Chapter 22 – Duct Valves

As far as building, today was one of those kluge days from hell….

I’m still not feeling 100%… it’s really hot here… and unexpected mishaps have reared their ugly heads again: specifically, on the heat exchanger upper inlet duct heat restrictor butterfly valve.  As you can see below, I have the butterfly valve on top with the 2 drilled holes (I finished the 2nd one tonight), then the first stainless steel rod which proved virtually impossible to drill, then at the bottom the converted drift pin that I handily snapped off the 4-40 tap in the second and last hole . . . After repeated attempts to remove the snapped off tap piece, including knocking it out from the opposite side with a hammer, I was left with only a bent, misaligned butterly valve rod.

So I digressed and did a fair amount of research on different components and upcoming build tasks.  I then went out and picked up another 4-40 tap set and a couple of large grommets.  Upon returning home, I tested out a grommet in the fresh-cool/heat air transfer vent hole.  Amazingly, in light of the total SNAFU with tapping the butterfly valve rod above, the grommet fit in the odd shaped hole perfectly!

Below is another shot of the grommet more from the side.  You may note that I cut the grommet to taper down towards the top side (left in pic) and then sanded it to smooth it out flat.

I then drew up a cardboard template for the actual fresh-cool/heat air valve plate and then transferred that over to a piece of 1/16″ 2024 aluminum, which I then cut out.  The valve plate is curved on the top left corner to seal asl best possible with the PIC seat back corner.  It’s also curved on the lower right corner to seal up that curved corner as well.

Here is the fresh-cool/heat air valve plate and the rubber vent hole grommet from the opposite (inboard) side.  In the center of the valve plate showing here is where the valve actuation control arm will get mounted.  This will be the control arm that when the lever is moved forward or aft at the pilot’s station, the fresh-cool/heat air valve will be opened or closed for either cockpit cool ventilation air or cockpit heat.

Tomorrow I’ll try to regroup and get much more accomplished, including version 3 of the upper inlet duct heat restrictor butterfly valve rod.

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