Fabricated New Exhaust Support and Replaced CHT Probe

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I needed to move the exhaust support tubes outward to clear the SCAT tubes going to the heat muff.  Sadly, I didn’t get any pictures while the cowl was off, so I tried to take some pictures of what I did through the openings in the cowl.  I replaced the aluminum bar that ties all four pipes together with one that is 4″ longer.  I drilled additional holes in each end to attach the clips that tie the stainless tubing to the bar.  This moves these supports out about 1 5/8″ on each side.

I rerouted both SCAT tubes and replaced the piece that was worn by rubbing on the exhaust support.  Now there is plenty of clearance all around.  This piece of tubing now runs above the lower engine mount tubing so it doesn’t rest against the wire going to the alternator.

It’s pretty tough to see here, but the SCAT tubing from the heat muff to the firewall valve now runs under the horizontal tubing on the engine mount.  This shortens the tubing and provides a more direct path into the heat muff.

I received a new CHT probe from Aircraft Spruce, so I installed it to see if the problem was the probe of the connection.  This probe works just fine, so I’m going to redo the connections on the other one to see if the problem comes back.

Fixed Fuel Flow Sensor

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I’ve always had a slightly erratic fuel flow.  The fire sleeve I added a couple of months ago helped, but didn’t fully resolve the problem.  Although I still suspected a heat problem, I called Dynon to get other ideas.  They sent me a document on diagnosing fuel flow issues and wanted me to remove the 90º elbow on the outlet before trying anything else.  I decided to call EI who makes the sensor to see what they thought and they told me that the number one cause of an erratic fuel flow sensor was a bad electrical connection to the sensor.

I pulled the heat shrink off of the knife splices for the three wires going to the sensor.  I re-crimped them and squeezed the splices so that they’re much tighter.  I then re-heat-shrinked them and took it up for a short flight.  The fuel flow was rock solid.

Update: with over 5 hours on the plane now since redoing the connections, I’m pretty sure this is now resolved.

First Flight Outside my Phase 1 Flight Test Area

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André was feeling better, so we decided to fly and meet my buddy Dan somewhere for lunch.  We flew up to the Nut Tree airport just north of the Travis Air Force Base.  It was a bumpy flight and André wasn’t feeling 100%, so we didn’t do any aggressive maneuvers.  After lunch, I gave Dan a quick ride and the tanked up with some cheap gas and headed back to South County with André.

First Passenger

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I was supposed to take my buddy André up as my first passenger since he helped so much with the build over the years, but he got sick.  After wrapping up the next exhaust supports, I needed to take the plane up for a test flight, so I took my nearly 11-year-old son Matthew up instead.  He was a little nervous, but ended up really enjoying the flight.  He asked to go upside down, so we did a couple of rolls.  He felt a little weird, so we didn’t do anymore and headed back to the airport.

Fabricated New Exhaust Support Brackets

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One of the things I’ve been needing to do is replace my exhaust supports.  I originally built them to the plans from Vetterman Exhaust which involved supporting them from the engine mount.  This puts stress on the exhaust as the engine shakes at startup and shutdown since the exhaust can’t move with the engine.  It’s better to support the exhaust from the sump so that it can move with the engine.  I ordered some 0.035″ wall thickness, 3/8″ OD stainless steel tubing and some MIL6000-6 rubber tubing which is the same as what came from Vetterman.  I cut the tubing to length and flattened each end so I could drill holes and bolt it to the sump and exhaust support.  There is about 1/4″ gap between the upper and lower tube, and I put a small flare in the end to keep the tubing from pulling out.  Here’s the lower end of the left support.

You can see the upper end has a bend to align with the sump.

Here’s the left side.  This support runs tight against both pieces of SCAT tubing.  I’ll keep an eye on this for chafing.  If it does, I can fabricate a bracket to move the lower attach points outward and then reroute the forward SCAT tube so there is no interference.

Phase 1 Complete!

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I got up early this morning to wrap up my phase 1 flight test period.  Since I only needed one more hour, I didn’t have to get up quite as early as yesterday.  There was a 1700 ft overcast over the airport, but I found a hole and climbed through it.  I used the time to play around with the autopilot, testing editing flight plans, joining courses, etc.  After flying around for about 45 minutes, I descended through another hole and landed.  I taxied up to the hangar right as the hobbs meter rolled 40.0 hours.  I’m officially out of phase 1!

Almost Finished Phase 1

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I got up at 4 this morning so that I could be airborne right at daybreak.  I got nearly 5 hours in before making it to work at about the same time I normally do.  I’m now only 1 hour shy of my 40 test hours.

Early Morning Flight

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With Jenn needing to study all day, the only time I could fly was early.  I got up at 4:30 again and managed to get about 3.5 hours of flight time and still got home about the same time the kids got up.

One of the acro maneuvers I had not tried yet was spins with power.  At 7,000 ft, idle gave me about 5″ of manifold pressure, so I started with a spin and 10″ of manifold pressure.  The spin was faster and the nose came up slightly, but it was still very conventional.  I worked my way up in 5″ increments to full power (about 24″).  At full power, the spins have a much more pronounced hookup, and the rotation rate is impressive.  The nose also comes up quite a bit with that much prop wash over the tail driving it down.  It’s a fairly nauseating maneuver, so I don’t think I’ll be doing this with passengers.

Bird Strike

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I went out for another really early flight this morning.  I dropped into​ Hollister for some pattern work and hit a bird during the flare to land.  I was planning on just a touch and go, but I stopped on the ramp and shut down to see if there was any damage.  This is what I found.  I pulled it out along with a couple of feathers I could reach through the inlet.  The neck was nearly severed and was just hanging on with a few tendons.  Satisfied that there was no damage, I launched again and headed back to South County for further inspection.

When I pulled the cowl and plenum, there were feathers everywhere.  Here’s a small one that stuck to some of the sealant on the injector line.

There were a couple stuck in various places behind the engine.  This is one of the long wing feathers that somehow made it back here.

There were a bunch of feathers down between the cylinder fins and stuck against the heater muff screen.  I’m glad I put a screen here since these could have found their way into the cabin.

There were also a bunch on the screen going to the oil cooler.  Much easier to clean here than pulling the oil cooler plenum.  There were also a couple of blood stains that required a bit of cleaning.  Overall, it was probably on 10-15 minutes to get it all out and there was absolutely no damage.  It could have been much worse.