A simple spatula removed the blobs in 5 seconds!

I then reinstalled the rudder (using the two holes I had match drilled) and match drilled all remaining holes - hot glue gun free!

It was now time to install the K1000-3 nutplates onto the hinge tabs. I started out by removing the tabs from the hinges. I then temporarily fastened the nutplate onto the hinge tab using an AN525-10R8 screw (notice I used washers so that I wouldn't have to tighten the screw all the way through - those nutplates are very tight and require a lot of torque!) Also, notice the nutplate is installed on the opposite side of the tab for now. This is done intentionally and I'll explain why in the next pics..

Temporarily installing the nutplate on the opposite side allowed me to match drill the nutplate with the hinge hoops faced up - which allowed me to lay the hinge tab flat on the table (actually a scrap 2x1 so that I wouldn't drill into my workbench!) You can't really see it in this picture, but I cut a hole into the 2x1 so that the screw holding the nutplate in place would not interfere.

After match drilling one hole of the nutplate, I inserted a rivet - using it as a cleco to keep the nutplate from rotating and keeping it in the correct orientation...

I then removed the nutplate...

Nutplates are easily installed using MSC-32 pop rivets (now CCC-32 rivets). They require a 120 degree countersink with a #40 pilot.

So I countersunk away! Notice I made sure I was countersinking the correct side!

Making sure the rivet was flush!

Pop rivet tool! I love this thing!

Nothing fancy here, I simply placed both rivets in (helping me align the nutplate exactly where it needed to be)... and I riveted away!

Taaaa-daaaaa! Nutplate riveted in place! Now to repeat this process 13 times (14 total!) since there are 2 screws per 4" hinge... and 3 screws per 6" hinge...

Notice the rivets are flush and do not protrude out, allowing the hinge tab to sit perfectly flush when bolted to the winglets!

Test fitting the screw to make sure the nutplate was properly aligned...

I then reinstalled the tabs onto the rudders. Don't panic! The tabs are not bolted to the rudders! I simply flipped the tabs (of the winglet side) up over onto the rudder's outside face...

I then reinstalled the rudders.. only this time I used the actual nutplates attached to the hinges!

Bottom hinge...

Middle hinge...

Top hinge....

Inside pocket view of the bottom hinge (the 6" hinge)...

Inside pocket view of the top hinge (the 4" hinge)...

Notice the trailing edge perfectly aligned!

And there you have it! Rudders are installed!