I finished applying RTV around all of the junctions between the baffles and engine. Here’s the forward end just behind the propeller.
This was one of the wider gaps between the baffles and engine. I partially filled it yesterday to provide some support to allow the RTV to fill the gap.
Getting around the edges of the inter-cylinder baffles was a real pain. I had to apply the RTV with a long aluminum rod. I could reach this part by reaching down through the cylinders from the top, but the rest required reaching from the bottom around the intake and exhaust pipes, oil return lines, wires, cables, etc. This isn’t the prettiest application, but it should be air tight.
The propeller control line wasn’t quite sealed by the grommet, so I had to apply a small dab of RTV to fill the gap. I really hope I don’t have to take off these baffles for a really long time.
I had planned on removing the propeller for a while since it’s really in the way while wrapping up the plane. Doing this solo is kind of a pain, but can be done. With this out of the way, I can walk from one side of the plane to the other with the garage door down. It’s also going to make applying the rest of the RTV around the forward end of the baffles substantially easier.
Over the last couple of days, I filled, sanded and primed the top of the plenum. After some minor sanding, this is ready for the top coat of paint that matches the baffles.
Well, the battery was dead again today. I’ve known what the problem is, but I haven’t decided what to do about it. When I was first putting together the electrical system design, I decided that I wanted the interior lights to work even if the battery master was off to help with baggage loading, boarding, etc. Later, when I settled on the dual color light and dimmer, the design required running power to the dimmer first, and then to the color selection switch and then the lights. I didn’t realize until the entire system was wired up that the dimmer leaks about 43mA even with the lights off. With a 17AH battery, that leakage current effectively drains the battery in about two weeks. I kept putting it off hoping I could find a way to preserve the behavior, but fix the current leak. I ended up deciding to just move the cabin lights to the interior light circuit on the VP-X. After doing that, my leakage current is now well less than 1mA which is more than acceptable.
I also mixed up some epoxy primer and painted the underside of the plenum.
I haven’t worked on the plane in a bit because I’ve been laid up with the flu. Now I’m fine but Jenn and the kids have it, so I headed out to the garage after everyone went to bed early. I used some contact cement to bond the cowl inlet seals to the mounting strips. I only took a picture of the lower left one, but all four are done.
Next, I mixed up some epoxy/micro and filled the weave and low spots on the plenum.
I had a little extra, so I put a little more on the upper cowl to fair out the area below the oil door in order to match the curvature.
The high-temp epoxy that I used on the plenum needs to be post-cured in order to withstand the high temperatures it will be exposed to after engine shutdown. I took it down to the Tech Shop and used their large powder coating over to cure it at 150º for three hours. The heat substantially softened it and it flattened out a bit in the oven. After I brought it home, it didn’t really fit the baffles correctly and would have cracked if I tried to force it into position. I set up my space heater over each side and heated the plenum past 150º and it softened right up. I then pushed it into position and screwed it down. This worked beautifully, and the plenum now fits the baffles really well.
I finished trimming around the edge and then sanded the plenum flush with the baffles. I still need to sand and fill the plenum in preparation for paint, but I think the fabrication is finally done.
I finished trimmed the front edge of the plenum so that it’s flush with the baffles, then reinstalled it on the plane. I then reinstalled the cowl and began fitting the upper cowl inlet seals. We’ve been having a cold snap here, so it became too uncomfortable to work in the garage with the door open, so I called it an early night.
No pictures tonight, but I sanded the filler I applied to the plenum and then marked all the way around the edge to trim it flush with the baffles. I did part of the trimming, but I think I’m going to try and fully cure the plenum before finishing.
A year or two ago, I became aware of an issue with the stock ECI pushrod shroud retainers. These were made of heat treated carbon steel, and suffered from hydrogen embrittlement due to a manufacturing issue. There have been a few instances of these breaking in service which causes the pushrod shroud to push out from the crankcase leading to a loss of engine oil.
I had been planning on replacing these with Lycoming parts before my first flight, but ECI recently issued Service Bulletin 12-1 acknowledging the issue and offering free replacement parts. I got the kit in the mail today and replaced all of the retainers. Here’s the old one that I pulled out of the engine. These are 0.032″ thick.
Here’s one of the new ones installed. These are 0.040″ thick stainless that is not susceptible to hydrogen embrittlement. The nuts are torqued to 96 in-lbs and then the safety clips are bent up to prevent the nut from turning.
I drilled a hole in the side of the fuselage skin for the canopy latch lock. Getting this hole positioned correctly required numerous measurements and calculations to ensure that the lock wouldn’t interfere with any part of the latch.
I fabricated a 0.063″ doubler plate to position the lock so that the face is flush with the skin. The plate will be centered over the hole, so I added some layout marks to help center it.
After drilling the plate to the skin and drilling out for the lock, I installed everything to see how well it lines up. The lock is almost perfectly flush with the skin.
Next, I needed to mill out the slot for the cam. I headed to the Tech Shop and quickly milled out a slot in the lower mounting angle.
I then milled out a corresponding slot in the latch handle.
The cam is only about 0.080″ thick, but my smallest mill was 3/16″. Because of this, I had to offset the slots so that the cam would just fit.
After reinstalling the components in the plane, I tested it out and everything works perfectly. Here’s the latch in the unlocked state.
And here’s the locked state. With the latch locked, the handle is completely immobilized. I’m super happy with how this turned out. Everything about the latch and lock is flush with the fuselage skin. I’m sure I’ve picked up a huge amount of speed without the handle and cam lock sticking out from the fuselage :-).