Month: August 2024

This week I chipped away at the baffle tension rods over a series of evenings. I didn’t actually have a die for cutting the threads, so I had to order one from Aircraft Spruce. These were fairly easy to make, and came out looking good. Some more practice with cutting threads might have helped, but I got the hang of it pretty quickly. When bending the rods I used a block of wood with a slot cut in it to stop the rod rotating, which allowed me to bend both ends of the rods in the same axis.

Installing the rods was fairly easy. I cut a few lengths of 1/4 inch tubing to help prevent chaffing, although there weren’t many areas where interference is possible. Once I had the tubing slid over the rods and positioned correctly, I used some RTV to bond the tubing onto the rod.

With new crush washers in hand I also took time to install the remaining baffle hardware, and torqued everything.

Today I spent time adjusting the front baffles to fit nicely against the engine case. The front left baffle took the most adjusting, and after several iterations I was happy with the fit.

With the baffles fitting nicely I went ahead and installed the hardware and torqued everything up. I have run out of -40 star washers, so I ordered some more and put tape on the screws that were missing washers.

Tonight I test fit the front baffles. The front right baffle was the easiest to install, and looks to be a good fit. The front left was more challenging, but after disconnecting the oil return line, I was able to get it into position. This one will need a little adjustment to properly conform to the engine casing, and a couple of corners that need some easing.

In the process of test fitting the front baffles I noticed that I had made an error with the front center bracket. Just like the aft bracket, I had misread the drawing and had it on the left side instead of the right side of the centerline. Then I noticed I had the bolt installed from left to right, instead of right to left, on both brackets. It’s probably not a big deal, but it always makes me nervous when I miss something or find an error. What else did I miss?

I fixed the errors with the bracket, installed the hardware and torqued the nuts.

Over the last few evenings I’ve made a little progress on the front baffling.

I riveted together the parts, and applied RTV where instructed. The RTV strips are to reduce chaffing on the engine cylinder cooling fins. RTV is also used to help glue the mesh in place covering the cabin hot air intake.

These are ready to be test-fit onto the engine and trimmed (if necessary).

Tonight I worked on the front baffles, including the air ramp. Dad had already made progress drilling and deburring parts, and installing nut plates. I picked up where he left off and completed a page of steps.

Today I installed the aft baffles on the engine. I started by picking up some high temp RTV from AutoZone. The RTV is used to provided a cushion for the baffling where it will vibrate against the engine. I masked up the aft baffling, roughed it up with sandpaper, cleaned it, and then smeared RTV in the specified locations. This was then left to dry for a few hours.

Later in the day I installed the aft baffles, and looked to areas where it was rubbing against the case. I found a few locations, and marked them with a sharpie. Then I uninstalled it all, filed down the offending areas, and then reinstalled for (hopefully) the final time.

Tonight I test fit the aft baffling on the engine.

I found a couple of rivets that I had forgotten to set, so I went ahead and tried the aft baffling on the engine, and then took it off and set those rivets.

Trying the baffling on the engine was a little tricky. The instructions say to remove the oil return line from cylinder 3 to make it easier to install the right baffle. I can see why, it definitely gets in the way. But instead of undoing the fitting, just a gentle bend as it’s going on solves the problem. The much harder issue is the aft left baffle. It took me almost 30 minutes of trial and error to finally find a way to get it in. The trick is to insert it at about 45 degrees, getting the baffle under the engine mount bolt, then working it down into position. It also helps to angle it slightly forward.

I scratched a lot of engine paint off, and scratched the baffles, but was able to get them into position.

That’s when I realized another issue. I had installed the bracket on the wrong side of the case, and the holes were not even close to lining up.

I took it all off again… will fix it tomorrow.

Tonight I continued working on the baffling. I had to drill out a few rivets and redo them, as they had tipped over too much. I also found a mistake where I’d used the wrong nut plates, so I replaced those.

With the riveting done, I installed the fittings on the top of the engine case. These help hold the baffling in place. I had to gently bend the fuel line out of the way to ensure enough clearance from the bracket.