Well, it doesn’t look very nice, but it’s usable. The autopilot knobs are retrofit into the center panel. As outlined on the previous post, I needed to make the cutouts with a dremel tool and then file the rough cuts to accept the modules. Like I said, it looks home made (‘cause it is.)
It’s also getting close to time to paint the panels...
center panel with cutouts and rivet holes.
Center panel with Autopilot knobs
The first place I thought I’d start with the Avionics kit is the very last chapter, 58. This chapter is how to retrofit the autopilot control knobs into the center panel. (Note: the autopilot is typically controlled with soft knobs on the primary display, and this is an optional kit that provides dedicated hard knobs on the panel.)
The majority of the instructions are to help with the retrofit process, but I haven’t gotten anywhere near that stage so this is actually much easier. The picture below shows holes drilled and lines scribed & taped prior to cutting out the panel for the two modules. The yellow tape is going to be the edge of the cuts. The blue tape is “don’t cut here!” since the yellow tape is wider than the slot that will be left between the two cutouts.
Center Panel prior to cut outs.
This is an odd page indeed. It’s an absolutely trivial step of just squeezing 2 rivets to attach the ELT bracket to the bulkhead. What makes it so weird is that the piece that is riveted in is not included with the Finish Kit, but rather is part of the Avionics kit. I am really a bit confused as to why they didn’t just put it in the Finish kit. (Oh, BTW, if you aren’t thinking things through all the way, you may install the fuel tank later in the Finish Kit but before you get your avionics. You’ll need to remove the fuel tank...)
Squeezing these rivets was a moderately nostalgic process since I haven’t done any for a while. Find the rivets. Find the squeezer. Get the dies. Install them in the squeezer. Decided to install them the other way. Eyeball the gap for the squeezed distance. Find the cleco pliers and a cleco. Attach the part. Try to install the 1st rivet. Realize that the punched hole is too small. Find your favorite drill. Find the #30 reamer. Remember that your favorite drill needs a new chuck. Find back up drill and install reamer. Ream 1st hole. Install rivet. Squeeze rivet. Remove cleco. Ream 2nd hole. Install rivet. Squeeze rivet. Find acceptance tool. Verify shop heads are acceptable. Put away tools. Take picture. Sign off page in The Book.
ELT Attach Bracket
Whoops! This is a late entry. I just noticed that I hadn’t signed off on this page although I completed it some time ago. For the record, please be advised that the control sticks have been installed.
Close up of R control stick
Control Sticks
On Dec 3rd, my final crate arrived with the entire avionics kit and firewall forward kit. I didn’t have much time to do anything with it, as my daughter and her family had just arrived from Louisiana to visit. Nonetheless, I managed to snap a few pics as it arrived, and then as I took it apart a little bit. At the time of this posting, I haven’t done any inventory of the parts. That will have to wait for a few weeks (work schedule from hell, plus the sad trip to Phoenix for the funeral of my nephew). Speaking of waiting for weeks, I have done some work on the control systems in the last two weeks, but no pages were completed, thus no documentation.
Engine & Avionics crate
Engine crate
It’s like a матрёшка doll—open it and find another inside! This is the engine crate.
Engine, ready to be unwrapped
Unwrapped Engine, top view
Unwrapped Engine, side view
I’m probably not going to work on this for a while. It was challenging to get it out of the double crate, and I want to be able to have some mobility until I hang it on the plane. Nick (Big Nick, fiancé to my daughter, Melena) helped with the labor & lifting. To gain the mobility, I turned the small crate over and used a big drill and a jig saw to cut out the base of the crate that held the tapped lugs and just rebolted the engine to the crate floor after quickly attaching some wheels. (The wheels were scavenged off of the no-longer-needed frame that I use to build up the fuselage.) The engine is now wrapped in a sheet and resting quietly beneath the fuselage until I can get back to work on it.
Big Nick
Addendum 12/18/14
I finished unpacking everything and getting it all inventoried. The only things that I was missing in the kits was the documentation re: the contents of 5 bags. I got those by email and did my last check only to find that I’m missing just one piece: ”Al Bushing 0.197 x 0.313 x 0.968" . The other “gotcha” was that they sent me a European transponder. I actually got a phone call from Daryl who apprised me of the problem before I even opened up the boxes. He said I could use their UPS shipper number, but the local UPS store said I’d have to drive to the main office an hour away. I sent it FedEx instead.
Well, I spent more time looking for the parts than I did actually using them. For some reason, automotive brake lines are filled using a vacuum to pull fluid through the system, while The Book specifically states to force fluid from the calipers up into the brake reservoir. It took a bit of searching to find the basic tools seen below. Once I got the hang of it, it was pretty straightforward.
The only bummer is that there’s a leak at the brake line-to-caliper fitting on the left side, so I’ll have to drain that side and remove/replace the AN823-4D. C’est la vie.
Brake Fluid filling kit
Addendum 12/18/14
There was a leak at the L fitting between the brake assembly and the Al line down the leg. I finally got around to removing and re-installing the fitting. I’m slightly concerned about the brake fluid that leaked onto the brake pads, so those will be very carefully watched when I get around to taxi tests.
No page number associated with this page, just a happy smile. I received the seats & carpet kits several weeks ago, but today was the first day that I had a real urge to unwrap them and take a good look. They’re certainly not needed at this point, but it was a nice way to spend 30 minutes. I’m planning on installing a bit more hardware for the rudder cables and elevator cables, then routing the cables to the baggage bay. After that, I’ll lay in the covers for the floors and tunnel to keep out any loose objects (Foreign Objects, in both medical and military parlance). Those will just be held in with one or two screws, and left in blue until their final installation.
Seats
One of the simpler jobs complicated only by the fact that you have to disassemble things to get to it. In this case, I needed to remove the torque transfer arms (visible as the brighter white in the photos) in order to finish drilling them for the bolts. Got them out, drilled everything, put them back in, installed the new Torque Tubes. Not bad at all. It gave me a pleasant morning in a chill, but workable garage to just be one with the building process.
Torque Arm bolted to Torque Tube
Torque Tube outside of skin
Wheee! This was a fun day, as I got to install the wings and look at my beautiful bird coming together! I had the assistance of Nick and Nick (son & son-in-law). The whole point of the day was to get the fuselage out of the garage, attach the wings, line up the two components of the torque tubes and match drill 2 holes on each side. Like many things, the day was full of challenges that made it fun. As you can see in the pictures, it was a cold day—about 20 °F. (BTW, yesterday, it only took my frozen fingers about 2 hours to remove the gas tank fitting so I could have access to the R torque tubes.) I worked 3rd shift last night and woke at 3:00 this afternoon to get this done before it got dark and (too) cold around 5:00 or so. Advice: if you are in a hurry, stop and reschedule so you aren’t in a hurry.
Big Nick was granted a few hours of ‘guy time’ by his fiancé and helped me out. First thing we did was scrounge in the garage to find some 1/8” shims to put a measured amount of droop in the flappers. (Discussion on VAF about how the wing was designed for the flapperons to be neutral in flight, but wind loads force them up just a tad into a reflexed position, so The Book has you install them with 1/8” droop to allow the wind loads to put them in neutral in flight.) Then we chiseled and shoveled layers of sheet ice off of the driveway so we weren’t guaranteed to slip and fall. I maneuvered the plane out and into the driveway, then Big Nick & I maneuvered the wings into the plane while Nick guided the flaperon activation tab into the appropriate slots of the torque tubes.
I then noticed The Book calls for a 0.063” shim to be placed between the inner and outer torque tubes. Argh! I really should stop working and sleeping so I can do a better job of reading ahead. A few moment of rummaging around in the garage revealed that the hinge material was very nicely dimensioned to be the long strip of 0.063” shim. A quick pass with the bandsaw to remove the eyelets and we were ready to go.
I didn’t even take any pictures of the actual drilling of the torque tubes. This photos on this page are really all about the fact that I got to see the wings and the gear on the fuselage. (All it needs is a tail section, the canopy, an engine with prop & cowling. Sigh....)
Aft view of 012 with wings and wheels, in the driveway
3/4 frontal view
My beautiful bride snapped this from the front door. You can see the main gear still has some camber, and the nose wheel looks way to far forward without the engine. The turtleneck is still sheathed in blue, as it’s only held with cleco’s and no rivets. From here, the wings good perfectly smooth and ready to lift! (The roses didn’t do so well in the snow fall, however.)
It’s a bit fuzzy but, you can see two holes on the edge of the riveted skin; the one on the left is open, the right has a 3/8” metal plug installed. These are the holes that weren’t there. I did a bit of research and memory dredging and recalled that there was a Service Bulletin about re-checking the torques on the landing gear bolts due to some cracks. The inboard bolts can be access through the access holes in the belly, but the outboard bolts aren’t accessible. The SB says to drill some 3/8” holes. The holes are too small to get a socket through, but you can pass a socket wrench extension through them, attach the socket via the access holes and thence proceed to check or re-torque the outboard bolts. Pretty simple, eh?
Whenever you see that something is “pretty simple” you know that there’s going to be a catch. in this case, it was finding the darn metal plugs. my usual technique of ordering directly from Van’s didn’t work, as the part doesn’t appear to exist on their master order form. I’ve had this happen a couple of times in the past, as their system is a static parts list of what they sell—it’s not a live database of everything they actually have. OK, on to Home Depot. A quick computer search verified that these were items that they had listed and actually had in stock. They lied. Turns out that the local Home Depot store was in the process of doing inventory in that isle, so they’ll probably figure out that that little drawer was empty. OK, on the next not-quite-local Home Depot. Better; they had 3 (but not 4) of these 3/8” plugs. While I was there, I grabbed a 3/4” plug for the hole that is under the mixer’s main bolt & cotter pin. Last stop: Lowe’s for the 4th small plug. After that, it was pretty simple.
I Access Holes for SB 12-09-26
Here’s the final page of the brake line installation. I was also able to install the final baggage corner skins as well as the brake cover plates. I’m planning on drilling the flaperon torque tubes later this week, so the corner skins have to go on now. The Book calls for them to be installed after the tail cone goes on, but I’ve been shown that it’s possible to get the overlaps correct even if I go out of sequence. (I think standing on a stable surface and looking right at the torque tubes will be much better than trying to crawl into a completed airframe and drilling at a weird angle.)
The brake caliper lines were placed on the trailing edges of the main gear legs last page: this page just tweaked their placement and secured the anti-abrasion sleeves that I had previously installed.
The only step that wasn’t completed was #4, which calls for installing some sheet metal plugs in the access holes on the bottom of the fuselage. Just two problems—I didn’t receive any sheet metal plugs and there aren’t any access holes! Stay tuned...
Brake Caliper Lines tie wrapped in place
Only a little bit of trepidation with this page. For some reason, I’m just not comfortable working with tubing. I managed to ruin one segment when I put too much of a bend on it without realizing that the collar had migrated proximal to the bend. No matter what I tried to straighten out the segment, I couldn’t get the collar back into position. I was quite pleasantly surprised to find that I had sufficient AT0-032x0.25 to make another caliper brake line. It’s almost like the folks in Oregon kind of expected that not all of us would get it right on the first time!
I also took the liberty of sliding the protective clear tubing over the brake lines on this page, rather than slitting them and placing them over the finished brake lines after they were installed (as called out on the next page.)
Brake Lines at Inboard Gear Attach Bracket
I didn’t realize it when I took this picture, but it’s a pretty good match for the detail view drawn out on page 35-05. We are looking straight up (through an access plate) into the bottom of the main channel. The wedge shaped structure on the bottom is the tapered main gear leg. You can see the AN4 and AN6 nuts holding things together. On the upper side of the Inboard Main Gear Attach Bracket you can see the main brake line terminating in a brass fitting; on the lower side is the just-installed caliper brake line terminated with the blue anodized AN hardware.
Caliper Brake Line looping around Main Gear Leg
I really like this picture. I managed to substantially dim the flash with my fat finger, but the effect was excellent for highlighting the key point in image. I’m also really surprised that I was able to make this structure at all, much less make it look nice & professional.
My timing worked out perfectly in this case. Once I committed to putting the plane on its gear, I would no longer have the convenience of the mobile platform I built with the castoring wheels, thus mobility in the garage would be a bit of a challenge. I ordered the tow bar / parking brake kit last week, and it arrived the day I finished the nose gear.
As part of the ‘build-ahead’ motivation described earlier, I elected to do some fairing pre-work on the nose gear fork prior to installing it. (The instructions in section 36 require removing not only the tire/wheel, but also the nose fork, so I did some work prior to its installation.) It turns out that I would have had to remove the fork in order to insert the bolts & washers that the tow handle uses, so that was already done.)
Page 52-03 describes how to measure & modify the handle so that it can be used as an ersatz parking brake. It’s quite ingenious, really. The handle is used to put pressure on the brake pedals and is then wedged into the structure beneath the seat. In order to make the proper measurements and drill, I have to have the brake system completed and filled with fluid, so that page will be deferred. For now, I have a proper way of maneuvering the plane in/out & around the garage.
Tow Bar
Major Milestone! The airplane is now standing on it’s own 3 wheels! This was a pretty easy page, with nuts & bolts and tapping and wrenching, but nothing magic. I was a touch concerned at first that upon dry fitting, the upper portion of the nose gear weldment didn’t match up to the engine mounting brackets. Needless to say, when you tighten up 13 bolts and have the plane resting on the gear instead of the gear hanging down, things matched up nicely.
Nose Gear Assembly
Standing on her own!
positive camber on main gear
Like the concern that things weren’t aligning properly with the nose gear weldment, my eye doesn’t like the amount of camber that I see here on the main gear. On the other hand, the plane isn’t finished and is severely underweight. I expect that there will be a much lower camber value when it’s completely assembled and loaded with pilots & fuel.
Figuring out how to install the brakes was a moderate challenge. On two occasions I started taking apart things that Shouldn’t Be Taken Apart, but I didn’t do any damage. It was pretty straight forward after I got through the mental imagery of what attached to where.
front view of L Main Gear
aft view of R Main Gear w/ Brake
In this aft view, you can see the fitting for the brake line and the shoes on the rear aspect of the disk. You can also see the re-attached fairing support and clearly see why it had to be removed in order to put on the brakes. Live & learn. (If I ever build another RV-12, it’ll be a lot easier to spot the redundant assemble-disassemble-reassemble sequences.)
As mentioned in the previous post, I do try to read forward in The Book to identify places where I can avoid re-work. Here’s an example of getting some of it. I had read that it’s a good idea to install a bracket for the gear fairings when installing the main gear, as you have to remove the tire. It turns out that you have to remove the entire axle as well. Here’s the axle with an adaptor bracket on the inside edge of the gear. That, in turn, supports a mounting bracket that will be used to support the fairings. I installed it because it allowed me to check off this page as complete. I was very proud of the fact that I got the adaptor bracket in place before I mounted the tire. On the other hand, I promptly had to remove the fairing bracket to install the brakes... Like I said, I got to avoid some of the rework...
I actually got a lot done in 2 working days. Probably one of the more physically demanding tasks was accomplished with the help of my son, Nick. I thought I’d need the assistance of my future son-in-law, Nick, but Nick stepped up to the plate and did a great job of manipulating nuts, bolts and washers on the top of the main structure while I worked underneath and supported the gear legs and played with my own collection of nuts & bolts (not to mention the greased retaining plates!)
After we got both gear legs attached and snugged, I decided to do a bit extra. The gear retaining hardware and wear plates were greased as per The Book. I noted that most of the bolts had grease on them by the time they were laboriously fit through all of the hardware and I just have a bad feeling about putting lubricants on devices that are designed to hold together by friction. Much to Nick’s dismay, we removed each & every nut & bolt (except for the AN6’s that were recalcitrant) and cleaned off all of the grease with some isopropyl alcohol. (The AN6’s were cleaned in situ.)
I then had the opportunity to use my brand new “big” torque wrench. The one that was recommended for the kit was not capable of reaching the specified torques for the AN6 hardware. I made an estimate of the prevailing torque for the nuts, for the rotation of the bolt and ended up using a final torque of 20 ft-lbs.
Main Gear Leg
Attachments of Main Gear Legs
A sharp eye may have noticed that the axles are already installed on the main gear legs, which isn’t actually called out for until the next page. I tried to read pages coming up and stay ahead of the book, so to speak. I was moderately successful in this case. I elected to install the main axles and do the toe-in/toe-out check prior to torquing the main gear attachments. My intention was that if there was a slight mis-alignment, there may be some room to “settle” things before tightening up. Much to my surprise, the axles are well aligned and do not require any “settling” or any shims to be added! (I even looked at pre-purchasing a 1° and 0.5° shim just to have in my shop because I hate getting close to finishing a page, only to have to defer. I discovered that the shims are about $20-30 each! Not going to buy ‘em unless I need ‘em!)
The picture of the attachments shows the lacquer I use to visually assure myself that I used a torque wrench to set things. The other nut is not visible due to the wiring conduit. That had to be removed and replaced in order to finish this page.
PS: Bob just sent me the link for AC43-13-1B.“View fuselage assembly. Project coming along very well. Discussed proper method of installing cotter pins. Discussed future installation of avionics and engine. Already performed some fuel flow testing."
This page took a couple of days, but it was fun because I was working in a new domain. Steps 1 & 2 were straight forward: drill 3/8” into the firewall and engine mounts and attach the engine standoff. On the other hand, drilling though stainless steel and then steel was not easy. Rather make the jump from 1/4” to 3/8” in one pass, I staged up the drilling in 3 steps.
Engine Mount Standoff
With the engine standoff taken care of, I turned my attention to the tires & wheels. Never worked on these before. Learned quite a bit! Specifically, I learned that it’s really easy to get the “front” and “back” confused. I admit to reassembling and disassembling the 1st wheel several times. I actually re-assembled it a bit farther than I was supposed to. i’ll have to take the brake off again when I put it on the plane. On the other hand, I had watched Walt Erdy, my mechanic for the Cardinal, change a tire so I had previously seen how to use the talc powder, etc. I was pretty pleased with my progress of assembling the front and both main wheels.
Main Wheel, outside face
Main Wheel, inside face, with brake
Inboard Main Gear Attach Braces
Again, not a big deal, and thus a highly satisfying page.
Flap Handle with Actuator Button
Flaperon Torque Tubes with Spacers
The torque tubes needed to have nylon spacers epoxied in place. I don’t understand why they have to be #12 drilled where the rivets go, especially since the rivets don’t attach anything. Weird. The black and silver gadgets that you see sticking out are allen wrenches that happen to be 1/8” wide. They are holding pressure on the nylon spacers until the epoxy sets.
BTW, I’m done with this chapter for now. The next step involves attaching the wings and drilling the matching torque tubes. Those require the final skins to go on the belly/lateral edge of the fuselage and those require the tail cone to be attached. On the other hand, it would be much easier to do the match drilling without having to climb into the back of the fuselage when it’s attached. Oh, well. I’ll solve that dilemma when I get there. For now, I can’t do anything with the rudder or stabilator control links since they aren’t anywhere near the fuselage itself. In other words, I’m on to the gear!
Not much fuss. It was nice to have some basic metal work, without the complications of cramped small spaces. It felt fun to realize that I had gone from being afraid of squeezing rivets to discovering that they were therapeutic.
Flap Handle Detent Bracket Assembly
Not pictured: Flap Handle actuator assembly
The flaperon pushrods were fairly easy to build. It took quite a bit of percussive coercion to install the studded end-caps into the pushrods! I don’t believe that the rivets added anything to the strength or stability of the assembly because those guys aren’t coming out on their own. Attaching the pushrods to the mixer was easy. Attaching the flaperon torque tubes was a bit trickier because of the traditional problem of putting the inside washers into place when you are working with a small, enclosed space. To make matters worse, the fuel tank is still installed on the R side and I wasn’t able to remove it because the fuselage is too close to the floor to get under it to remove the fittings. Perseverance is key, and I was eventually able to get everything bolted (and washered) in place.
Flaperon Pushrods attached to Flaperon Torque Tubes
Flaperon Pushrods attached to Mixer
What a royal pain in the pa-tootie! It took forever to get this page completed. The two biggies were my work schedule (lots of unwanted overtime) and the fact that it was not possible for me to fit the ends of the control rod assembly into the forks of the control sticks. I had the fuselage up on its R side and was working in relative comfort. Unfortunately, I couldn’t see up into the L seat area because my trifocals have the close vision lenses on the bottom and I can’t crane my neck that high up any more. I couldn’t see down into the R seat area because..., well, I can’t remember what was in the way, but it was.
The end of the control rods require two steel washers to be interposed in-between the forks of the control sticks. Try as I might, it wasn’t possible to fit them in. To make matters worse, at one time I dropped the pushrod assembly from the L side (upper) and it fell all the way through to the R fuselage wall. In the process, one of the steel washers disappeared and I spent over a week searching for it. I had reluctantly concluded that it may have been flung free of the aircraft into the garage. Luckily, I found it when working on the wiring harness re-work, so I no longer have to worry about a loose foreign body floating around in the belly of the beast.
Others on VAF confirmed that this is a problem. One gentleman said that he had to jury rig a spreading apparatus to open up the forks a bit. Another guy was able to remove the control sticks, attach the rods and somehow snake the contraptions into place. I did end up removing the control sticks (and having to rewire the PTT harnesses in the process) and finally got the damn steel washers in place. I didn’t have to make a Rube Goldberg spreader, but I did use a pair of pliers as spreaders to get the washers in place. I wasn’t able to snake the stick and rod assembly into the proper place, and even got it stuck to the point that I couldn’t get it back out for half an hour.
I finally elected to unscrew the control push rode from the bearing on the end, re-install the control stick and then re-thread the rod onto the bearing. To keep the length “just right” I used superglue on the AN316 jam nut to keep it in place. After I got everything installed, the sticks weren’t quite parallel. I locked the mixer in neutral (see pg 32-09) and noted that the R stick was a little too far to the right while the L stick was vertical. I disconnected the R pushrod from the mixer, backed out the bearing stud by 1 revolution and that brought the stick to vertical nicely.
Last, but not least, I found that the control pushrods rub against the AN365 lock nuts holding down the front control block. They only make contact with the stick full back and full roll (either direction.) I’m waiting for some low-profile lock nuts to replace the ones currently in the kit. If that doesn’t fix the interference, I’ll grow more grey hair and figure out something. I’ll also post a query to VAF to make sure that I didn’t do something wrong.
Control Stick Push Rods attached to Mixer
Push Rod connected to fork at bottom of Control Stick
Push Rod rubbing against lock nut
---------------------
Addendum: I discovered why the push rod was too far forward and rubbing against the lock nuts. I’m not yet used to the way this plane flies, and made an error with the use of the flap control rod. I had pushed the flap control rod all the way down, past the detent for 0° flaps. This would make flaps slightly reflexed (e.g., negative flap angle) and is not an approved flight configuration, thus the designer had no need to verify that the internal parts would not contact each other. When the flap handle is pulled up slightly, it pulls the push rods aft just enough to not contact the lock nuts (and makes highly loud “thunk” in the process!)
Flap Handle Blocks
Here’s the “rest of the story” (to quote the late Paul Harvey) from an earlier mistake. (see the entry for 4/30/14.) I had placed some nut plates on the wrong side of the medial seat ribs. I was able to (eventually!) drill out the rivets and place the nut plates on the correct side using the lightening holes for access and the -3 pull rivets instead of the AN426-3’s originally called out. The only thing I couldn’t do was remove/reverse the dimple for the rivets, so the new rivets were not only not countersunk, but they actually are about .010” proud of the surface. Today was the day that I had to deal with that discrepancy.
To my great relief, I deduced that the pieces that were going to go against those surfaces were the nylon retention/pivot blocks for the flap handle assembly. Nylon is a much more forgiving material than steel or even aluminum! I did have to grind the short (pivoting) tube of the flap handle to get the handle assembly (handle and two nylon blocks) to fit in between the seat ribs, but it’s a nice tight fit and has no slop or wobble. I did have to swear a bit to get the nylon block to get over the lip of the elevated rivet, but once that was accomplished it went easily from there.
The Book calls for me to able to put a piece of paper between the pivoting tube and the fuel line. It cryptically states that it’s allowable “bend the fuel line slightly.” VAF made an old cryptic reference to a wooden tool, but the link was dead so I don’t know what kind of tool they were discussing. No matter—I had been given the clue I needed. I drilled a 5/8” hole in a piece of plywood and then cut right through the hole. That then went over the fuel line and was gently wrapped with a dead-blow hammer to put a slight bend in the fuel line to allow it to clear the flap handle. The above picture shows the paper slid between the fuel line and the tube to demonstrate no interference. You can also see the business end of the wooden tool described above.
Flap Pushrod and Mixer
No drama here. The (correctly oriented) mixer arms accepted the mixer bell crank and flap pushrod without any difficulty. Note the drop of orange lacquer denoting a torque wrench was used to correctly set the final torque. (In other words, that I hope to never disassemble this again! :-)
Remember a couple of pages ago when I asked if you saw anything funny about the flaperon mixer arm? Here’s that picture for you to take a look at.
Flapper Mixer Arm (original)
Note the nut plate on the far end. We are looking down at the mixer arm and the nut plate is visible on the upper surface. On the next page, I’m supposed to put a bolt through the upper arm and into the nut plate on the lower arm. That means that we are looking at an upside down mixer arm. This is the kind of thing that gives me nightmares about this project. Here’s a classic example of something that I built incorrectly and is nearly impossible to fix due to multiple overlying / subsequent structures. It took about half an hour of fiddling before I concluded that there was no way to disassemble and remove the mixer arm intact.
Mixer Arm, removed in pieces
It was ugly, but I managed to get the thing out by hacking each arm into two pieces. I have a dremel tool with a flexible extension. I used a cutting disk and a lot of patience to make a very oblique cut through each arm. (Next time I’ll hook up the vacuum hose right next to the work and collect the dust and debris as it is made.)
New Mixer Arm
Here’s the new mixer arm, properly installed. It actually wasn’t too difficult to slide the pieces into place, but lining up the washers and the work pieces required the assistance of my son working from the underside of the plane and gingerly pushing the bolt forward as I held things in place. To add insult to injury, we finally got the bolt in place only to discover I had used an AN4-21A instead of the AN4-21, so we had to re-install it again. Oh, well. It’s finally in place. I did take advantage of my situation. When I had the original piece in (upside down) I noted that it rubbed against the thin shim overlying the electrical wiring. I took the new lower mixer arm and buffed the edge that is close to the shim to give it about 0.010” clearance. nice!
