458.5 hours-Turned center bearing drill guide and trimmed HS tip skins

I rRead some disturbing posts on VAF today that talk about the steps that I am about to perform on my own build. Seems that there is quite a bit of a problem with the elevator trailing edges and counterbalance skins having a bit of a twist or a misalignment problem. I called Vans today because I wanted more information to clarify their instructions which say to place the elevators "in trail" with the HS and then check the alignment of the counterbalance arms with the HS. Many builders interprest this to mean that you clamp the counter balance arms to the HS and that means that the elevator is now "in trail."

Well, I confirmed with Scott at Vans today that the true meaning of the term "in trail" is based on the extended chord line of the HS with that of the elevators. Problem is that it is difficult to determine where the chord line actually is without some reference point, which Vans does not provide in their plans. So most builders use the clamped counterbalance arms as the point where both parts should be "in trail.

Since I still had some excess skin on the HS that captures the counterbalance arms of each elevator and holds them in place, I did not need to clamp anything down just yet. At first glance it looks like everything lines up real nice, but then I got out a long piece of aluminum angle that I know is very straight. I laid it across the left and right elevators along a line that is just forward of the rear trim tab spar on the left elevator. I was shocked at how far off level the angle was. This can unfortunately only mean one thing - that my elevator trailing edges are horribly misaligned, similar to what others have experienced.

Next comes the sad story of how to resolve this problem. The possible solutions range from the following:

1. drilling out the tip rivets, repositioning the counterbalance skins and elevator skins at the tips, drilling new holes for oops rivets, and re-riveting everything.
2. Setting the elevator trailing edges so that thet are even with each other by using a laser level or other device, and leave the offset counterbalance arm "as is." This is the recommended approach.

I won't know how bad everything is until I get the excess skin of the HS tips trimmed away so that the elevators can swing freely. My fear is that the elevators are so badly out of alignment with each other that the control horns will be so badly displaced after aligning the trailing edges that there is no way that I will be able to drill the center bearing holes in each horn without running out of edge distance on at least one of the them.

So I decided to continue moving toward the inevitable by slightly reducing the aluminum drill guide bushing circumferance so it would fit inside the center bearing on the HS. It ends up being a bit too wide to fit inside the center bearing, even though it was advertised as having a 1/4 inch OD, which is supposed to be the same diameter as the bearing. I reduced it to proper size by chucking it in my drill press and turning it against a small piece of emery cloth. I did this several times, trial fitting the bushing inside the center bearing several times until it just slides snuggly through the bearing hole. This worked out fine. Here is the pic of the bushing inside the bearing with the #27 drill bit in position to drill the hole in the control horn when the time comes.

Here is a pic I promised of the clerance between the edges of the HS skin and the counterbalance arm of the elevator - it is about 1/8 inches and is fairly consistent. It also shows the amount of overlap between the forward portion of the counterbalance arm of the elevator and the tip of the HS. This excess skin needs to be trimmed away to allow the elevators to swing freely.

And here are the marks I measured for the cut on the excess HS skin. The plans call for a minimum 1/8 inch gap between the HS and the forward portion of the counterbalance arm. There will also be a 1/8 inch radius on the inside corner, similar to what I did for the removal of the material from the rear spar from the last post.

This time I decided to use the 1/4 inch drill bit to drill the hole without all the upsizing from smaller to larger bits. I started by center punching the mark for the hole, and hand turning the drill bit until the hole was established. Then I ran the drill to finish the hole.

And the finished trim job after cutting out the excess with the dremel cutoff wheel and filing the edges clean with my small file set.

I flipped the HS over and need to reinstall the elevators one more time to mark the cut lines for the other side of the HS. I will finish those tomorrow. Right now I am just sick to my stomache at the thought that these stinking elevators are probably notr aligned very well with each other. If that turns out to be the case I will no longer be a fan of computer aided matched hole concepts and will resign myself to jigging just about every assembly from here on out. Once the excess skins is removed from both sides of the tips of the HS I will be able to clamp the elevators in place, set up my laser level for the trailing edges, and the go throught steps to determine just how far out of whack everything rfeally is. Right now I am expecting somewhere between 1/4" to 1/2" offset, based on the results of my test with the angle laid across both elevators in the supposedly "in trail" position.

457.5 hours - Reamed the holes in the HS hinges and mounted the elevators -VERY COOL!

There is no better way to spend a leap day during a leap year than doing what I did today, at least as far as I am concerned anyway! This was  fun evening for change. I started by running over to A&A Tradin Post to get a #13 drill bit. I drilled out the hinge holes with this bit first, and followed it with a #12 reamer. I was mostly removing powder coating from the hole, but it did trim some metal as well. Then I trial fitted the mounting bolts in the holesv-everything fit as expected.

Then, after reading pertinent sections of Steve Riffe's builders log for this part of the empennage build, I noted that he had set the rid end bearing measurements on his elevators to 27/32 inches from the spar web to the center of the rod end bearing hole, or the bolt if you prefer. A common practice when a range of measurements is provided, i.e. between a and b, is to split the difference in the range and use that as the target value. In this case, as I stated in my previous posts, The minimum measurement is 13/16, or 26/32 inches. This is how I had set my bearings the other night. The max range on the plans is 7/8 inches, or 28/32.

Steve simply split the difference between the min and max values and set his to 27/32. After reading several recent posts from builders having problems with the LEs rubbing against the edges and rivets of the rear spar of the HS, I decided to adjust mine outward to the same measurement that Steve used for his. I have found that 1/2 of a full turn of the rod end bearing is equivalent to moving it in or out 1/32 id an inch. So I unscrewed each of them out 1/2 of a turn and that took care of it.

Here is shot of my non-scientific bolt centering method for measuring the rod end bearings:

Ya hold the bolt with one hand and measure with the other with the bolt parallel to the spar web and the rod end bearing as straight up and down inside the cutout as possible. Worked very well for me.

Next is the #13 drill bit and the #12 reamer I used to clean out the hinge holes. Sure glad I got this right the first time. That episode with the rudder still gives me nightmares.

Next are some really crappy pics of the marks and pilot holes I drilled in the bottom flange of the rear spar to provide the clearance for the downward movement of the elevators.

I used my nibbler tool to cut away the sections of the flange, and then used some small files to finish the edges and the inside radius. Turned out OK. I will apply some primer and smooth the edges with aluminum oxide sand paper, not in that order of course.

Then I enlisted the help of my son to slide the elevators onto the hinges and install the temporary hinge pins so I could get an idea of several things, including the clearance between the end of the HS and the counterbalance arm of each elevator, the clearance between the leading edges of the elevator and the rear spar of the HS, and the in trail alignment of the elevators with the contour of the HS. On all counts it looks pretty darn good to me.

Next is the alignment of the control horns. I too experienced a slight offset of the contour of both control horns, and it seems that one horn is spaced a little bit further apart from the center bearing than the other one. But other than that everything looks to be close enough to work with, so I am happy with it so far. I will have to put together the right quantity and size of washers on the center bolt to ensure that they fill the uneven gaps correctly, but this is also expected and is normal.

 

 

On this last pic you can just see the forward edge of of counterbalance skin tucked in between the top and bottoms skins on the end of the HS. This is the excess skin that has to be trimmed away. I am hesitant to do this prior to drilling the holes in the control horns for the center bearing bolt, because this seems to keep the elevators in the proper "in trail" position. I will of course also clamp them down to ensure they do not move during the drilling. I will ta to Vans tomorrow to see what the recommended procedure is.

At some point I need to trim away the excess skin so that I can check the range of motion, and also for any binding or rubbing of the elevators against the HS. Looks like I am missing some pics of the tip clearance so I will get those and post them tomorrow. I wish there was a more precise way to confirm the real "in trail" position of the elevators. I will have the same issue when I fit the ailerons to the wings. Maybe a string along the cord line or something like that.

Anyway - it is starting to look like the back end of an airplane at least. VERY COOL!

456 hours - pulled down the lonely HS - Prep for fitting the elevators

Managed to get the HS down off the wall all by myself. No new dings as far as I am aware. I forgot just how large 8.5 feet is. Lots of dust to clear off, and everything needs a good cleaning. As soon as I started looking it over, I started having flashbacks to all the "moments" during the HS build where things did not go exactly according to plan. Of course there is the major ding on the top skin, the major forward spar repair, the hard-to-set forward rivets on the tips, Several smilied rivets, and many scratches, dings, and just plain not very good workmanship IMHO. I did not even ground down my soldering iron well enought to remove the vinyl coating around the rivet lines, so I also have several small scratches in the skins as a result of that. Then there is all the divets and scratches from bad flush riveting where the mushroom rivet set in the gun has either dented the skin around the rivet hole or severaly scratched the alclad surounding the rivet. Not very impressed with the exterior of the HS to say the least.  Oh well, I will let the tech counselor rip to shreds when he comes to visit, and go from there.

A reminder to other builders - make sure you disregard Vans build sequence they have laid out in the plans, and START WITH THE VS FIRST INSTEAD OF THE HS! The HS is NOT the best thing to start with, as there are many complex steps involved in this part of the build, the parts are smaller, and you have to build two sections. The VS is a much better build for learning how to handle all the new tools, clamping procedures, and riveting/bucking techniques. Also start off right and grind down the edges of your yokes and any other tools that do not have correct clearance. In the world of flight instruction, we have a saying:

Do not let the airplane fly you - YOU fly the airplane.

This addage can also be applied very easily to building this kit:

Do NOT let the kit determine the quality of the build, YOU determine the quality by using the right tool for the right job, taking your time, and seeking assistance from other builders/chapter members when needed.

I may very well drill out the rivets and remove both HS skins and order some new ones, unless the tech counselor can convince me that this is not necessary. It would be a lot of work to do this, but I think the skins would turn out so much better now that I am a bit more seasoned as a builder

Here are the elevator leading edges sitting next to each other. I wanted to compare the contour of the rolls on each one to see how symetrical they are.

Next is the HS turned upside down, and the left elevator roughly placed into position so I can check some measurements and initial fit of certain areas.

Next is a pic of the center section where the elevator control horns sit next to the center hinge bearing, It also shows some lines I drew with a sharpee to mark the area of the bottom flange of the rear spar on the HS that must be trimmed away to allow for proper range of motion of the elevators when they are moved in the down direction. I set the length to 1 inch from the edge of the center bearing on both sides (26/32" is the minimum necessary to clear the flanges of the control horns on both sides, but I figured that rounding it to an even inch was acceptable. The depth measurement is 3/8". I have it on good authority from several other builders that this is more than adequate to allow for proper range of motion of the elevators. I will radius the hole 1/8 of an inch, which means a center punch 1/8 of an inch out from the inside corners to allow for a 1/4 inch drill bit which will create the 1/8 inch radius that I need. No such trimming is needed on the top flange of the HS rear spar, since the elevator control horns do not interfere with anything on that side.

You can also see the gap between the control horn and the center bearing. This is normal and will be closed up by adding as many washers as are necessary on the bolt between the control horn and the bearing on both sides.

And finally is a pic of the tip section. There is more trimming of the HS skin required in this area in order to clear the tip of the counterbalance arm. I will use the same process as I did for trimming the bottom flange of the rear spar of the HS. Only question is how much clearance to leave between the counter balance arm and the HS skin. I see absolutely no mention of this in the plans at all. It may be as much as 1/4 inch or as little as 3/32 inches. I'll have to inquire about that. Tomorrow I give the HS a bath and trim the flanges on the rear spar. I also need to go get a #13 drill bit which I will use to pre-drill the hinge holes on the HS, and will follow that up with a #12 reamer. Once the hinge holes are properly reamed to size, I can use the temporary hinge pins to trial fit the elevators and check for range of motion in both directions and binding.

You can see the slight overlap of the HS skin on the right side of the pic. This overlap will be much greater when the rod ends are inserted all the way into the hinges.

455 hours - finished riveting the LEs - Rod end Bearings, and Torque counterbalance hardware

Had to drill out a few rivets and re-do them. Obviously I fixed the pop rivet gun problem. That is honestly only the second time since I started this project that I experienced some sort of tool failure. Both of them were temporary and were caused by aluminum chips or fragments getting into small places - a good reminder to keep the shop as clean as possible at all times, which is something that I have not been doing lately.

Here is the left elevator all buttoned up

I used the torque wrench to tighten down the screws and lock nut to 25 inch pounds per the plans and torque specs for the hardware. This was also my very first time for applying torque seal to the nut and bolt. Got kind of messed up on one of them, but the rest came out OK.

NExt is a pic that shows the differences in the pop rivets I was using to close up the LEs. Still not sure if the one without the mandrel on the end is a defective rivet or not, but will call Vans tomorrow to discuss. The other mandrel in the pick that still hS the head attaached to it is the one that pulled completely out of the hole without breaking. The remaining "debris" is some of the rivet heads and shafts that I had to drill out and replace. Thies rivets are pretty easy to drill out, unlike the one that had to do on the trim tab a while back.

Next are the rod end bearings - two for each elevator. Plans say to screw these in so that there is 13/16 " from the spar web to the center of the bearing hole. Some have devised very elaborate methods for doing this, but I found that an eyeball technique seemed to get me close enough. The real test will come after the elevators are installed on the HS. I took one of the bolts tat goes in the hole in the center of the bearing, inserted it in the hole, adn was able to hold it pretty stright by applying vcointer pressure against the back side of my finger on the edge of the elevator skin of the cutout, while pushing the bolt in firmly against the bearing, and checking the alignment ofd the bearing and bolt to see if it was parallel to the spar web. WIth the bolt held in position, I took my small ruler, butted it up against the spar web, and layed it over the top of the bolt shaft on the other side of the bearing. Then I read the measurement at the preceived center point of the bolt.

Not horribly exact, but good enough to get within a half turn of a rod end if the need arises, when I trial fit the elevators to the HS.

At this point I don't really want to call the elevators done yet, since some touch up primer is needed in a few places and some debris and shavings need to be cleaned out in certain areas. I will do this tomorrow, and then attempt to get the HS off of the wall. There is still some trimming and fitting and drilling to be done with the HS, but that should go relaitvely quickly.

I am a little leary about rushing this, however, especially after reading a recent post from a builder who wrote about problems with his RV 10 elevators rubbing on the inside edges of the rear spar rivets of the HS. This was possibly due to not setting the rod end bearings to the correct distance. Problem is he had also already drilled the holes in the control horns which pretty much sets the distance of the rod end bearings in stone. If you try to adjust them the center bearing will bind up. Another builder wrote that he checked everything thoroughly after the elevators were done, just as I am about to do, and everything seemed fine with the HS and elevators off of the  fuselage. But when he mounted everything to the fuselage he encountered the same rubbing problem.

I really want to make sure I do this correctly, so I will once again take my time and make sure that the rod end bearings are exactly where they need to be. I am not very convinced that my LEs are symmetrical or that each separate section is evenly shaped, especially since the process to form them is anything BUT precise. In the end I may decide to move them to the outer limit in the plans which is 7/8 of an inch, or about 1/16 inch more than the suggested measurement of 13/16 for the rod end bearings. Once you drill the center bearing bolt holes into the control horns you are committed. If you screw up the rod end bearing placement, you may very well end up building new elevators, or you will have to figure out how to repair, redrill, or replace the control horns - none of which I wish to encounter later on down the road.

454 hours - riveted leading edges of both elevators

Well, I have to admit, and any of you following blog site already know, that I seriously doubted if I was ever going to see this day arrive. I finally got to the point where it was time to rivet the elevator leading edges together for what I hope will be the last time for the rest of my natural life.

A new first was the use of a little present that I got from Mike Rettig a while back that I had not yet had the chance to use. It is a pneumatic blind rivet puller from harbor freight. This little tool (well, it is NOT so little, as you will soon see in the pics) worked wonderfully up to a point, and then I had some issues that seemed to resolve themselves somehow. I was able to use it on all the rivets on the LE except for the one closest to the outboard tip on both elevators. That last rivet is tool close to the counterbalance skin and ribs to allow it to be used, so you ahve to revert to the hand squeezer for that one. More to come on that topic in a bit.

Here is shot of the right elevator all buttoned up. Came out OK.

I have one episode of a rivet that did not set correctly. I had to drill it out and set another one, and then I noticed something really disturbing about the AD41 ABS pop rivets I was using. Many of them seem to be missing the mandrel on the end, and I can't tell for sure if this is by design or if this is a flawed pop rivet. I am not even sure if the one that failed was one that had the missing mandrel tip or not. Basically what happened is that the mandrel never broke off as expected, and it continued to pull all the way through the hole. Turns out there was a tip on the end but it never broke off. I'll get a pic of that tomorrow.

Anyway - the pneumatic rivet squeezer works pretty slick. In one trigger pull it sucks the rivet stem up, sets the rivet, and deposits the stem in the back of the tool in a nifty little catcher. The action is very smooth and about 99% less violent than when i breaks while using the hand puller.

Here is the manual puller on the left, adn the pneumatic puller on the right.

Since I had a bit of a problem with burs in the holes that I drilled on the right elevator, I decided to take a different approach on the left elevator by using reamers to create the holes for the rivets. The process basically went as follows:

1. Cleco the holes and use duct tape strips in between the clecoes to secure the top and bottom skins together to maintain the hole alignment while the rivets are being set.
2. Ream the holes with a #40 reamer. They are already punched to #41 hole size, so the #40 reamer will work perfectly as a starting point.
3. Drill the holes with a #31 drill bit to prepare the hole for the #30 reamer, which is the final size that is required to fit the pop rivets.
4. Ream the holes with the #30 reamer.

This process left very clean holes with essentially no burs to worry about.
This next pic shows the #30 and #40 reamers, and the #31 drill bit.

Next is a pic of my 12 inch long extended #30 and #40 drill bits. I needed to use both of these for the last hole next to the tip that mentioned earlier, because you also cannot get a drill in there to safely drill out the last hole without risking marring up the counterbalance skin with the chuck on the drill. This method or an angle drill would probably work OK.

Next is the left elevator, inboard section has already been drilled and riveted, and the remaining sections are clecoed and taped as desribed earlier.

Next is the inside of the inboard edge of the right elevator The skins have mated much better than the way the rudder turned out, which I now admit I will most certainly redo, now that I know what I need to do to make the skin form correctly.

And finally a shot of the outboard section on the left elevator. Note the copper cleco for the #30 hole that I have already drilled with the extended length drill bits.

I managed to rivet everything on the left elevator until I got to the last hole. Then I started having problems inserting the stem of the pop rivet into the manual pop rivet gun. I had to stop because I had no way to set the final rivet. What a fitting end to this long drawn out episode of the build. Just seems like it wants to keep scratching and clawing its way against your every move.  I wanted to be livid about this, but instead I guess I was resigned to the fact that this was probably going to happen anyway, just because of the way the elevators have gone thus far. So I stopped and went to a movie to regroup.

I then started looking over the rivet puller. I even disassembled the damn thing trying to figure out why the rivets would not insert into it. I finally found a small sliver of metal that somehow had imbedded itself inside the adjustable head that screws into the rivet puller for the correct size rivet you are using. So it wasn't a problem with the insides of the puller itself - just some junk aluminum that somehow found its way inside the small hole of the insert. It's too late to set the rivet now, so I will finish it up tomorrow. At least I now know what to look for, and I also know a bit more about how the puller is assembled.

Rod end bearings will be next, and then drilling the center bearing hole in the control horns.

451 hours - Rolling the left elevator

A big thank you to my fellow aviator and neighbor Kevin Shepard and his father Bill. Kevin answered my call for assistance to get the left elevator leading edges rolled. His father was visiting and wanted to take a look at my build, so of course I put both of them to work as soon as they arrived. It sure is helpful to have many sets of extra hands during this process.

Only differences between this episode and the one for the right elevator is that I used only 2 sections of overlapped gorilla tape instead of 4 to attach the water pipe to the skin, and I used the 3/4 inch OD pipe for both top and bottom skins instead of the small one for the bottom and the larger one for the top. I did not mean to use the same size pipe on both sides - just slipped my mind. Anyway, I think it worked out fine this time. 2 pieces of tape worked great adn the bends came out just fine. Oh yeah, I also did not roll the edges very far at all. Maybe 35 degrees tops. This worked out very well as the edges of the skins were much closer to where they needed to be by the time I finsihed hand forming the rest of the bends oin each section.

The left elevator is also a bit different than the right in that it is essentially split into 4 sections instead of three. This is due to the slot that is cut in the inboard section to allow for the manual trim tab cable, should one desire to install that trim system. Since I am installing electric trim I will ahve no use for this slot, but that is the way the skins come from the factory. This actually makes bending the leading edges a little easier since it reduces the overall size of one of the sections. That middle section is still a bear to get positioned correctly.

I almost have everything positioned where I want it. I will tweak it a bit more tomorrow before I final drill the holes and set the rivets on both elevators.

This pic shows clecoes installed on all rolled sections"

And I reprimed the bottom skin of the right elevator. Should be able to close that up tomorrow as well. The primer on the left elevator actually did not come off when I removed the tape from the bar and the skin. Must have had enought time to cure hard to the metal or something. So at least I only had to reprime the right elevator.

I am still a bit concerned about the burs from drilling the holes in the right elevator, but I think I knocked them down as best I could.. I think I will use the reamers on the left elevator instead of using the drill bits to see if I can keep those holes a little cleaner. 

A p.S. to the previous post

I forgot to mention in my previous post that I went searching for some information in my blog way back during the rudder final assembly, and I found what I was looking for. I was wondering all this time while finishing up the elevators how I managed to NOT strip away all the primer on the leading edges of the rudder when I rolled those LEs.

The answer: I rolled the bottom or underside edge of the rudder first, and THEN I applied the primer afterward. So the tape never touched the primer. So if I would only have spent the time to carefully research my own previous posts, I would have realized this, and would have avoided having to repeat the steps to reprime the leading edges. Live and learn  I guess.

Somebody asked me if the tape should be able to strip the primer off of the metal like that. My answer: The gorilla duct tape I am using can strip just about anything from anything IMHO, especially from cold aluminum with a primed surface that was stressed during the rolling action. I will be deburring the holes and positioning the LEs so I can reprime them again. I will have to remask the entire elevator just as before and repeat the primer application. Just a minor setback, but a setback nonetheless.