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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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Finished Canopy Hinge Blocks and More – 7 hrs

April 8, 2012 Leave a comment

Sunday Apr 8, 2012

This has been an unusual week. We had relatives in town from Wednesday evening through Saturday night so my work on this project was in little short sessions whenever it was convenient. So this post summarizes all the things I did since Monday April 2.

Tuesday Apr 3

On Tuesday I worked on the C-710 pushrod for the canopy release side handle. The rod must be cut to length, drilled out with a #3 bit and tapped to 1/4-28 on each end. The plans say to cut the length to fit at assembly but there is an overall length provided on the drawing so I cut it a little longer than the drawing. I can trim it a bit later if necessary. As shown below, I drilled the ends and tapped them for the rod ends.

Wednesday Apr 4

On Wednesday I started working on the links of the canopy release. These are a royal pain in the behind because they are steel and you have to drill holes on the ends for cotter pins and slot them for the release pins and release shaft. I drilled the cross holes with my drill press. I marked the locations and drilled with a #40 bit,then enlarged to #30, then #12. You have to be careful to make sure the two holes are parallel.

Here is a shot of the short link with the cross holes drilled.

Then came the trickier part which was cutting the slots. I used a reinforced cutting wheel on my dremel tool for the basic cut. The wheel is about .050 thick and the desired slot width was .060 so this required a steady hand. The first one took a while to cut as I did it very slowly. I finished the slot with a tiny file. More on this later.

Thursday Apr 5

Thursday night I had a little bit of time so I made the spacers for the elevator pushrod where it attaches to the elevator horns. You can see them installed in this shot.

I also took the vertical stabilizer off so I could prime the shims and parts that connect it to the fuselage.

I received the new C-617 UHMW bearing block in the mail today from Vans. The photo below shows the old scrap block beside the new block. It did not take long to transfer drill the two #10 holes from the scrap block. You can bet I was careful to not allow the drill bit to chew up the block the way I did last time. On the drill press I now apply smooth downward pressure while drilling through then shut off the drill before trying to back the drill out. That seems to work pretty well.

Saturday Apr 7

On Saturday I had the chance to finish installing the new C-617 block on the forward fuselage and drill the 1/4 inch hole for the canopy latch pin.

Because I have read much about the trials of fitting the canopy frame I decided to rivet the canopy frame skin onto the weldment and perform and check of the fit with the forward skin. The photo below shows what that looked like.

As expected I found that the skins would not meet leaving a gap of about 0.100 inch as you can see below. It looks like the shims between the C-617 and C-618 blocks is preventing the canopy frame from sliding forward any farther. Not surprising. So I will have to trim about .070 to .080 off those shims to get to the final position. The seal strips are also pretty close so I may need to trim those a bit also.

Sunday Apr 8

Back to work on the canopy release mechanism. I finished slotting the short link. It is 1/8 inch wide on the left for the hinge pin (bolt) and .060 on the right for the crank. Here I assembled the short link to see if it moved smoothly. It did after a little work with the jeweler’s file.

The rest of the time today was spent preparing and priming a batch of parts including the angle and plates for mounting the vertical stabilizer and parts of the canopy release mechanisms. I also primed and painted the F-704K upright cap strips.

Aft Canopy Latch – 2 hrs

April 2, 2012 Leave a comment

Monday Apr 2, 2012

Tonight I started working on the aft canopy latch bar installation. It began with marking the upper hole locations on the C-611 UHMW blocks. The instructions conflict with the drawing notes in this area. The drawing says to mark and drill the top hole, but the instructions say to mark the vertical locations and clamp the latch bar assembly onto the F-705 bulkhead and drill shallow holes in the UHMW blocks using the F-705 holes as guides. I compromised. I marked the upper hole locations and clamped the latch bar assembly onto the F-705 bulkhead to visually check that the holes where going to align. I found that I had to adjust the spacing between the blocks a little to align them with the holes in the horizontal direction. They aligned fine in the vertical direction. Here is a photo of the blocks with the upper hole locations marked.

Satisfied, I drilled the upper holes in the UHMW blocks using a #10 drill then enlarged the upper holes in the F-705 bulkhead using a #12. That allowed me to install the latch bar assembly with the upper bolts as shown below.

Then I drilled shallow holes into the UHMW blocks with a #30 drill from the far side using the F-705 bulkhead holes as the guide. I then removed the latch bar assembly and finished drilling the lower holes on the drill press using a #10 drill. I enlarged the lower holes in the bulkhead using a #12 drill. While I had the latch bar out I marked it to remove the lower horn on the right side which is not needed. Here it is marked.

And here it is after I cut off the horn and smoothed it on the belt sander.

Then I put it all back in the fuselage. This is a close-up.

And this is the overall bar view. I noticed that the rotation has a lot of drag due to the tightness of the bar in the bearings. I’m going to check the forums on this. Next I took the bar back out and applied touch-up paint to the areas I sanded.