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QUICK BUILD WINGS IIt's a great feeling to move on from the Empennage to the Wings. Even greater when your wings are mostly pre-built - long live Quickbuild kits! The bad news is that Vans do not produce a specific set of instructions for quickbuilders. So I have spent more hours than I would have preferred reading through the slow-build instructions, ticking off all the stages which appear to have been completed, and noting the stages left which I have to complete. In fact the "Wings" instructions (p. 7-1) give a nice summary of the stages that quickbuilders need to complete the wings. No such luck with the Fuselage instructions. Some months ago I bought a precision 1/4" reamer from Avery's, and with the aid of a friend's lathe I reamed out the brass bushes which support both aileron bellcranks. (At the same time I did the bushes for the joystick assembly). The bell cranks fit snugly around these bushes, which is nice. However I cannot complete this process until I prime and install the replacement bell crank bearing support which came with my TS Digiflight II Autopilot Right aileron servo. This needs to replace the normal bell crank bracket in the right wing. It supports the servo which drives the aileron bellcrank when the autopilot is activated. It is chrome-steel and I have decided to prime before installation. 2. Pushrods, flap brace, aileron fairings and aileron support brackets 2.1 Reading the plans - aileron bracket construction and location There is a lot of detail required here, but the instructions are very brief (compared with the empennage). In fact he detail is ALL in the plans and drawings (as it should be). This is where the instructions' "hand-holding" stops. For the aileron attach brackets, it is all on Drawing 10A, parts of which are reproduced below. "Bracket construction" shows the parts which must be riveted together to form each bracket - note explicit rivet call-outs, with countersunk flush rivets required in various places and orientations. The next two images show where the brackets go in relation to the rear spar and reinforcing plates which, in the quickbuild, are already in position, but with empty holes waiting to receive the attachment rivets. The "Rivet call-out legend" is vital as it tells you the required rivet length and diameter, and most important, whether the rivet is round-head or flush/countersunk. These symbols are used to locate the various rivets for the centre and outboard bracket attachments to the aft spar, as shown in the last two drawings. So you need to study the drawings, find the rivet call-outs, and determine for yourself where to countersink and on which surface. Care!
2.2 Preparation, construction, location and attachment (22nd August 2005) I spent 4 hours fabricating wing parts and preparing them for priming. I started with the aileron pushrods (see "measuring pushrods"). Vans supplies lengths of rod which need to be measured and cut to size. The small aileron rods are made from a length of powder-coatd steel. The large ones are 1.25" aluminium tube. I trimmed these by hacksaw and Scotchbrited their surfaces in preparation for Alodine and Primer. I then found the rod end bearing supports and screwed the bearings into these. Two supports were just too fat to fit into the 1.25" pushrod stock, so I used a small flat file to reduce their diameters bit by bit until they slid snugly into place. I marked each rod end and each bearings support accordingly (see "Y" marks on rods and supports below). I then found the aileron bearing support bracket assemblys (W-413 and W-414), and the long pieces of sheet which form flap braces and the aileron gap fairings to fit each wing. With the Scotchbrite wheel I polished the manufacturing artifacts from these items. I used a Scotchbrite pad to finish the outside surfaces of the aluminium pushrods. Finally I clecoed the Flap Support Braces (without flap hinge) and Aileron Gap Fairings in place and match-drilled.
(1st Sept 2005) I spent 5 hours working on the aileron and flap hardware. All aileron and autopilot roll servo pushrods were drilled and deburred, ready to be primed before final construction. I used a wood block with a 45 degree "V" cut into it (see "Drilling aileron control" below) to line up the rods with the drill press. The flap brace has to be COUNTERSUNK (not dimpled) to take the dimpled skin. The set-up is similar to that used in the left elevator trim tab piano-hinge attachment. The hinge is NOT countersunk or dimpled. It lies flat against the flat underside of the flap brace, and is not drilled until the flap position is determined by matching with aileron trailing edge. Just a few pictures below of the pushrods drilled and wing skins dimpled. It takes a lot of time!
(7&8th Sept /2005 ) I had an enormous Alumiprep/Alodine/Priming session yesterday, and today I riveted together the aileron support brackets, riveted these to the rear spars of the wings, and also pop-riveted the flap braces to the inner rear spar. Most rivets can be squeezed, but I found a few needed to be shot, in some cases with the offset Universal Rivet Set. It only took me about 20 minutes to pop-rivet the flap braces in position. I wish all the riveting was this easy! You do not attach the flap piano hinge until the aileron is in position - then you can line up the aileron and flap traiing edges and match-drill to suit. Don't you just love that dish. Imagine me communicating with a geostationary satellite from out here in the bush!
(23rd Sept 2005) Snuck over to the hangar today for 4 hours and finished aileron pushrods (riveted rod end in place). It was easy to keep everything straight for the -12 rivets which fasten rod ends to aileron pushrods. I clamped my squeezer in a vice, enabling both hands free to line up dies so everything squeezed straight and true. I also managed to rivet aileron fairings between rear spars and upper skins, and I began to fiddle with the right wing bellcrank where the Tru-track roll servo mounts. Tru-track supplied lovely drawings but no fasteners! This is a pain because it is clear that AN3 bolts do not quite fit through the mounting holes in the stepper/servo motors. What should I use? I do not want to go "drilling out" these holes without advice from Tru-track and other builders (pictures later). (27th Sept /2005 - 5 hours) Today I attempted to mount the aileron bellcranks and control horn/ bearing assemblies. Disaster struck when, despite being ultra-careful, I managed to strip the upper left platenut which takes a bolt securing the upper aileron bellcrank mount bracket. I do not know how it happened, I was using ultra-low torques, but it just started turning as if there were no thread there at all. I find platenuts a pain because they have a distrorted thread and it is hard to tell whether the resistance to turning is from this, or from the bolt actually mating againat the surface. Anyway it is no big deal, I will have to separate the tank from the wing and reach in to remove then W-731 tie-down bar which mounts this platenut, and replace the platenut. (Note added later - I DO know how this happened: I made the mistake of torquing up the bellcrank pivot nut before installing the mounting brackets - this is easy to do because you MUST have the bellcrank pivot bolt instralled before installing the brackets. The spar flange does not allow you to load the longish bolt once the brackets are in place. Having the pivot bolt tightened meant that the bracket retaining bolts were not exactly aligned with the platenut threads. I think the bolt thread was stripped by the edge of teh bracket hole on the way in.) LESSON: Use this sequence:
(Later
that week..) I
arrived, as usual, to find Millie and Peggy-Sue "on duty".
They are farm dogs but very spoiled. Once at the hangar I installed
the bellcrank and made the tubing spacers which position the aileron
control pushrod rod end bearing. Then I found the powder-coated aileron
control horms and bearings. They come drilled to #30 size, you need
to drill them out to #12 size to take their AN3 bolts - you also need
to carefully drill out the holes in each aileron which take the boldts
which mount these. I did all this, torqued nuts to 30 in.lb and applied
the yellow compound to all torqued nuts.
2.2.2.1 Fixing the platenut problem (5th Jan 2006) - in my new workshop. I am going to have to remove the tank from the wing to get at the tail of a 3/16" bolt and platenut which I managed to strip while attempting to install the right aileron bellcrank. This bolt is one of two which retains the W823 aileron attach bracket to the right spar. The platenut is flush-riveted to the W 731 tie-down bar. To remove the tank I need to unscrew the countersunk screws which attach the tank skin to the wing skins. This was the easy bit. Next I had to unscrew about 20 3/16" bolts which screw into platenuts attached to a series of "Z-brackets" fixed to the spar. To get at these you need to remove the two access plates in the inboard bottom skin. I bought a small battery-powered screwdriver which by chance happens to have the exact torque required to unscrew these bolts. I was able to get it into the restricted spaces and unscrew everything easily. I will apply a drop of Boelube to the threads when everything goes back together.
So here is the wing with the tank removed. It slid apart very easily. Looking through the rib next to the tank you can see the tie-down bar and the offending stripped platenut and bolt tail. Support @ Vans recommend using a 3/16" drill to "drill out" the head of this bolt as one would remove a bad rivet. I intend to anchor the bolt tail with vise grips (padded and anchored well) and use progressively increasing drill sizes to do that. Once the bolt head is off, everything will come out easily and I can replace the platenut. What a pain! Anyway tonight it only took 20 minutes to do this. I first centre-punched the bolt head and used a 1/8" drill to start the hole. then I drilled out the head of the bolt with a 3/16" drill to a depth that looked about right, and used vice grips to prise off the head of the bolt, which was easy. Everything then fell apart and I now have the tie-down bar on the bench, ready to replace the platenut.
17th, 19th, 20th,21st Jan 2006. I spent about 5 hours completing the repair fo the right wing. Here is a plug for Paul McGuire and his company, "Aviation Parts and Equipment". Paul has this retail outfit at Sydney Bankstown airport where he sells tools, hardware, sheet, angle and instruments for aircraft. I faxed him an order for 5 x AN3-6 bolts, 5 x K1000-3 platenuts and 1 oz AN426AD3-7 rivets required to repair the right tie-down bar platenut assembly. It all arrived in TWO DAYS by post for a total cost of AUD$17.00! Thanks Paul!. The white card below with the holes is a very useful gadget he gives out for measuring AN Bolt diameters and lengths, as demonstrated by the two bolts in place. So I reinstalled the tie-down bar, and CAREFULLY re-attached the right fuel tank. One trick I learned from this is that if a platenut does not line-up exactly with a bolt-hole to which it is to be attached, you can insert a tapered punch in a nearby hole/platenut to carefully align everything. This enables you to get the bolt thread started squarely in the platenut, and minimises the possibility of thread-stripping (as happened to me previously). This wing will eventually take the bellcrank assembly, including the modified support bracket which holds the autopilot roll aileron servo motor. This is shown loosly assembled below in pic 2. I will need to order the correct AN3 fasteners before final assembly. One other detail I fixed was to grind down the aileron bell-crank bronze bushes to give the correct clearance between support bracket and bellcrank sleeve of only 1/32" - 1/64". This needs a little explanation: the support brackets (top and bottom) tighten down onto the bronze bush and hold it firmly so it cannot rotate. The bellcrank sleeve rotates around this bush and it must be 1/32" - 1/64" shorter than the bush, allowing it to rotate with a minimum amount of vertical play. I had not identified this detail on the drawing previously, and my default clearances were more like 1/16" - too large and sloppy. So I removed the left bellcrank and ground the bush to provide the appropriate 1/32" clearance (see below). Finally, I replaced the left assembly, leaving everything loose at first when fitting brackets so as to avoid my previous platenut-stripping nightmare as occured in the right wing. I then adjusted the aileron pushrod lengths to spec, and installed the left for completion. The right assembly will need to wait for the correct fasteners to properly install the Autopilot aileron roll servo assembly.
24th Jan 2006 - Today I had a visitor, Steve, who
Now that is amazing. Anyway we talked RV's and flying most of the day and I showed him some of the airstrips and countryside around Manilla. He kindly helped me place my right wing back in it's cradle (thanks Steve). One of the great things about building an aircraft is the people you meet, both personally and over the internet.! (April 2006) I spent most of late March and early April working on basic fuselage stuff - making seats, elevator push rods, and fitting the tailwheel spring support in place. For variety, I also spent a little time fitting the ailerons and flaps to the wings (quick-build pre-fabricated). This was actually fairly easy. First you need to fabricate some tube spacers. I did this with hacksaw and Scotchbrite wheel - I would have preferred a lathe, but beggars can't be choosers. You can see these spacers in the images below. The first image shows the area where the aileron and flap are adjacent. The flap is "attached" to the wing by a simple piano hinge. It is slid into position so that 1. there is 1/4" gap between flap and aileron, and 2. the trailing edges of both flap and ailerone line up (image 1). Images 2-4 show details of the washers and spacers used in the aileron beraing assemblies (large washers missing, bolts/nust not yet tightened). (25th April 2006) John, my SAAA Technical Counsellor, came over today to look over my recent work and to help with the flap installation. My work has been OK except for some servo mount safety wiring which he said was too loose - I will need to re-do this. Anyway we first mounted both ailerons - these provide the reference for lateral and foreward-backward positioning of the flaps. The QB flaps come with one half of the retaining piano hinge riveted in place. We cut some of the hinge provided in the kit to make the mating hinge which needs to be riveted to the upper wing training edge. We then removed three central eyes of the hinge, and inserted two 1/2 hingepins (see below), and drilled two small holes for safety wire to be added later. John preferred not to drill holes in the aileron support assembly (one of the suggested methods). It is critical to get the position of this hinge perfect, otherwise an ugly offset between aileron and flap trailing edges will remind you of the day you stuffed up for the rest of your RV-7 flying career. To do this, John held the left flap in position, with 1/4" gap exactly between inboard aileron and outboard flap, and with both trailing edges perfectly aligned with a straight edge. This is difficult to do, because the lower wing skin does not extend the full length of the flap brace, and it is difficult to get a positive fix. I drilled and clecod a more inboad hole where the wing skin, flap brace and hinge were co-positioned, and we worked from there, holding the flap carefully in position as we worked along the length of the trailing edge. We had a look at the right flap, decided to leave it to another day. The second last pic shows the flap supported by two precision wooden blocks (?) which align everything perfectly, ready for the drill.
(29th April 2006) My Technical Counsellor joined me again and helped with drilling and riveting the right flap hinges. We used small blocks of wood to support the flap at the correct lateral and vertical positions (wings in cradle), and when all looked good, one of us drilled and clecoed carefully, checking alignments as we went. It all went well, and we inserted both hinge pins for both flaps on the inside flap surface (access is cramped) and safety-wired in place. We then had lunch and discussed plans to finish the project. Finally we looked for aileron stops and could not find anything in the instructions or plans. An email to the Australian RV Builders Yahoo List soon brought informative responses, pointing out that aileron stops are actually drawn in DWG 13A. They are solid stops attached to the aileron mounts - movement is "stopped" as the aileron horn hits these stops!! I will install these as time allows. Finally, I spent the evening going through the remaining instructions and drawings listing what still needs to be done. Tasks include major items like Emp attach and finish, Wings Attach and Set Incidence, Panel Wiring, Engine Mount, Canopy and Windscreen fabrication, all Oil and Fuel lines and Wiring - Help! Still, John thinks that with application we could be in the air before Christmas. I hope he is right. (6th August 2006) The manual gives limits for the permitted travel of all control surfaces. Control surface travel limits are set by physical stops. In the case of ailerons, these are formed from pieces of trimmed aluminium angle which is riveted to the aileron hinge supports and which stop movement of the aileron horns on both sides. Mid-range movement is about 28 degrees from the in-line position (25 - 32 degrees). Given that there are no downward movement stops, I assume that setting the correct limits for upward movement on the left side will automatically be right for downward movement on the right side, and vice-versa. Since my flaps are installed, I had very limited access to teh space where the stop needs to go. So I made a narrow slab of wood, and slid it into the space where teh aileron horn will abut against the stop. I drew a line on this wood to mark its position and angle. When I remove the aileron, the wood will indicate exactly where the stop will need to go. That's the theory. More later..
(6th August 2006) Since April I have been working on fuselage and cabin (slowly unfortunately). I have nearly got to the stage where Ineed to trial fit the wings to the fuselage. Before so doing it is necessary to trim the rear spars of both wings as shown in DWG 38 (Image 1 below). This is because these wings are actually for both RV-9 and RV-7, but they need to be trimmed for the -7. I measured THREE times, felt nervous and paranoid (you only get one go per set of wings), and then marked up the bits to be cut off (image 2). Finally i got the courage and used a thin disc on an angle-grinder, working slowly with a litle kerosine as lubricant. The resulting edges were rough, so a file and Scotchbrite wheel was used to smooth to spec. Probably not necessary. but I primed the new metal surfaces. It all seems OK.Phew! Glad that's over!!
(18th August 2006) My TC came over today to show me how to finish the fuel tanks. We also removed the flaps to gain access to the aileron hinge bracket where the aileron stops have to be mounted. The first image shows an aileron stop riveted in plac. The control horn hits this when the aileron reaches 28 degrees up, on both sides. It is impossible to use a direct method to find the position of this stop and its retaining rivet holes. I drew a line on the flap side of the hinge bracket along the direction of the aileron control horn surface, and drilled from that side. The next image shows the fuel level sensor and its float arm, bent to spec. Right and left tanks have slightly different specs so you need to be careful. The thrid image shows JW, my TC showing me how to safety wire the fuel tubing connector inside the tank as per recent directive from Vans. The fourth image is a hi res view of the result. We then mounted the access plates to the tanks using Proseal ("GOOP") to line both surface of the cork gasket. The whit stuff is masking tape used to keep the goop neat.
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