Tonight I installed the Cylinder Heat Temperature (CHT) probes. These screw into ports near the cylinder heads and measure temperatures. I used some copper-based anti-seize on the threads before installing.
CHT Probes
EGT probes
Tonight I installed the Exhaust Gas Temperature (EGT) probes. Despite the instructions claiming they would fit snuggly in a reamed #30 hole, there was no way that was happening. After unsuccessful attempts to install, using calipers, I could tell I’d need to go up a couple of drill sizes. I think I ended up drilling #28 holes, and then I was able to get the probe through. The fit was still fairly tight, so hopefully these won’t leak gasses.
Test fitting cowling
Today we test fit the cowling, just a couple of hours before my parents headed off. The fit was much better and easier than I anticipated, but there was still something not quite sitting right. Later in the day I came back to troubleshoot and found one baffle seal that had flipped and was holding the two halves of the cowling apart. With that fixed, I was able to safely install all 4 of the screws around the air inlets.
Oil Door, Gear Leg Fairing, JDAir Latch
Today we installed the oil door, and I riveted on the canopy latch bottom bracket. We also started on the gear leg fairing.
Oil Door, Cowling, Exhaust
Today we worked on the oil door, more sanding on the cowling, and the exhaust system.
After a lot of sanding and filling and sanding and filling, the cowling is basically done. In addition to all the sanding, Dad drilled holes, countersunk them, and installed nut plates while I supervised and learned. The inlets are nicely aligned now, and the baffle seals around the inlets are installed and ready to be test-fit. I’m curious to see how the bottom cowl will fit, as there is almost no room to maneuver behind the spinner plate. Hopefully we’ll get a chance to try to fit the whole thing together before mum and dad leave town.
We have also been working on the oil door, and have the nut plates installed on the top cowling. I primed the aluminum parts before wrapping it up for the day.
Baffling & Exhaust
The air ramps looked good this morning, and Dad got busy sanding them flush. Once the sanding was completed, he added a few strips of glass to strengthen the air inlets, particularly on the inside edge of the outboard sides of the air inlets. A lot of the glass layers in this area have been sanded away in the process of fairing the inlet opening.
In parallel, I continued working on the exhaust system, finishing the heat muffs and connecting the various cabin heat components with scat tubing. I trimmed a little bit off one end of one section of hose, but everything else fit perfectly.
Baffle Clamp Strips & Exhaust
Tonight I worked on installing the heat muffs. There are two of these muffs, arranged in series, that use exhaust heat to warm air which is then directed to the cabin warm are vents. The muffs are made up of sleeves that slip over the exhaust pipes, with end caps on each end. The end caps are held in place by two rods, which are safety-wired onto the exhaust pipe. The sleeves are held onto the end caps by hose clamps.
My first problem was that I had tried to outsmart the plans by putting the sleeves onto the pipes before they were mounted to the engine. Unfortunately one of the sleeves had flipped around, and I couldn’t reposition it without taking off the exhaust pipes. This was annoying, but not too much trouble. Going back to the step-by-step instructions, I installed the end caps and then called it a night.
Meanwhile dad was busy with more sanding and filling around the top cowl air inlets, and getting the air ramps to fit just right. Once the air ramps were close enough we glassed them into position. Because the engine baffle seals are already installed, we had to carefully position the clecos holding the air ramps into position so they wouldn’t interfere with the baffle seals when we installed the top cowling. Having the top cowl in position while the glue sets around these air ramps is important to ensure nothing is pushed out of alignment. We also draped a plastic sheet over the whole engine to catch any resin drips.
Baffle Clamp Strips
Today we removed the baffle clamps, and checked the filler had set correctly. It all looks good!
Baffle Clamps, air ramps, & JDAir Latch
Today I worked on fitting the JDAir latch mechanism into the slot, including installing the “dummy” rivets which only fill the existing holes and don’t clamp anything together. One of these rivets interferes with the latch, so a countersink is needed on the latch mechanism to work around it. With the countersinking done, I was able to fit the bottom bracket, and match drill the new rivet holes into the fuselage. Once I cleaned up the holes, I dimpled using a pop rivet dimple die. They never dimple very well, but there’s not much I can do.
Meanwhile, Dad worked on sanding and fitting the air ramps to the top cowl. These are basically ready to be epoxied into position now.
We also shaped the air inlet baffle seal clamps. Once these are bent to shape, they are wrapped in packing tape, and filler is applied to the inside edge of the cowling air inlet. The clamps are then used to form the correct shape. We did that, and will let it set overnight.
JDAir Latch
Tonight I started working on replacing the Vans canopy latch with the JDAir latch. Originally I wasn’t going to do this, because it requires cutting a larger slot in the side of the fuselage, and I didn’t want to risk it. Additionally, a lot of the 3rd party side panels are only designed for the standard latch.
At some point over the last year or two, Classic Aero started selling side panels that fit the JDAir latch. Looking at the actual modifications needed, and how much more solid of a latch it is, I decided to go ahead and change it out.
I downloaded and printed the instructions, checked the dimensions, then taped the template to the fuselage. Step 1 is to drill out the rivets holding the bottom bracket in place. This was easy enough. Then I drilled holes in the corners of each area which needs to be enlarged, and then used a small Dremel tool with a cutting wheel to complete the cut.
Next I’ll need to file the edges to a nice, flat, smooth surface, but I’m relieved to have gotten the scary step done without any collateral damage.
