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Archive for July, 2013

Prop Arrives – 2 hrs

July 27, 2013 Leave a comment

Saturday July 27, 2013

I was starting to get a little upset with Catto Props. I ordered my three blade prop in January when they said the lead time would be 6-9 weeks. I was given a projected ship date of 4/1. After many delays I was finally told it would finally ship on Friday 7/19. FedEx had it in their tracking database but no information was listed except “Shipment information sent to FedEx”. I called Catto on 7/25 and Nicole told me it was due for delivery on 7/26. At 7 PM last night it had not arrived so I was mumbling under my voice. Denise and I sat down to watch a movie together and at 9 PM when it was over I notice a big package by the front door on the porch. Wow, Fedex did not even ring the bell. Here is the box. I wonder what could be in there?

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I had to unpack it to get a look. This thing is ready to chop some air.

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This morning I sprayed a coat of high build primer on the lower cowling to protect it from UV (and to make it look better). I am researching primer sealers I can use over this until I am ready to paint.

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Categories: Cowling, Firewall Forward, Prop

Riveted Rudder Cable Fairings – 1 hr

July 25, 2013 Leave a comment

Thursday July 25, 2013

Tonight I riveted the rudder cable fairings onto the side of the aft fuselage. I also worked on the electrical schematic for the annunciator lights.

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Categories: Aft Fuselage, Fuselage

Finished Sealing Cowl, Started Radio Stack – 16 hrs

July 21, 2013 Leave a comment

Sunday July 21, 2013

Apply epoxy and sand… apply epoxy and sand. That’s what I did for hours this weekend. The lower cowling section has a huge amount of surface area and it has taken longer than I hoped to get the surface sealed with epoxy and to fill all those pits and crevasses in the honeycomb surface. I had to do it in three phases; first for the bottom surfaces and then two more times for the side surfaces. I lashed the part to the work bench on it’s side so the epoxy would not run off the surface due to gravity.

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Finally after many hours of work starting Friday night and completing on Sunday afternoon I finished the project. The outside surface is sanded and ready for a coat of primer now. That’s when I ‘ll find out where the minor surface flaws are located.

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Between phases of fiberglass work while waiting for epoxy to cure I installed this microswitch for the canopy. It will turn on an annunicator light on the panel when the Master switch is on and the canopy is not locked.If you are interested the switch is part number 7658K15 from McMaster-Carr. I actually bought three different switches but this one worked the best. It has holes for #2 screws so I made a small butch plate and installed flat head screws from the back side with nuts on the near side. I will stake those nuts with a dab of epoxy since they are not self locking nuts.  The holes in the butch plate are for #4-40 screws which I mounted into holes I tapped in the latch hook. If necessary I can adjust the engagement position of the switch by slotting the upper hole in the butch plate. I may add a little aluminum cover to protect the switch lever since it is somewhat fragile while exposed.

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This view shows the canopy fully latched and the switch closed.

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I also prepared to rivet on the rudder cable fairings on the tail. This photo shows the surface masked with electrical tape for buffing and priming.

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And last but not least I started building the radio stack for the instrument panel. This stack includes a PS Engineering PMA5000EX audio panel, Garmin SL40 comm radio and space for a Garmin GTN650 WAAS GPS. I am starting with the rib sections I cut off the stock instrument panel structure to make room for the dual Dynon displays. I cut two sections of .063 x 3/4  x 3/4 aluminum angle. The first job was drilling those angles with holes that match the pre-drilled holes in the ribs for nut plates. Those angles will be the main structural brace for the panel. Then I carefully measured and aligned and marked and remeasured to drill holes through the angles and the ribs for the audio panel tray.

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The trick with those holes is placing them so they straddle the previous holes because the nuts may interfere with the #8 nutplate to be installed later. You can see that in this photo. Shift the tray up or down a small amount and the nuts would be impossible to install with the nutplate installed where the cleco is located.

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The rest of the trays will be no problem because they are all well clear of the other nutplates that will be on the bottom of the ribs. So here is stage one of the panel. The audio panel is in the tray attached to the ribs with the reinforcement angles. Still a long way to go.

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Mostly More Cowling – 10 hrs

July 14, 2013 Leave a comment

Sunday July 14, 2013

Most of my time this weekend was spent working on the cowling but I also did a few other things just to keep things interesting. First I made labels for my annunciator panel lights. All I did was print out the labels on plain paper on my laser printer and cut them out to fit in the lights. When you pull the colored lens off each lamp there is a diffuser underneath. I put the label between the diffuser and the lens.

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I also made a handle for the canopy release mechanism. The stock handle is long enough to extend out through the instrument panel. I cut it down so it just protrudes past the subpanel when the mechanism is in the latched state. I slotted the tube and drilled a hole for the link pin.

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Here is the handle installed on the mechanism in the latched state. I will install the cotter pin later because I know I still need to remove the subpanel to cut a hole for the radio stack.

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This view is from the aft side. That adel clamp is not installed yet but I marked the location for a hole and I will install a nutplate there when I pull out the subpanel.

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I also started installing the VHF com antenna. Mine is a Comant CI-122 and I am installing it below the pilot’s seat in the most outboard bay. I made a doubler out of some .032 stock alclad including two angles to stiffen it up side to side.

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I located it aft of the main spar and as far forward as I could to keep it as far from the ADSB antenna as I could. That put it right under the aileron control rod. I will probably have to install a 90 degree coax connector on the cable for the antenna to keep the cable away from the control rod. I still need to rivet the doubler in place.

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But most of my time was spent on the cowling. I picked up some high-build primer at ACS on Saturday and sprayed the top cowling section. Boy it is nice to see the pepto pink disappear. I put on three light coats of primer. After it dried I sanded it out with 400 and 600 grit paper and it is nice and smooth. The oil door was sprayed separately.

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The lower cowling still needs a lot of work on the exterior. It is covered with thousands of pits due to the honeycomb layup. So I started filling the pits with slightly thinned epoxy. I started with one coat squeegeed on with a single edge razor blade on the surfaces that are more or less horizontal in this view. It does no good to apply it to the vertical surfaces because it just runs out of the pits. When the first coat was cured about an hour or so and was stiff and sticky I brushed on a second heavier coat – hopefully enough to completely fill the pits. Now I will let it cure so I can sand it out to see if another coat is required.

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Installed EGT Probes – 3 hrs

July 7, 2013 Leave a comment

Sunday July 7, 2013

You only get one shot to drill the holes for the exhaust gas temperature probes – unless you want to ship the pipes back to Vetterman to weld up the holes. Consequently, I researched the subject of where to mount the probes and how to orient the wires. The Dynon manual says they should be 2 to 8 inches from the cylinder. It also says “This spot should be on a straight portion of the exhaust manifold, as this provides a better fit for the hose clamps. For best results, mount all probes the same distance from each cylinder.” Well that turns out to be impossible with the Vetterman crossover exhaust. The #3 cylinder is the main driver and it has a welded fitting that is about 3 inches below the flange that prevents the probe from being installed anywhere but just above it. You can see it in the center of the picture below. I put the probe 2.6 inches from the bottom of the exhaust flange. Keeping consistent with the 2.6 inch offset causes the probe to be on the bend of cylinder #1. But my research from other builders indicated this would not be a problem. To maintain cowl clearance I pointed the probes forward on this side away from the respective spar plugs so as not to block them. The wires will loop forward and upward and join the spark plug wires clamped to the valve covers.

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On the left side the probes are also 2.6 inches from the flange but here they are oriented pointing aft, again away from the spark plugs. The hose clamps on all the probes were too long, leaving more than 2 inches of “tail” poking out so I cut the excess off with a dremel cutting disc. Now I need to route all these wires!

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I started another small project today that has been on my To-Do list for quite a while. I made a plate to hold all the LED annunciator lights for the instrument panel. In the photo you can see the dimensioned sketch I used to make the plate and the functions designated for the lights. These lamps operate on 12 Vdc and don’t require external resistors. I’m still working on the wiring plan and I’m trying to find a way to add a push-to-test function for the entire annunciator array.

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More Cowling Finishing – 12 hrs

July 6, 2013 Leave a comment

Saturday July 6, 2013

A long four-day holiday weekend is a great opportunity to make some progress on the 7A. This cowling is making me crazy though. It is so time consuming and seems to go on forever. I focused first on the interior of the lower cowling. I located some high temperature white engine enamel at the auto part store so I bought two cans to paint the interior of the lower cowling. I used two light coats followed by a heavier coat. And this is how the job came out.

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After it cured for a day I started laying out the pattern for the heat shield. I am using a method described on VAF that combines Fiberfrax from ACS and the self-stick aluminum foil from Vans. With the lower cowling installed I reached in and put down small strips of blue tape around the areas where the exhaust pipes are closest to the cowling. The shape is irregular because the exhaust is not symmetrical about the center line. Then I took the lower cowling back off and started making a pattern using brown wrapping paper. Nothing is flat so the shape is hard to get right without making a pattern. I used multiple pieces of paper taped together to give me the final shape. I split it along the center line and along the edge of the lower protrusion for the air box because it is really hard to make a single flat pattern conform to the complex geometry.

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I used the pattern to transfer to the aluminum foil. The Fiberfrax was then cut to fill the area closest to the pipes and the foil overlaps it and goes several inches beyond on the sides. This is 1/16 thick Fiberfrax from ACS. I ordered 3 feet (x 24 inches) and that turned out to be just right. This photos shows the first segment installed with the Fiberfrax laminated underneath.

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And here it is with all four segments installed including the segments down in the lower recess. Funny – it looks like some kind of bird. It seems to be well adhered so I’ll leave it this way. If the edges start to lift later I can tack them down with Pliobond or epoxy.

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I spent the most time on Thursday through Saturday working on the exterior of the upper cowling filling the thousands of small depressions on the surface. I realized that one coat of epoxy was not enough so I sanded the exterior surface and applied two more coats. Here’s a major tip. Don’t apply a coat then wait for it to fully cure. When the first coat is at the tacky stage, immediately apply the next coat so you don’t have to sand the surface between coats. Saves a lot of time. Here is the upper cowling with two coats applied and curing.

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Hours and hours later the exterior is sanded. There are only minute traces of the original dimples left now so next I will apply some filler primer for a sealer coat and see what defects are still visible.

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I picked up another couple of cans of white engine enamel at the auto parts store and painted the interior of the top cowl on Saturday afternoon.

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Categories: Cowling, Finishing Kit