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.

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.

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.

Today we continued working on the cowling and the exhaust system.

While Dad handled the sanding and fitting of the cowling, I worked on setting up the exhaust system. First I assembled the support clamps, then applied anti-seize lubricant to the sleeve and ball fittings, then set it up underneath the engine.

With dad’s help we were able to mount the pipes onto the cylinders, doing up the hardware finger tight.

Using a roll of 3/4 inch electrical tape, I set the spacing correctly and installed the support clamps on the aft edge.

Dad did another round of filling today, as there is still a ways to go to achieve the alignment we need on the cowling air inlets. It’s amazing to watch him work, knowing just what’s needed to get the perfect fit and finish. At 79 years old he’s still putting in very long days, with no complaints.

With my dad back in town and helping with the cowling again, we made progress today on a few fronts. Dad worked on installing the top cowl air ramps, and started on the oil door, while I focused on the exhaust system.

Before the air ramps could be installed, we needed to address the alignment issues with the front of the cowling. In a couple of sessions, Dad applied filler to the edges of the air inlets, and trimmed the air ramps to fit.

Meanwhile, I installed the first section of the heating system, the heat t-fitting. I left the clamps loose for now, as it’s hard to tell if this will need to be finessed into position later. I then drilled out a couple of rivets, and installed the FF-00084 cover. After some puzzling, I realized that this stops the hot air from escaping the system when the passenger vent is closed, and the pilot vent is open.

We then found and trimmed parts for the oil door.