SDSEFI flywheel modification [4.5 hours]

In order to use SDS EFI &/or ignition products, it is necessary to modify the ring gear to insert magnets for timing sense. This is a straightforward procedure, but not commonly done for dual pulley ring gear as used when an A/C compressor is fitted to the engine.

My ring gear (flywheel) was supplied by Airflow Systems as part of the A/C kit, and uses a serpentine belt for the A/C compressor drive. The magnet insertion points wind up in the middle of the serpentine belt area, which changes how things need to be done compared with the standard procedure published by SDS. Here’s what I did.

My flywheel had timing marks on the front side only. This confused me for a long time because the timing marks didn’t line up with the tooling holes as described in the SDS procedure. It turns out this was all because of my ignorance about Lycoming engines. When timing marks are on the front side of the flywheel, the TDC #1 mark lines up with the small hole at about the 2 o’clock position (viewed from the front) of the starter motor. When timing marks are on the aft side of the flywheel, the TDC #1 mark lines up with the vertical split at the top of the casing. So, with the flywheel lined up at TDC #1 (which I confirmed by looking at the #1 piston through the top plug hole), I marked the rear TDC #1 mark, and the tooling holes then matched up as described in the SDS instructions.

There is a difference though – the tooling holes in the Airflow Systems flywheel are 3/16″, whereas those in the standard flywheel are 1/4″. Ross at SDS kindly made me a drilling jig to suite the flywheel I have.

I then went ahead and drilled the flywheel exactly as per the SDS instructions, using a new #29 cobalt split point drill and plenty of cutting fluid. By sheer good luck, the holes wind up exactly centered in one of the grooves for the serpentine belt – see the pictures. This is lucky because it means it isn’t necessary to rebuild the “crest” of the grooves on the flywheel, just fill in material that has been removed inside the groove.

I tapped the holes #8-32, again as per the standard instructions, and carefully de-burred the sides of the holes in the micro-V groove using needle files, sandpaper and a magnifier. I then cleaned out the holes thoroughly with acetone. At this point though, it is necessary to deviate from the SDS procedure.

There isn’t enough depth to insert two grub screws as well as the magnet, only one grub screw will fit. Here’s what I did:

  1. Each hole contains the magnet, and one grub screw. I soaked the grub screws in acetone to remove any grease or oil, then set the four grub screws aside on a clean, dry tray.
  2. For each hole, I picked up a grub screw with an Allen key, applied red loctite (these aren’t ever coming out) to the grub screw threads, and inserted the grub screw to a bit short of the right position from the outside, leaving the Allen key still in place.
  3. I then mixed up some 5 minute epoxy, filled the hole per the standard instructions (the plastic shaft of a Q-tip with the head cut off works well for this), and inserted the magnet from the inside. The magnet gets pulled in and smacks against the grub screw.
  4. Now carefully wind the grub screw further in, until the magnet is at the desired position, just inside the inner surface of the flywheel. Remove the Allen key. Wipe off the excess epoxy with some acetone on a clean rag.
  5. Clean off the red loctite from the serpentine pulley groove with acetone. I used a piece of paper towel with acetone, and a clean feeler gauge to get right down to the bottom of the groove. Then I used a Q-tip dipped in Acetone to get down and clean the loctite out of the threads in the hole, above the grub screw, while holding the flywheel so that the acetone would run out of the hole rather than down around the grub screw – so as not to displace any loctite around the threads.
  6. Do one hole at a time – go back and repeat steps 2-5 another three times, making sure to get the magnet orientation right. Then set everything aside for a few hours or overnight for the epoxy and loctite to cure.

Now it is necessary to “rebuild” the damaged groove. I used a product called Devcon Titanium Putty to do this. It’s an expensive product and you only need a small amount, I was able to borrow some from a friend that is a commercial user. There are other metal repair products around that would also be suitable.

Mix a small amount and force it down each hole so that there is a continuous layer of putty around the top of the grub screw out to the bottom of the groove, and use a fine knife to roughly shape the two sides of the groove, ensuring the threaded hole is fully filled up to the top of each side of the groove. I then let the Titanium putty cure for 3 hours. Don’t let it go much longer – after about 6 hours it gets a lot harder to work.

Three hours after applying, I used a combination of tiny needle files and various fine grades of sandpaper to rebuild the groove in each of the four hole positions. I started with the files, then switched to 120 grit paper to get each position nearly done. I wore a magnifying headset to do this, so that I had good vision for this micro-surgery. When I got close to the final result, I set the flywheel aside for another few hours for the putty to harden a bit more.

After about five hours total, I did some further sanding using 240, 400 and finally 800 grit paper to polish each side and the rim of the groove to complete the rebuild. The Titanium putty is well secured by the threads of each hole – see the final picture. The job is done when each side of the groove is smooth and flat, and you can run your fingers across the top of the groove with your eyes closed and not be able to tell when you run across where the hole was.

  • f50a
    f50a
    #29 hole drilled in Airflow Systems dual ring gear
  • f50b
    f50b
    Hole tapped 8-32, not yet de-burred
  • f50c
    f50c
    Mixing Devcon Titanium Putty
  • f50d
    f50d
    Titanium putty applied
  • f50e
    f50e
    After filing and sanding Titanium putty

 

Showplanes cowl ctd. [23.0 hours]

With the two outer cowl halves fitted, the next step is to fit the bottom cowl center support structure. This comes in two halves, that have to be trimmed to fit around the front gear leg/fairing. A long time ago I fitted nutplates to the bottom fuselage to hold the rear fairing, so it was fairly straightforward to make the slots necessary to allow the two halves to fit around the gear leg.

Then you fit the lower cowl, and match drill the support structure with the lower cowl. I am fitting eight skybolts, four each side of the gearleg, to fasten the lower cowl to this center support. I found that the support extended into the honeycomb’ed area of the lower cowl, which is no good since it is supposed to be flush against the solid part of the cowl, so I trimmed the nose of the structure and will close it in with a layup after I fit all of the skybolts. With that front section temporarily open, people now mistake it for some sort of air scoop!

Next I started on the intake plenums, which come as a kit from Showplanes. The lower third of each intake hole is used for induction air. Each intake plenum channels induction air down to a center combining section, which supports an air filter each side with drain holes for water, and mounts on the throttle body.

The right hand intake plenum actually intersects with the #1 cylinder head and #1 exhaust pipe, so it is necessary to trim the plenum and do layups to provide the necessary clearance. First though, the two intake plenums need to be trimmed and fitted to match the lower cowl intakes. The VAN’s front baffle ramps need to be cut out and new ones made to suit the Showplanes cowl. The support angles in front of #1 and #2 cylinders are used as a reference for locating the intake plenums, by means of a temporary metal bracket, clamping the plenums into place while epoxy’ing fiberglass supports in place.

I purchased this intake kit before Showplanes made one available for the SDS 80mm throttle body, so my center section had a 3.5″ hole in it. Once the intake positions were set up, I had to extend and reduce the throttle body connection to match. I protected the throttle body with masking tape, and coated the inlet connection point inside and out with PVA release. Then I used a balloon to bridge between the throttle and existing moulding, with everything supported in place, and wrapped several layers of fiberglass cloth to make the adapter cylinder. Once cured, I was able to pull the assembly straight off the throttle body and clean everything up. I decided I needed a bit more extension so I scuffed the outside surface, used packing tape around the throttle body, set it up vertically with the center moulding on the bottom, and applied another two layers of fiberglass. After this cured, I was able to make a nice straight cut in the end and a hose clamp applied enough pressure to the moulding to hold it securely onto the throttle body.

Next I finalized the cuts around #1 cylinder head, packed around the head to establish the required gap, and applied packing tape. I fiddled with the alignment of the entire assembly and decided I wanted to change the direction this plenum took so that I don’t have to modify the assembly to clear the alternator. So I cut around almost the entire section as well. With a balloon in place, I applied fiberglass cloth around the plenum cuts (allowing enough excess to be stretched into place), and carefully “smooshed” the plenum in place, which pushed the balloon inwards in the necessary places while establishing a smooth transition between the original shape and the modified sections.

Next job is to do the same around the #1 exhaust pipe. After that, I need to modify the left hand inlet plenum because of the A/C compressor, but that’s another story.

  • f49a
    f49a
    Center fairing protrudes too far
  • f49b
    f49b
    Trim line Showplanes front center fairing
  • f49c
    f49c
    Trimmed Showplanes front center fairing
  • f49d
    f49d
    Showplanes center fairings
  • f49e
    f49e
    Positioning Showplanes intake plenums
  • f49f
    f49f
    Positioning Showplanes intake plenums
  • f49g
    f49g
    Positioning Showplanes intake plenums
  • f49h
    f49h
    Essential equipment for fiberglass work
  • f49i
    f49i
    Setting up to extend intake plenum around throttle body
  • f49j
    f49j
    Completed intake section extension/reduction
  • f49k
    f49k
    Modifying right intake plenum
  • f49l
    f49l
    Ready for layup
  • f49m
    f49m
    Ready for layup
  • f49n
    f49n
    Right intake plenum layup
  • f49o
    f49o
    Right intake plenum layup to clear #1 cylinder head

 

Showplanes cowl – initial fit [48.0 hours]

Very slow progress recently due to various issues, travel and otherwise. I’m also way behind with build log posts, so here’s the first catch-up one.

I started looking at the engine baffles, and fitted some of the rear ones. I can’t trim the baffles until I fit the cowling. I can’t fit the cowling without knowing where the spinner is located, and I can’t figure that out without mounting the propeller. So, out of the farm shed came the propeller crate, and I unpacked and fitted the Hartzell 3-blade composite propeller. Then I was able to bolt the spinner in place, and measure the distance from the flywheel to the spinner.

Just about every builder seems to make up a simulated spinner from a circular piece of wood, as described by VAN’s. I didn’t have any bolts on hand that would suit such a thing, and it seemed to me the real spinner hub was already a pretty good reference for setting up the cowl. So that’s what I did, and it worked out great. There is of course the issue of also having the real composite propeller blades in harm’s way during the cowl fitting process. This is just a workshop discipline issue as far as I’m concerned, and simply means being clean and methodical – so maybe it actually helps.

The Showplanes cowl itself is a work of art – a very high quality moulding and the fit to the fuselage is excellent. The instructions that come from Showplanes, though, are quite poorly written. For the initial cowl fitting the message is to simply follow the VAN’s instructions from the RV-10 build manual. That’s what I did, and if I was going to do it over, I would do the top cowl aft edge final fit differently, as I’ll note below.

Here then is the complete procedure I used to fit the cowl. With this procedure, I found that I only had to get the bottom cowl in position once, i.e. trimming of both the aft and side edges were done in-place, so by the time I removed the bottom cowl for the first time, it was fitted with all four side and rear hinges riveted in place.

  1. Trim the front flange of the upper cowl, so that the two cowl halves fit together with a circular front surface that is a good fit with the spinner. I drilled six #30 holes at the positions recommended in the Showplanes instructions, so that I can easily fit the two halves together in the same position with cleco’s. Don’t drill out for nutplates yet.
  2. Run a piece of 2″ masking tape across the top of the fuselage, with trim lines at 3″ and 4″ back from the edge of the fuselage where the top cowl aft edge will need to be trimmed. After marking these trim lines, I also ran a piece of 3/4″ masking tape around the top of the fuselage, about 1mm back from front edge. This was simply to protect the top skin when I did the final sanding of the top cowl aft edge “in place”.
  3. Put the top cowl in position. I wadded up a towl around the top of the flywheel to get the top cowl in place. For the cowl to spinner gap, I used 3/16″. There’s a debate about spinner gaps on this VAF thread and by the time I was all done with both cowls the gap was more like 7/32″. Tape the cowl in place, and measure back from the 4″ trim line to establish the trim line on the  aft edge of the top cowl.
  4. Take off the top cowl, and cut off the excess, leaving around 2mm aft of the trim line to allow sanding back to the final fit.

Here’s why I would do it differently a second time around. I sanded the top cowl back to the trim line at this point, per the instructions. Then I drilled (from underneath) and cleco’d the aft points of the top cowl into place. The problem with this is, when I put the bottom cowl into place, and cleco’d the two cowl halves together at the front, I found that the position I had the top cowl wasn’t quite right. It only takes a tiny deviation at the front, to change the aft corners a lot. In the end, I decided the cowl had to be right, so I set it up in the correct position around the spinner (allowing for a bit of engine droop over time), adjusted the holes on the top aft edge by drilling (most) of them out to 3/16 (gold cleco’s, and I’m left with a gap of about 1.5 mm across the right rear corner of the top cowl where I’m going to have to do a layup to extend the cowl back to where it needs to be, because as it turns out I trimmed too much off it in the first place. So step 5 below is what I SHOULD have done:

  1. Back when I made the brackets for the Skybolts, I would have drilled the center locating hole #40, instead of #30, just to give more options if I had to finesse locating holes. Now, before putting the top cowl back in place (still with 2mm of excess material on it), I would have made up a few “flaps” of cardboard that are taped to the top fuselage and can be flipped over to show the location of several of these #40 holes across the top cowl aft edge – so that enough holes can be drilled through from the top (I’d do #40, then #30) to secure the top cowl in position as it gets sanded back to fit against the fuselage. Now, with this all prepared, set the top cowl aside, still with ~2mm to sand/trim back on the aft edge. This sanding to size will only be done with the bottom cowl in place – because that’s the way we can guarantee that the top cowl is in the correct position.
  2. Prepare the bottom cowl. I used a laser to establish a center line, by trial and error of the cowl position on a workbench while checking the horizontal measurements at (a) the front, and (b) the rear of the cowl. This center line turned out to be almost exactly in the center of the slot in the lower part of the cowl, but I didn’t want to rely on that – too used to VAN’s mouldings I guess. Removing the lower cowl with a 3 blade propeller can be a problem – I chose one of the common solutions which is to cut the slot for the nose gear leg fairly deep, and I’ll need to install a cover over it as part of the installation procedure. Before cutting the slot, I match drilled four #40 holes into a piece of scrap 0.032″ Alclad, that can be used to retain the aft edge in place after the slot has been cut. Without this retainer plate, after the slot is cut, any attempt to pull up the aft edges of the lower cowl will distort the cowl by pulling the two halves apart around the slot. Now cut the slot. I used a 2″ hole saw, and located the center of the hole 2″ down from the forward most part of the solid surface on this part of the cowl – see the pictures. This places the top part of the hole 1″ from the edge where the honeycomb filler starts. I then used a jigsaw to cut out both sides of the resulting 2″ slot. This created a long slot, wide enough to get around the gear leg without the gear leg fairing – I’ll widen the slot later to fit the fairing. That gives me a bit of wiggle room if the slot is not quite in the center, since this can be checked against the un-faired gear leg once the lower cowl is in position. Tape up the front gear leg with some masking tape, to protect against scratches, and sand any rough edges off each side of the slot.
  3. The untrimmed lower cowl, even with this long slot, is still difficult to get into position with the 3 blade propeller. I used an engine lift to lift the engine up until the nosewheel was off the floor by about an inch, this gives just enough room to get the untrimmed lower cowl into place. By the time I took the lower cowl off again, it is trimmed and all hinges are fitted, and I was able to get it out without the engine lift. This is how I want it – no special tools required to get the cowl off for maintenance. To get the cowl on this first time though, it’s a bit of a trick and definitely takes two people. I positioned the propeller blades as shown in the pictures – the blades are not quite at the 4 and 8 o’clock position – measure from the blades (at around the places where the cowl sides will have to pass) to the floor and get them about even. This was perhaps 5 degrees after the 4  /  8 o’clock position, in terms of normal engine rotation, because of the blade twist. Protect the propeller blades with some tape.
  4. Now, with one person each side, slide the lower cowl up between the blades. It’s a tight fit, but by going a bit sideways and bending the aft corners of the cowl as they pass the blades, you can do it. Another option would be to temporarily remove the bolt holding the gear leg up, but I didn’t need to do this. Once the cowl had cleared the propeller blades, I slid a short table with some padding under the cowl just so it can’t slide back down into the propeller blades.
  5. Crawl underneath, and cleco the retaining plate into place on the bottom aft center of the cowl, behind the gear leg, to hold the two halves together at the constant slot gap of 2″.
  6. See the pictures. I drilled two small holes at the top rear of the lower cowl excess, put a loop of 0.04″ safety wire through each as shown, and then used a light 1″ tie down strap run across the top of the fuselage to hold the lower cowl in place. Don’t tighten it down yet, and when you do, don’t tighten it down much at all – it’s just to hold the aft of the lower cowl in place. You could also use rope, if you’re good at knots.
  7. Lower the engine lift, so the nose wheel is back on the ground, and remote it, we don’t need it any more.
  8. Place the top cowl back on, and insert the six #30 cleco’s that hold the front of the two cowl halves together near the spinner. I had placed a folded up towel around the top of the flywheel so the front cowl assembly sits in around about the correct place.
  9. Make up a pair of metal brackets as shown in the pictures, I made mine in an “L” shape out of scrap Alclad, drilled a #40 hole in the end that will retain the bottom cowl, and carefully drilled two holes (By memory they were 75mm apart) to match the existing holes in the spinner backplate. See the pictures. Screw these brackets, one on the left and one on the right, as shown in the pictures. The bracket part that touches the lower cowl will bend against the lower cowl, but do not drill the #40 holes into the lower cowl yet.
  10. Now, get the front of the cowl in the correct position with respect to the spinner – with the spinner gap you want, even all the way around, centered left/right, and with top/bottom alignment according to what your selected guess is for the amount the engine will drop over time. Most people seem to use about 1/8″ for this guess. Spend plenty of time with this. Also check the alignment of the entire cowl. I didn’t use plumb bobs like the VAN’s instructions, I previously used a self leveling laser to check the left/right alignment of the door sills at the same point on each (rolling one main wheel up onto a piece of 1/8″ thick wood got this alignment right), and then set up the same laser to check the left/right alignment of the cowl intake holes. After making a dozen or so adjustments, most of which simply undid prior adjustments, I tightened up the bottom cowl rear strap (just enough to retain it in place), and carefully drilled #40 through the two spinner brackets and installed cleco’s. This secured the lower cowl into place, and the front of the upper cowl as well.
  11. Never bump the prop from this point on – you want to keep the alignment set up by the two cleco’s into the lower cowl.
  12. Now, using the flip-over cards previously taped to the top of the fuselage, drill #40 through the top center hole of the top cowl, and a hole about 12″ each side of the top. These three cleco’s set the position of the top cowl, although at this point the rear edge of the top cowl is not yet trimmed. Drill these holes out to #30 since the alignment may have been out slightly from the flip cards.
  13. Remove the three cleco’s. Check the top cowl aft edge and convince yourself that the trim line is still correct. Fix it up if it is not. Now, remove the top cowl by removing the six front #30 cleco’s, put it on a bench, and begin sanding down to the trim line across the center section of the cowl.
  14. Place the top cowl back in position, cleco the front, check the aft edge, remove the cowl and continue sanding down to the trim line. I probably did this about 8 times to get the top cowl trimmed. The best tool to use for this is a long perma-grit sanding block. I always hand sand edges that I want to be accurate. Leave the machine sanders in the cupboard. Work from the center of the top cowl, out to each side. As you do so, you might want to drill more cleco holes, if you had done more flip cards. You can’t really trim the side corners of the top cowl unless it is properly secured in place across the top. I don’t know how you do this if you use the Skybolt mounting plates that already have the large hole drilled in it. Tape the cowl in place I guess. I’m glad I made my own brackets.
  15. Once you’re happy with the aft edge of the top cowl, you could release the lower cowl, including the two #40 cleco’s at the front, let it slip down out of the way, and then using a long flexible 90 degree drill extension and the top cowl held in place with the holes already drilled, get your arm up under the aft end of the top cowl and drill/cleco the remaining top cowl aft edge holes from the inside out. This only works if you make your own brackets with #40 (or #30) holes. The top cowl aft edge is now done, and since it was done with the lower cowl in place, it will be right – unlike mine that I need to fill a bit.
  16. Remove the top cowl and set it aside. Move the bottom cowl back up into position, cleco’d to the spinner brackets at the front and held with the strap over the top at the rear. I used a couple of high lift jacks on each lower aft edge to take up any gap at these points.

Enough talk for now, here are a first set of pictures:

  • f48a
    f48a
    Time to get the propeller out!
  • f48zh
    f48zh
    Propeller on, ready for cowl fitting
  • f48b
    f48b
    After trimming cowl to suit 15" spinner
  • f48c
    f48c
    Top cowl after initial trim of aft edge
  • f48d
    f48d
    Material removed from aft edge of top cowl
  • f48e
    f48e
    Top cowl after sanding aft edge to match fuse
  • f48f
    f48f
    Match drilling (from underneath) eventual SkyBolt positions
  • f48g
    f48g
    Establishing centre line of bottom cowl
  • f48zi
    f48zi
    Bottom cowl initial cutout, will need a cover
  • f48zj
    f48zj
    Holding plate used to retain shape during fitting. Marks are from gear leg position.
  • f48h
    f48h
    Bottom cowl in place. Note propeller position.
  • f48i
    f48i
    Bracket to retain front of bottom cowl - right side
  • f48j
    f48j
    Bracket to retain front of bottom cowl - left side
  • f48k
    f48k
    Setting up to mark trim line on bottom cowl AND top cowl over-trim error

Continuing now with the bottom cowl:

  1. Mark the aft edge trim lines, per the plans, using lines previously measured back 4″ on the fuselage.
  2. Remove the bottom cowl, and trim to within under 1/8″ of these lines. Using a long straight (course) permagrit sanding block, sand down close to the trim lines on each side.
  3. Fit the bottom cowl, check for alignment, and continue sanding until the cowl fits properly. I did the final sanding to fit “in place”, by just allowing the cowl to drop down a bit, and spread out on the side I was working on. I stopped at the point where the fit was good, I’ll worry about paint gaps closer to painting time.
  4. With the bottom cowl supported in place, and each pre-drilled aft edge hinge pin fitted, match drill the aft edge hinge pins from the inside out using a right angle drill extension. There may be a few that are hard to get to, skip these and do them once the cowl is removed.
  5. Drop the bottom cowl out, match drill any holes that had to be missed, clean out all debris, and refit the cowl putting a #40 cleco in every hole. Using a countersink cage and a 3 flute countersink with #40 pilot, countersink each hole in turn for an ad3 rivet head.
  6. Clean out any final debris, and rivet the hinge on each side. I used a pneumatic squeezer, and actually did this in place with the cowl dropped down and stretched out a bit.
  7. Refit the cowl with the hinge pins on each side, and the two cleco’s on the front (to the temporary spinner brackets).

Now it’s time to do the side hinges:

  1. Refit the top cowl, allowing the sides to overlap on the outside of the bottom cowl. Now mark a trim line on each side, using a long straight edge. I used a 40″ steel ruler, and a laser which I set up so that the trim line was in the same pitch as the door sill on each side – this is the horizontal pitch when the aircraft is in cruise. This is not horizontal on the ground.
  2. Remove the top cowl, cut and sand down to this trim line on each side, using a long straight sanding block. Refit the top cowl.
  3. Mark a trim line on each side of the bottom cowl, using the top cowl as a guide. Cut and sand down close to this line, but not to it. At this time I also marked in the position of the Aerosport cowl hinge pin covers, and left material forward of this hole on the lower cowl as shown in the pictures.
  4. Fit the top cowl, and keep sanding the bottom cowl sides until they fit properly, with a small gap. At some point during this process I also cut out the holes for the Aerosport cowl hinge pin covers, and trimmed the front section each side of the lower cowl so that it was a good fit with the upper cowl, which wraps around the bottom cowl at each front corner.
  5. Prepare the hinges for each side, and drill #42 all rivet holes in the lower hinge halves. I used a drill press set at 4,000 rpm for this step, to allow drilling accurately and without distorting the hinge half. I elected to use AN257-P4 hinge halves on the upper cowl, so that the hinge eyelets on the lower cowl were below the edge of the cowl. This gives a little bit of extra room when sliding the lower cowl out under the three blade propeller. Clamp the AN257-P3 hinge halves onto the lower cowl (with the upper cowl removed), using a spacer block to set the desired depth all the way along the hinge (I used a scrap of 0.063″ Alclad). Using a right angle drill extension, drill #40 from the inside of the hinge through the lower cowl on each side. Clean out debris, reattach the hinges, and countersink the outside of the cowl for -ad3 rivets. Rivet each bottom cowl side hinge in place. Again I used a pneumatic squeezer.
  6. Set the top hinge half in place on one side, and determine the exact height above the split line where the rivet holes will go. Select a position around the midpoint, and using a foam block wedged/taped between the hinge and a cylinder head (without pushing the side of the cowl “out”), sit the upper cowl in place. Mark where this first hole will be in the upper cowl half, using the previous measurements.
  7. Using an air drill (=> high speed), with a #42 bit, drill this hole through the cowl and hinge. Apply very little pressure, take your time and let the drill bit do the work. I used a 0.025″ metal spacer between the cowl halves for this first hole, which allows for a slightly wider gap after a bit of “spring back” occurs. Pop the cowl up, clean away any debris and de-burr this hole in the hinge, reassemble and put a cleco through the cowl and hinge for this first hole.
  8. Mark hole positions along the length of the top cowl, using a piece of masking tape (see pictures). Working forward and aft of this hole, drill through the cowl and hinge #42 and cleco each hole. I stopped using the 0.025″ metal spacer at this point, and simply eye-balled the gap because I didn’t have three hands. Once all holes are drilled, remove the top cowl, clean up the debris and cleco the top hinge half in place. Ream #40 all holes, clean up, and refit the top cowl, hinge and all clecos. Now, remove one cleco at a time, countersink, and reinstall the cleco. Once all holes are countersink, remove the top cowl, clean up, deburr the hinge holes, and rivet the hinge in place.
  9. Refit the top cowl, slide the hinge pin in for the side just completed, and repeat steps 33-35 for the other side.

That’s it for the initial cowl fit. Next step is to fit the two support fairings supplied by Showplanes that fit around the front gear leg, that support the center section of the lower cowl.

  • f48l
    f48l
    Bottom cowl trim line
  • f48m
    f48m
    Trimming bottom cowl
  • f48n
    f48n
    Sanding bottom cowl aft sides to match fuse
  • f48o
    f48o
    Establishing side trim line
  • f48p
    f48p
    Trimming top cowl sides
  • f48q
    f48q
    Trimming top cowl sides
  • f48r
    f48r
    Riveting hinge to aft edge of bottom cowl
  • f48s
    f48s
    Trimming and sanding sides of bottom cowl
  • f48t
    f48t
    The best tool for sanding long straight edges
  • f48u
    f48u
    Side edges trim/sand complete
  • f48v
    f48v
    Front corners of bottom cowl
  • f48w
    f48w
    Fitting hinge to side edge of bottom cowl
  • f48x
    f48x
    Fitting hinge to side edge of bottom cowl
  • f48y
    f48y
    Match drilling first hole, bottom cowl side hinge
  • f48z
    f48z
    Drilling bottom cowl side hinge
  • f48za
    f48za
    Finished drilling bottom cowl side hinge
  • f48zb
    f48zb
    After drilling first hole #42 through top cowl side hinge
  • f48zc
    f48zc
    Riveting right side hinge to top cowl
  • f48zd
    f48zd
    Right hand side cowl hinge complete
  • f48ze
    f48ze
  • f48zf
    f48zf
    Drilling top cowl left side hinge
  • f48zg
    f48zg
    Cowl sides complete
  • f48zh
    f48zh
    Propeller on, ready for cowl fitting

 

 

Tunnel heater hose [6.5 hours]

Some time ago I added some brackets to the front of the tunnel, so I could secure the rear heater hose. With Control Approach rudder pedals, the hose needs to be secured in the center of the tunnel, clear of the control arms off to each side of the tunnel. I was going to use a 2″ Adel clamp around the scat tube, based on what another RV-10 builder had done.

After assembling this, I didn’t like it because:

  • It was difficult to install the Adel clamp, while lying on my stomach with the seats removed and reaching in under the panel. The rear heater hose has to be sort-of scrunched against the short front heater hose in order to get it positioned in the middle of the tunnel.
  • The large Adel clamp, held by a single bolt, was not very secure and could have a tendency to rotate over time
  • If anything came undone over time, the compacted rear heater hose would push loose items towards the rear, straight into the rudder pedal arms.
  • I still had to come up with a solution to replace the standard F-1051J Scat tube support, since this support interferes with the internally run rudder cables when the Control Approach rudder pedals are used.

After a few minutes pondering these problems, the solution hit me – design and 3D print a pair of Nylon brackets to retain the scat tube. The brackets then simply slide onto the scat tube from the rear. For the front bracket, I bolted the Nylon piece to the Aluminium angle retainer on the bench, slid it onto the scat tube, lifted the rudder pedal arms, positioned the bracket assembly and screwed it into position. I also drilled a pair of small holes into the Aluminium angle in order to add a safety wire each side, that way if the brackets ever came loose for any reason, the assembly could not fall aft and interfere with the rudder pedal arms.

For the aft bracket, I had already a long time ago drilled and dimpled the holes on the right hand side of the tunnel for the standard F-1051J scat tube bracket. The lower of these two holes is close to the right hand rudder cable. It would have been better to raise this hole by about 1/2″, but that is ancient history. I resolved this by using a low profile (AN364) lock nut and embedding the nut into a hexagonal cutout in the bracket, as shown in the pictures. I used a pair of 0.063″ shims on each side, with the holes countersunk, to complete the assembly.

It all worked great, both brackets can be easily removed and reinstalled, so any future maintenance that requires removing the rear heater hose for better tunnel access will be easy.

PostScript:

A couple of other RV-10 builders have asked me for the models, and one questioned why I elected to use the metal shims on the aft bracket. I used the shims simply because I didn’t think my consumer grade 3D printer could do a good enough job of the countersinks, when printing them in Nylon, vertically. In any case, I added an option to the model to have no shims, which widens the aft bracket to compensate for the missing shims, and adds countersinks to the sides to allow for the #8 dimples in the tunnel walls. I’ve added pictures of this version. The three STL files can be downloaded using the following link:

Download

 

  • front_heater_bracket
    front_heater_bracket
    Front scat tube bracket
  • aft_heater_bracket
    aft_heater_bracket
    Aft scat tube bracket, replaces F-1051J
  • f47a
    f47a
    Front Scat tube bracket assembly
  • f47b
    f47b
    Aft scat tube bracket, replaces F-1051J
  • no_shim1
    no_shim1
    Aft bracket "no shim" version, with included countersinks
  • no_shim2
    no_shim2
    Aft bracket "no shim" version, with included countersinks
  • no_shim3
    no_shim3
    Side slopes to match tunnel

RV-14 ADAHRS Bracket [3.0 hours]

I originally mounted a bracket in the empennage for the Garmin magnetometer. Years ago. Then I switched to Dynon avionics, so I was going to have to make a new bracket for the Dynon ADAHRS, and wasn’t looking forward to crawling into the tailcone to install it.

Then I came across the Van’s RV-14 ADAHRS bracket, which looks like a clever design. It goes in the left wing, inside the inner access cover. The RV-14 wings are the same as the RV-10 wings, just shorter. I looked at the drawings and the dihedral appears to be the same, so I ordered the following parts from Van’s:

W-00012A
W-00012B
W-00012C
W-00012D
W-00012E

With these in hand, I prepared an installation for the left RV-10 wing using the following procedure:

  1. Prepare the parts using the RV-14 instructions on page 20-03 of the RV-14 wing manual.
  2. When fluting the W-00012C parts, do not simply hand hold the part and hit it with the fluting pliers. Mark the distance in common with the W-00012B parts, and securely clamp the W-00012C between a block of wood and the workbench so that this area remains flat. Then, use the fluting pliers only on the exposed part – see the picture.
  3. Cleco the parts together. Position on the LH inner bottom wing skin, and verify you have the correct orientation.
  4. Draw a line between the center of the two wing rib holes, these are the fourth holes down from the J strut. Reposition the bracket to be aligned with the center of the access cover, and match drill/cleco the end two holes in the Z bracket through the bottom skin. I used a #42 drill bit, and once all holes were drilled, match drilled with a #40 reamer.
  5. Remove the W-00012A bracket, drill the remaining holes from the Z bracket through the bottom skin.
  6. Remove the Z bracket, de-burr the holes just drilled in the Z bracket and the skin. Dimple the holes for flush rivets, and reassemble all parts.
  7. Keeping the bracket aligned so it is not “twisted”, match drill #40 from the W-00012A bracket into the J strut, cleco’ing as you drill each hole. Enlarge all holes to #30. Disassemble and de-burr.

That’s it. I’m not going to assemble the bracket until I prime the parts, but with the pieces cleco’d together I checked the position and clearances. You can see from the photos that there is plenty of room for the cables and air connections. The OAT sensors can be mounted in the bottom wing skin, near the access cover – see the RV-14 instructions for a typical hole position (I haven’t drilled these yet).

The RV-14 instructions call for countersinking the W-00012C retaining strips for AN426AD4 rivets. The strips are too thin for this, the countersink would need to continue on into the W-00012B parts. I see no purpose for using countersink rivets here, so I’m going to use regular AN470 rivets instead, obviating the need for countersinking the parts.

I have to mount the OAT sensors, make up a wiring harness with tie downs and re-route the air lines. I’ll do these jobs once I’m ready to close out the wings.

  • f46a
    f46a
    RV-14 ADAHRS bracket parts and instructions
  • f46b
    f46b
    Fluting the retainer strips
  • f46c
    f46c
    RV-14 ADAHRS bracket parts prepared/deburred
  • f46d
    f46d
    Drilling the bottom wing skin
  • f46e
    f46e
    Deburring holes added to the bottom wing skin
  • f46f
    f46f
    Dimpled new skin, Z bracket holes
  • f46g
    f46g
    Match drilled holes into J strut
  • f46h
    f46h
    Checking Dynon ADAHRS fit
  • f46i
    f46i
    Bracket in place, old air line routing will have to change.
  • f46j
    f46j
    Bracket cleco'd inside bottom wing skin, all fits OK
  • f46k
    f46k
    Looking up through access cover. Plenty of clearance all around.

 

Engine on, sortof [9.5 hours]

I’ve hung the engine, which took all of 20 minutes once I worked out how best to do it. It’ll have to come off again, so I’m leaving the engine lift set up. It has to come off again for several reasons:

  • The biggest reason – I have to do something with the sump oil line associated with the Barrett cold air induction scheme. There’s a VAF thread about it – here. This whole topic deserves a complete post, which I’ll do once I decide how to deal with it. Suffice to say, it is a nasty issue but until I have a strategy for this I can’t oil the engine.
  • With a B&C 90 degree oil filter adapter, the B&C 462-3H vacuum pad mounted alternator requires a 1.25 inch extension, which I mounted after changing to the correct studs. However, the clearance between the field wire connector and the firewall is not adequate. I’m going to modify the connector and bring the wire out the side so that there is adequate clearance. To do this I have to remove the engine.

While the engine is on, I’ve taken the opportunity to get out all the boxes containing everything that gets added to the engine, and verify that it all fits and I have the correct hardware. I found a few things:

  • The studs that Barrett installed for the PCU-5000X Governor are too short. They are probably the 3C-17 studs that are in the Lycoming parts list. They should be the 3C-19 studs, so I have to order four of these, remove the old studs, and install the longer ones before I can install the propeller governor.
  • The exhaust pipe for the #3 cylinder looks like it will impinge on the induction pipe for that same cylinder. If so, I’ll have to get that pipe modified.
  • I don’t have the engine mounting parts for the A/C compressor. I knew about this.
  • The A/C compressor will get in the way of the left air intake, requiring modification to the intake. I knew about this also.

One job I was able to complete with the engine on – I put a 1″ tie down strap between the front fork and the engine, cranked it down, and was able to easily compress the elastomers enough to get the retaining bolt in – without the engine on to establish the right leverage points, this is just about impossible.

I also made a doubler and drilled the fuselage to install the front ADSB antenna under the passenger seat.

  • f45a
    f45a
    ADSB antenna and doubler added under the front passenger seat
  • f45b
    f45b
    Engine on!
  • f45c
    f45c
    Compressing the elastomers to get the bolt in

 

Transition training [9.2 hours]

I’m an unusual builder – I’m almost 3,000 hours into an RV-10 slow build, and I’ve never even sat in an RV of any kind, let alone flown one! I spent most of July on holidays in North America, including three days at Osh Kosh, and after the main trip was over I traveled to Vernonia, Oregon, where I flew the Factory RV-10 with Mike Seager.

Mike is a great instructor, and has been doing Van’s RV transition training for a long time. Despite some marginal weather at times, we managed to fit in five flights across the three days of August 7, 8 and 9, for a total of 9.2 hours RV-10 time in my log book. We visited 5 different airports during this time, plus the grass strip at Vernonia where Mike has his hanger.

It took me a few hours to catch up with the RV-10, I was hopelessly behind the thing on the first flight. It accelerates and climbs so quickly compared to the Cessna’s I’m used to flying, and the circuit procedures have a different slant as well. During an evening trip to Astoria airport, I finally “got it”, and in perfect conditions with the airport basically to ourselves, I did about ten “stop and go’s” in the fading light.

I’m a bit early doing this training, but couldn’t resist the opportunity to fly a few hours in the USA with such an experienced instructor. The Factory RV-10 costs U$75 per hour, wet (I think it has now gone up to U$80), which is ridiculously cheap especially by Australian standards. Mike explained to me that it is Van’s policy to actively encourage people to fly the aircraft, firstly in order to promote the sale of kits, and secondly to encourage builders to undertake adequate transition training.

I’ll probably do the same thing again in the Northern summer of 2020, when I hope to be close to first flight.

Cabin top/doors – finally DONE! [320.0 hours]

I’ve been on a mission since April to get the fiberglass work on the Cabin Top and Doors behind me rather than in front of me. It’s been a bit of a marathon, the cabin top molding is not famous for its accuracy and everything has to be hand crafted to fit. Here’s the finished product:

I had planned to roll the thing in and out of the workshop to help with this work, but the weather’s been too cold to safely work with the plexi or cure fiberglass, so it’s all been done inside. I’ve had a pair of heaters going in the workshop 24/7 for the past month, and was finally able to turn them off last night. The shop vacuum copped a beating during this time, and I had to regularly clean out the filter.

Here’s all the steps I went through to get this job done. Skip to the end for the pictures.

1. Fit the rear windows

I used Lord Adhesive (available from Aerosport Products) for all windows. The forward surface of the rear windows needs to line up with the aft surface of the doors, which means spacing the windows up from the fuselage molding. I then built up the rear door pillar with a few layers of fiberglass cloth and flox until it matched. There is a flat spot on the left hand door pillar of all RV-10 cabin top moldings, this was the worst place and had to be built up about 5mm – too much for just micro/filler.

I used West Systems G/Flex with some microballoons to fill in any voids not filled with the Lord Adhesive, and trimmed any excess Lord Adhesive with a scalpel. I then taped and scuffed the window (and fuse), and applied 3 layers of fiberglass cloth on the outside. After sanding any high spots, and scuffing, I used regular West Systems epoxy with microballoons and Cabosil to fill and blend the outside surfaces into the cabin top.

2. Paint the inside door sills and cabin top pillars

The lower cabin top pillars had to be blended in, and painted, along with the door sills, to match the rest of the interior. This painting is best done before the front window is installed. Unfortunately, the inside of the cabin top and overhead is already finished, so I had to mask it all off with cardboard and tape. I didn’t want to have a yellow polyurethane primer leak splattered across the ceiling. This all took a fair bit of time, and I wound up spraying each side in sequence rather than together, because I didn’t trust myself leaning across wet paint to get to the other side.

The job took time but went OK, and you can’t tell where the paint transitioned into the existing painted part of the pillars.

3. Install the windscreen

Once again I used Lord Adhesive. It helps to have a second person helping, cleaning up any excess adhesive squeezed out on the inside using Q-tips and white spirit. I used a combination of clecos and weights to hold the plexi in position while the adhesive cured.

3.1 Extend/fill lower edge and prepare for fairing

I scuffed the upper forward fuselage area, acid etched it, and wiped some Alodine over it to prevent the oxide re-forming. I then filled the lower edge of the windscreen using Micro-balloons, with black dye to prevent it being seen from the inside. After the micro cured, I sanded it to align with the outer surface of the windscreen, taped off and scuffed the windscreen. All I used to figure the tape position was a cardboard cutout section with a 7 inch radius.

3.2 Construct the windscreen fairing

Once again using black dye. Preparation is the key to this layup, I cut all of the glass cloth strips, and allowed several hours to do this in one operation. It worked out quite well and a day later I sanded it into the correct shape, using a wooden block cut with a 7″ radius (using the band saw). I used a stick-on flexible perma-grit strip for this operation, which surprised me by staying in place. Gotta be very careful though, not to encroach onto the tape because the coarse perma-grit is a weapon.

After this I switched to 80 grit sandpaper, and finally 120 grit to carefully sand down to the top layer of tape. I used micro to fill low spots. It took a few iterations to get the entire fairing correct, and blend it into the fuselage at each side.

3.3 Glass in windscreen over the top

Fiberglass cloth across the top and down each side, once again fairing it with micro, matching it with the front edge of the door. To do this, I used packing tape on the door as a release agent, slathered micro through a section of the pillar, and closed the door onto it. The following day, a hard yank on the door would release it, and I can sand down any excess.

4 Door edges and cabin top alignment

Whenever I use packing tape as a release agent, I apply it over a layer of masking tape. It is easier to get off, and then any goo left behind simply comes off with the masking tape.

I worked sections of the doors at a time, applying micro to the pillar edges or anywhere that required building up, closing the door with packing tape in place, letting it cure, and then opening the door to release it. This is a good reason to leave the door windows out and fit them last – you’ve got the entire window opening to use rather than the door handle, and in some cases it requires quite a yank to release the door.

4.1 Door gaps, fairing across the top of the door

At this point, the doors closed properly but with basically no gap. Starting at the very top, I used a small piece of 120 grit sandpaper, and worked it from side to side through the gap, closing the door until it jammed, then lifting the door a fraction so I could keep sanding. I mostly sanded the cabin top – since it was micro and easy to sand, but also since the doors already had a nicely formed flat angle which I didn’t want to distort.

Once I could move the sandpaper side to side with the door closed and locked, I moved onto the front and back curves and did the same thing, working my way down each side in turn. Finally I sanded across the bottom and around the bottom corners, getting to the point where I could insert the 120 grit paper, and with a bit of friction still there, slide it all the way around the door.

I measured the 120 grit paper at about 0.01″ thickness. The gap will need to be wider prior to painting, but at this point I left it as is – as long as there is a gap the door is hanging freely, attached by the hinges and the door pins only. Setting up this gap allows the door to drop slightly, maybe a fraction of a mm. This required a bit more fairing work around the top of the doors, to match the door level with the cabin top.

4.2 Bottom of the doors

The bottom of the doors was a close match to the outside of the fuselage, aligned within perhaps 0.5mm across the entire length, but it is a simple matter to match it precisely. Once again, using packing tape as a release agent, I built up the door where required, and the surrounding fuselage area(s) where required, with a thin layer of micro, and then sanded it back to get an exact matchup. This introduces lots of pin-holes which of course have to be filled later.

4.3 Check the seal gap

Since the doors adjusted position a “bit” with the initial gap set, it’s important to go back and ensure that the “seal” gap for the McMaster seal is still correct – between 1/4″ and 5/16″ in my case. I made a few adjustments across the top on each side.

5 Fit the door windows

With the doors an exact match and a 0.01″ gap all the way around the doors, it was finally time to fit the door windows. These are the easiest windows to fit, you can take the doors off and use gravity to your advantage.

6 Optional – prime and fill pin-holes

I elected to spray on some primer and surfacer to seal everything up and fill almost all of the pin holes. I only sprayed two layers of surfacer, sanding most of it off each time. There are still some low spots, it’ll need more work prior to painting, but it’s good enough for now.

All of these operations took two months to complete, and it was with some relief that I took all the masking and protective film off, and wound up with a good result.

 

  • f44a
    f44a
    Fixing in rear window with Lord Adhesive
  • f44b
    f44b
    Window spaced up to align with door
  • f44c
    f44c
    Fiberglass cloth overlaid across window
  • f44d
    f44d
    Micro-balloons fairing filler
  • f44g
    f44g
    Priming the door sill
  • f44e
    f44e
    Topcoat on door sill
  • f44f
    f44f
    Topcoat on door sill
  • f44h
    f44h
    Front window ready for installation
  • f44i
    f44i
    Lord Adhesive applied to rear/top edge
  • f44j
    f44j
    Inside view of front window installation
  • f44k
    f44k
    Metal scuffed, etched and Alodined
  • f44l
    f44l
    Ready for window edge filler
  • f44m
    f44m
    Micro-balloons (with black dye) applied
  • f44n
    f44n
    Window edge filler sanded, window scuffed
  • f44o
    f44o
    Windscreen fairing - some assembly required
  • f44p
    f44p
    Completed windscreen fairing layup
  • f44q
    f44q
    Fairing sanded to shape
  • f44r
    f44r
    Applied micro (with black dye)
  • f44s
    f44s
    Sides/Top glassed in, more filling/shaping
  • f44t
    f44t
    Fairing transition to match the door
  • f44u
    f44u
    Filling low spots
  • f44v
    f44v
    Sanding the door gap
  • f44w
    f44w
    Fairing door/fuse alignment
  • f44x
    f44x
    Fairing door/fuse alignment, some low spots left
  • f44y
    f44y
    Left side door/fuse alignment fairing
  • f44z
    f44z
    Fitting door windows
  • f44za
    f44za
    Fitting door windows
  • f44zb
    f44zb
    Glass cloth for door windows
  • f44zc
    f44zc
    Door windows glassed in
  • f44zd
    f44zd
    Preparing to spray primer and surfacer
  • f44ze
    f44ze
    Preparing to spray primer and surfacer
  • f44zg
    f44zg
    Light coat of polyurethane primer
  • f44zh
    f44zh
    First coat of surfacer
  • f44zi
    f44zi
    Filling pin holes
  • f44zj
    f44zj
    Tearing down after spraying
  • f44zk
    f44zk
    Removing window tape, protection
  • f44zl
    f44zl
    Cabin top and doors - finished!
  • f44zm
    f44zm
    Cabin top and doors - finished!
  • f44zn
    f44zn
    Door gap
  • f44zo
    f44zo
    Front view

Up on the gear [10.5 hours]

I agonized over how best to raise the airframe to install the gear legs. I gathered some family muscle to lift it up onto a workbench, but aborted the attempt after it became clear we couldn’t do the lift with enough control.

I borrowed a 500kg lift table, removed the handle, and made up a frame that provided support under both the main and rear spar. I wanted a backup in case there were any problems with the lift table, so I crudely extended the forks on the tractor, added a bit of padding, and held these an inch below the airframe, as shown. As it turns out, the table did fine and the tractor was not required.

I fitted the left main gear leg and wheel, then had to cut the old dolly apart (committed at this point!) to get it out of the way and fit the right main gear leg and wheel. After fitting the nose gear, I let the table down and the fuselage settled in a nose high position (because of the missing engine weight). It looks awkward like this, but it’s still quite a milestone to get it up onto the gear.

  • f43a
    f43a
    Raised by lift table, getting backup tractor forks in position
  • f43b
    f43b
    Raised by lift table, tractor forks for safety
  • f43c
    f43c
    Raised by lift table, tractor forks for safety
  • f43d
    f43d
    Cutting away the old dolly
  • f43e
    f43e
    Left main gear on, ready to do the right
  • f43f
    f43f
    Left main gear on
  • f43g
    f43g
    Both mains and nose gear on
  • f43h
    f43h
    Back down, on the gear, nose high with no engine weight