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Archive for March, 2013

Inlet Ducts and Baffle Seals – 9 hrs

March 31, 2013 Leave a comment

Sunday Mar 31, 2013

The post covers work done the week of March 25th through March 31.

I mixed a batch of epoxy and microlight and applied a layer to the inlet ducts to smooth out the surfaces of the layups provide a smooth transition for the engine baffles. After sanding the microlight the surface is looking pretty good.

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While the cowling was off I took the opportunity to safety wire the upper alternator bracket bolts.

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With the inlet ducts in shape I could now finish trimming the forward engine baffles on the sides and adjacent to the ring gear. I was surprised how much I had to trim off and it took quite a few iterations to get it done because the visibility to the baffles is so poor in these areas. But after several hours of work on Friday and Saturday I got the baffles trimmed to a gap of 0.5 inch as best I could tell and then started on making templates for the rubber seal material. There is virtually no guidance for how to do this in the plans so I browsed the forums and other web sites to get some ideas. Here is my first attempt using brown wrapping paper for the templates.

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This side view of the forward baffle shows the swooping line I trimmed to match the inlet duct.

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The rear rubber seals seem pretty straightforward so I cut the first piece and attached it with clamps to check the fit.

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Since that looked good I cut the other rear rubber strip and then laid out rivet holes and drilled #40 using clecos for now. Two pieces done and many to more to go.

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Categories: Cowling, Engine Baffles

Inlet Ducts, Oil Door, Water Leak – 10 hrs

March 24, 2013 Leave a comment

Sunday Mar 24, 2013

This post summarizes the work done Thursday Mar 21 through Sunday Mar 24.

I have been doing a lot of research on the web about installing the inlet ducts on the inside of the top cowl. These fiberglass pieces funnel the air flow from the cowl nostrils to the engine cylinders. They also play an important role in the sealing of the engine baffles. That is the part I have been trying to figure out. The main question is how the rubber seal strips transition from the inside surface of the cowl to the inlet duct surface and the nostrils. From my research I concluded that the inboard edge of each duct needs to be filled in and smoothed out so the seal can ride up gently along a continuous surface. On the outside edges you can do the same or trim back the ducts to clear the side baffles and allow the rubber strips to seal all the way up to the nose of the cowl. I decided to extend the ducts on both sides because I can visualize better how the seals will work.

So the work started on Thursday night when I installed the cowl and marked where the baffle edges run directly below the cowl surface. This gave me an outline to help align the ducts. I placed the ducts so the flanges fit well against the cowl surface and I aligned them midway between the baffle lines. I drilled several #40 holes through each duct for clecos. I removed and sanded the ducts for bonding. I mixed up a thick batch of epoxy and microlight and applied a good thick bond on each faying surface and clecoed the ducts back on. Then I put the top cowl on the fuselage with the bottom cowl, inserted the hinge pins and let the epoxy set 24 hours. By the time I got home from work Friday it was set and I removed the top cowl and took this picture. You can see some of the baffle lines on the inboard edges.

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I also noticed some water on the floor of the garage by the work bench on Friday evening. More about that later.

On Friday night I also did some more work on the oil access door. I want to make the fit between the door and the cowl look “production-like” so I applied packing tape around the perimeter of the door and mixed up some epoxy with microlight and with the door installed applied the mix all the way around the seam of the door to the cowl. I plan to sand this smooth after it sets.

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Step two with the inlet ducts is extending them and building ramps for the baffles. Another recommended step is closing out one side of each duct to prevent air from flowing from one side to the other between the ducts and the top cowl. This is a common leak path for inlet air. I decided to close out the inboard surfaces because I already have to extend those edges further provide a good sealing surface. On Saturday I picked up a can of Great Stuff big gap spray-in foam at Home Depot to use in mold making. I shot in the foam on the inboard edges (yes, I overdid it a little). This foam takes up to 8 hours to cure, especially when it is thick. In the mean time I covered some thick paper strips with packing tape and attached them to the outer edges of the ducts to use as simple molds to support fiberglass just to extend the surface outboard a half inch or so.

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I isolated the source of the water on the floor – another water leak! This is the second water leak in three months. The last one did $8000 in damage to floors, walls, etc. I’m not liking this. Another call to the plumber to start the investigation of the source. In the mean time the water is turned off at the main valve. Fast forward to afternoon on Saturday and the leak is located in the wall adjacent to a bathroom next to the garage. The leak is about 1 inch above the concrete slab in a copper line and the plumber tried to fix it but to no avail so it looks like he will have to reroute the line tomorrow. Not good news. While the plumber was working I sanded the epoxy/microlight I applied to the oil door on Friday. The door released easily from the epoxy due to the packing tape after I sanded the surface down flush. I opened the gap around the perimeter a little by sanding the edges of the epoxy to get enough clearance for the door to operate easily. I’ll have to remove a little more later to allow space for paint build-up but I’ll let the painter decide how much is necessary. For now, the gap looks great.

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Sunday morning I was waiting for the plumber to arrive and I carved the excess foam off the inlet duct ramps and shaped the surface by sanding. In this picture you can also see the fiberglass extensions I laid up on the outboard edges of the ducts using two layers of 8 0z Rutan BID glass. One caution here: the inlet ducts can interfere with the engine main starter ring gear. I had to be careful to shape the foam to provide at least a finger of clearance (about 5/8 inch) between the ring gear and the foam.

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I had time before Joe the plumber arrived to apply two layers of 8 oz BID on the foam molds. In the next picture it is starting to cure. The dots on the surface are just the marks I made on the glass for cutting to the odd shape for the duct surfaces.

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By mid afternoon I had epoxy that was curing nicely (it was about 70F in the garage) and holes in the walls. Looks like about $1500 in plumbing repairs this time plus the cost to repair the drywall and repaint. When does it end? I guess the purchase of my avionics will be delayed more than expected.

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In the late afternoon I trimmed up the extensions on the outboard edges of the ducts and sanded them smooth. There should be plenty of material there for the rubber seals to ride on without worrying about them each time I install the top cowl. I still plan to use some thick epoxy/microlight to smooth out the duct surfaces, especially in the transitions to the nostrils and where the flanges attach to the cowl.

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I also sprayed a coat of UV Smooth Prime on the oil access door to protect it (and make it look prettier) until the whole cowl is painted some time down the road. I also riveted the camloc latches to the door. Wow, the door looks close to production quality now. I am very happy with how this turned out.

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Here it is held open by the hidden hinge spring. It really snaps up sharply. Hopefully the dual latch setup will prevent inadvertent opening in flight, something I have read can occur with single latch setups.

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Categories: Cowling

Finished Mounting Oil Cooler – 14 hrs

March 17, 2013 Leave a comment

Sunday Mar 17, 2013

Thursday: I attacked the cut-out in the #4 rear baffle for the oil cooler on Thursday night. I don’t have a decent metal cutting blade for my jigsaw so I drilled holes in the four corners and cut the opening with a cutting wheel on my rotary tool. I cleaned up the rough edges with a file. This photo is when I put the oil cooler doubler back on to check the fit.

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Next I put it all back on the engine so I could check the fit again and make sure the position of the oil cooler looked good relative to the #4 cylinder – not that I could do anything about that now except start over with a new rear baffle. But the position looked fine and the clearance of the oil cooler flange to the engine mount tube is good also. I don’t think I’ll even need to trim the flange. You can see the oil cooler brace sticking up in this picture well above the profile I trimmed to earlier. I went after that next.

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Friday: I marked a rough trim line on the oil cooler brace by eye just to remove enough material so that I could put the top cowl back on and measure for a final cut using the paper clip method. Turns out my eyeball cut line was just about right and I only had to remove about another 1/8 inch of material after that to get a gap of about 7/16 between the oil cooler brace and the cowl. After finishing that I scrubbed up a few new parts, put on a coat of alodine, and began riveting the left rear corner baffle assembly together. I started by riveting the new custom flange onto the oil cooler brace.

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I also made a cut out in the rear baffle for the ignition wire seal. You can see it in this photo next to the oil cooler doubler. It is the oval hole with two small holes above or below it. This is the only logical place for this on the left side. I continued riveting but I could not find two K1000-3 nut plates in the kit so I left the two closest to the ignition wire cut-out unriveted for now.

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Saturday: I put the left rear baffle assembly back on the engine to confirm that everything looks good. I’m sure I could make faster progress if I didn’t keep doing this but it builds confidence when the plans are a little light on detail.

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The next step on my short list was to make the cut-out for the ignition wires on the right side and start installing blast tubes for the P-Mags and the alternator. The plans don’t say where to put the ignition wire seal on the right side so I measured it out about the same distance from the centerline as the left seal. That looked good as far as wire routing is concerned. I also played around with potential routing for the blast tube for the right P-Mag and marked a location on the right rear baffle. I stopped to search the forums to get advice on where to locate these items but I could find nothing. So I went ahead and cut the holes. It was only after I put the parts together for a fit check that I realized I had done this without having the oil filler tube installed. When I put that in I saw that the ignition wires are uncomfortably close to the filler tube. In fact the tube blocks the logical path to the P-Mag. Why didn’t I think of that before cutting the hole for the wires? This is not a complete show stopper issue but it is not ideal either. I stopped there for the day and thought about it overnight.

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Sunday: Well I found the K1000-3 nutplates I was looking for on Friday. They were in a bag with AN fittings for the baffle subkit. I looked in the logical place -the hardware bag for the baffle subkit – but I didn’t think to look in the AN fitting bag. Just as well because I needed to make a bracket to attach to the rear baffle for a diagonal stiffener and those two nutplate locations are the ideal place to attach it. The diagonal brace is another element of reinforcement for the left rear baffle to head off the cracking issues that some people have seen. So today I made the bracket from 3/4 x 3/4 x .032 angle stock, alodined it and riveted it on with the newly-found nutplates. It is visible in this picture next to the cut-out for the ignition wires.

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Another task was to make tubular spacers for the oil cooler flange bolts. These permit the oil cooler to be bolted on with both the front and rear flanges. Made from 5/16 aluminum tube they are just cut to length (and I alodined them). But another modification recommended in the forums is to make washer plates to go between the tubular spacers and the cooler flanges. These spread the load out over the surface of the flanges instead of concentrating it in a thin ring around each bolt. Some people use steel for these plates and I am sure that is stronger but I used 1/16 aluminum sheet cut 1/2 inch wide. Since the oil cooler flanges are aluminum and the spacer tubes are aluminum I prefer to make the plates out of aluminum also to keep the materials similar for galvanic corrosion reasons and aluminum is much easier to work anyway. So here you can see the results of my efforts. The parts are all alodined and installed except one bolt which I need to order from Spruce. The kit includes three long bolts and one short bolt for the inboard flange but I have enough clearance to the engine mount that I can use four long bolts which is stronger so I will order one more from Spruce.

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Here is a photo of the left rear baffle installed with the ignition wires in place and the bracket installed for the diagonal stiffener (barely visible behind the ignition wires). I still need to decide how to make that brace. Thin wall aluminum tubing with flattened ends is one option. You can also see how the ignition wires fit snugly on the ends of the dessicant containers in place of the actual spark plugs. That’s nice that they made them that way. You can also see the hole I drilled for the blast tube for the left P-Mag.

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Overnight I figured out a plan to recover from my mistake in locating the right ignition wire seal. It was clear that I should have cut the ignition wire hole further outboard to avoid the oil filler tube. I could cut a new hole for the seal in a more outboard location but what about the hole I already cut? Well I still need to install an AN fitting for the fuel purge line though the right rear baffle so I decided to make a cover for the badly located ignition wire seal and install the fuel purge fitting there. That fitting can have a 90 degree turn on the aft side of the baffle so it will not interfere with the filler tube. I removed the right rear baffle and made the modifications. I made two cover plates; each .032 thick with holes for bolts through the existing holes in the baffle and a new hole for the purge line fitting. I also cut a new hole for the ignition wire seal further outboard. In this photo you can see it assembled temporarily. I had the AN fitting on hand so I installed that also. The hose run from the purge valve to the fitting is pretty direct but I may change the fitting on the purge valve to give an L-bend run instead of an S-bend because the distance is rather short.

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This photo shows the new setup from the aft side. You can see that the ignition wires are well clear of the oil filler tube now and the AN fitting is pointing almost straight down. A hose will run from there to the firewall. Although not perfect I am satisfied with this redo. The only evidence of my mistake is the doubler plates on the baffle for the purge fitting.

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Started Installing Oil Cooler – 3.5 hrs

March 12, 2013 Leave a comment

Tuesday Mar 12, 2013

I got a decent view of the engine baffle clearance tonight by removing the lower cowl and installing the upper cowl alone. Looking up from below I could see that the gap is pretty uniform meaning the baffle edge follows the contour of the cowl pretty well.

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With the cowl in this configuration I took the opportunity to trial fit the oil cooler. The plans say to mount the cooler as high as possible without hitting the cowl. I take that to mean with about a 1/2 inch gap to the cowl. Doing this will maximize the air flow through the oil cooler because the lower portion is blocked by the #4 cylinder. So this is why I have not installed the oil cooler to this point – because I first needed to trim the tops of the engine baffles to allow the upper cowl to be installed in its proper position so I could then locate the oil cooler on the #4 cylinder rear baffle as high as possible. This photo shows the cooler as high as I dare mount it.

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With the cowl off you can see how high the oil cooler is placed and in this photo I have cleco’d in the oil cooler brace which mounts in front of and above the oil cooler. This part strengthens the rear baffle and provides a continuous surface along the aft baffle for the rubber seal material, eliminating the jog which would be difficult to seal. You can also see the spark plug wires in this photo because I started looking at how to route these.

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In this next photo you can see the oil cooler brace from the front. I found a problem with this part. If I mount it high enough that it does not block the oil cooler there is not enough overlap with the side baffle to attach it and to attach the rubber seal material. Conversely, if I lower it so I can get at least one rivet on the outboard side flange into the side baffle the lower flange overhangs the oil cooler air passages by about 1/2 inch.

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I decided to modify the oil cooler brace by adding a new flange that turns upward on the rear baffle rather than downward. I made this angle from .032 sheet and match drilled it to the brace and the rear baffle as you see here. This will allow me to cut off the flange that hangs down so it will no longer block the oil cooler.

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This led me to tweak the position of the oil cooler slightly downward so everything would line up nicely with adequate edge distances. So now it is slightly further away from the upper cowl but not by more than 1/4 inch so cooling should not be impacted much. In this photo I have match drilled the oil cooler doubler to the rear baffle and marked the opening for the cutout which I will attack next time.

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Finished the Big Trim – 6 hrs

March 10, 2013 Leave a comment

Sunday Mar 10, 2013

This morning I decided to use the paper clip method to measure for the second trim cut on the tops of the baffles. After the first cut yesterday to get close to the final fit I thought the paper clip method might be more accurate for the final steps. In this picture you can see the array of paper clips I placed on the tops of the baffles before mounting the top cowl.

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I installed the top cowl carefully and put in the hinge pins. Then I removed the top cowl to see how far down the paper clips had been pushed. I placed marks 1/4 inch below the tops of the paper clips for the next trim line. Then I removed the cowl and baffles again, made the trim cuts, deburred the edges, reinstalled the baffles and cowl, and check the results. It took me three more iterations but eventually got the baffles trimmed to between 3/8 and 1/2 inch from the inside surface of the cowl. That’s all I did today but it feels good to have this tricky step completed. Here is how the baffles looked after trimming.

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Categories: Engine Baffles

Started the Big Trim – 6.5 hrs

March 9, 2013 Leave a comment

Saturday Mar, 9, 2013

Today is the day to start the “Big Trim” which is trimming the top of the engine baffles to clear, yet match the contour of the upper cowl. But first I needed to finish a few details. I had to deburr, degloss and alodine the clip and conical gusset on for the right air inlet. Then I riveted those parts to all the other right inlet parts. The completed inlet is shown below on the engine.

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I also had to make a new bracket for the right aft baffle. The stock one was about 1/8 inch too long and try as I might it would not fit. Here is the new bracket which looks just like the old bracket but it is slightly shorter.

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The stock baffles are all too tall and need to be trimmed down to achieve a gap of 3/8 to 1/2 inch to the inside surface of the top cowl. This allows room of the engine and baffles to move a bit on the flexible engine mounts and not strike the cowl. The gap will be filled by a set of rubber seal strips. I read a tip on the forums on how to get a good measurement for the first trim cuts. You can see in the picture below that it involves mounting the top cowl on  “spacers” 3 inches above the normal position. I used paint sticks and clamps to support the top cowl. This is well clear of the baffles and allows just enough room to get a hand inside to mark the cowl. I attached a pencil to a stick with a strip of aluminum attached to provide a 3-inch offset. I reached in and ran the marking tool along the inside surface of the cowl to mark a line on the sides of the baffles 3 inches below the cowl. That’s Rob, my younger daughter’s boyfriend who came by to hang out with me for a while today and give me an extra set of hands.

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Then we pulled the cowl off to examine the markings. I repeated the process a couple of times to see if the results were repeatable. There is plenty of room for error since tilting the marking tool changes the line of the pencil on the baffle. So being generally leery of cutting too much away I made the first cut about 1/4 inch above where the markings appeared to be. This required us to remove the baffles from the engine, trim them, deburr them, and put them back on. After the first cut the baffles were still preventing the cowl from seating fully but just barely and I could see that the trim line nicely matched the profile of the cowl. It’s hard to get a good picture but this next one is looking up inside the left nostril. The left side baffles are contacting the cowl right where it is curving down to the hinge line. It looks like the process worked pretty well and I could have been more aggressive with the first cut, but I think it is better to be conservative and make an extra cut or two rather than risk cutting too much off. Tomorrow I will make another trim cut.

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Categories: Engine Baffles

Small Baffle Parts – 3.5 hrs

March 7, 2013 Leave a comment

Thursday Mar 7, 2013

Continuing to work on the engine baffles I made several of the small clips for the area around the inlet ramps over the last few evenings. The baffle kit includes .032 x 1 x 1 angle stock for these so the job was to measure dimensions from the assembly then cut and trim the parts to fit. I laid out the hole pattern on the clips and pre-drilled those first, then placed the clips on the baffle assembly and match drilled. There is one clip on the right side shown in this next photo.

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There are two clips on the left side and the long one must be match drilled through the bracket underneath the inlet ramp as well so I carefully measured and laid out the holes for those parts. After I determined where the overlapping hole should be I pre-drilled in the bracket underneath and match drilled from the bottom through the inlet ramp and the clip on top. All the edge distances turned out fine.

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I also made two new little clips that help secure the front and rear side baffles. One on each side.

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It seemed like a good time to deburr all the new parts and give them a coat of alodine so I processed those tonight and began riveting some of the baffle parts together. I started on the left inlet side. I riveted the inlet ramp to the long stiffener in front of the cylinder, I riveted the two brackets under the inlet ramp (you can’t see those in this picture), and I riveted the two clips to the front baffle next to the starter ring gear. With the front baffle cleco’d to the inlet ramp I put the parts back on the engine to make sure they can be installed in one piece and to verify the fit is good before riveting the front baffle to the ramp. I also wanted to mark the front baffle for trimming along the front edge. It overlaps the cowl nostril way more than necessary so I plan to cut that down to about 3/4 inch overlap.

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