Replaced Heater Valve

I recently noticed that my cabin heat wasn’t working. After a quick inspection, I realized the control arm on the heater valve had broken off of the flapper valve. The valve is a stainless steel unit from Plane Innovations which I upgraded to because I wanted to keep all steel components on the firewall.  I emailed the company about the best way to repair the valve and they rushed out a new one free of charge. I wish more companies had this kind of customer service.

Unfortunately, getting the old valve out requires pulling a substantial amount of the interior out. The heater valve is behind the tunnel cover which is under the fuel pump cover. The fuel pump cover sits under the forward seat pans, so the seats and carpets need to be removed.

My son helped me remove the nuts holding on the heater valve. This is one of the few items that regrettably I didn’t attach to the firewall with nutplates. It would have made replacing it far easier. Unfortunately, adding nutplates now is virtually impossible, so we just bolted the new one on the same way.

Here’s the failed heater valve. The spot welds simply failed due to the high vibration around the firewall. The new valve has five spot welds instead of four, but I’m not optimistic this will prevent this from happening again.

Broken Exhaust Support

While taxiing in from a flight, I heard an odd clunk. I took off the cowling to do a careful inspection and found that both exhaust supports cracked all the way through right at the bend. Squeezing this tubing flat and then bending it clearly put too much stress in the metal.

The bottom of the support just has a flattened piece of stainless steel tubing bolted to a bent piece of mild steel. The mild steel is much tougher and can withstand the vibration without cracking.

I replicated this arrangement at the other end of the supports.  Fortunately, it was a pretty quick fix and this should be much more durable.

Modified Breather Vacuum Valve

There is a thread on Van’s Air Force about carbon build up in the breather tube.  I pulled the tube off and there was some build up (maybe 10% of the cross-sectional area of the tube).  Most could be easily removed with a pick, but I used a wire brush to get the inside of the tube totally clean.  Here are all of the carbon bits that came out of the tube.

If this tube were to totally close off due to carbon buildup, it could pressurize the crankcase and blow out the front oil seal.  To prevent this, I put a T in the breather line and ran that to a second vacuum valve positioned above the exhaust pipe to burn off any oil that might drip out.

Fabricated New Exhaust Support and Replaced CHT Probe

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.

Fabricated New Exhaust Support Brackets

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.

Restored Airplane to Flight Status

Since I had the aft baggage wall out to adjust the ADAHRS, I took the opportunity to inspect all of the elevator linkages and relubricate them.  I then vacuumed out the entire fuselage.  Despite doing this thoroughly before first flight, there was an amazing amount of debris including a large number of small metal particles from the drilling operation when assembling the fuselage.  I have no idea where these particles were hiding when I earlier cleaned out the fuselage.  I then reinstalled the aft baggage wall and all of the interior.

Before reinstalling the cowl, I adjusted the prop RPM again to hopefully get pretty close to 2700 RPM.  I also wrapped the fuel flow sensor with some extra thick fire sleeve and some safety wire.  It’s not the prettiest wrap job, but I’ll redo it if works.

SkyView Battery Test, Bowden Clamps and Fuel Filter Servicing

I previously sent the backup battery from my left SkyView screen into Dynon because it didn’t seem to be charging during the first few flights.  They charged the battery and tested it and it was fine.  They sent it back to me so I installed it tonight and ran the battery test on both screens.  Both passed by powering the screens for 45 minutes (and new batteries should power the screens for more than 1 hour).

While the battery test was running, I replaced a couple of cable clamps in the engine compartment with non-cushion bowden clamps that hold the cable much more securely than the cushion clamps I was using before.  This is the clamp for the oil cooler butterfly control cable.

I also replaced the cable clamp at the forward end of the alternate air door control cable.

Finally, I decided to pull and clean the fuel filter again.  There was a surprising amount of gunk in the filter.  Most of the volume was some sort of fuzzy material, but there was also a lot of dust and even one small metal particle.  I redid the safety wire and installed it back in the airplane.

Finished Oil Change and RAM Mounts

I wrapped up the oil change by installing a steel cap that Greg gave me to replace the aluminum one that I previously had installed.  I installed and torqued it down in order to mark where to drill for safety wire, then removed and drilled it.  I now no longer have any aluminum fittings anywhere forward of the firewall containing flammable liquids (oil, fuel and brake fluid).  I then filled the engine with oil.

While I had the interior out, I decided to install a couple of RAM ball mounts.  While the upper side panels were still in place, I marked and drilled through them and the upper channel here.  I then removed the upper side panels and installed some NAS1329A08K75 rivnuts.

I reinstalled the upper side panels and then attached the RAM ball mounts.  Here’s the one on the passenger’s side.

Here’s the one on the left side.

I’ve been flying with an iPad mini for ForeFlight since I like it as a nav backup and I keep my POH, avionics owner’s manuals, etc. in there.  I was just laying it on the seat, but that’s a pain when I want to do some acro.  Mounting it should keep it handy but also keep it from flying around the cockpit when inverted.

Oil Change

After letting the oil drain completely from the engine overnight, I pulled the oil filter and oil screen.  I really need to figure out a less messy way to pull the filter as I spent more time cleaning up spilled oil than actually removing the filter.

I also pulled the drain cap off of the low point at the oil cooler.  I captured some of this in a cup to get an idea how much oil is in here.  I’m guessing it’s at least half a quart.

Here’s the oil screen.  I’ve heard it’s not uncommon to find some carbon particles in here, but mine was clean as a whistle.

I reinstalled the screen with a new crush washer and safety wired it shut.  I’m really happy with how easy it is to access all of the parts of the engine necessary for an oil change.

Firewall Forward Inspection and Flight Testing

I got down to the airport really early this morning because I wanted to take care of a couple of things and get some flight time before heading back to Hollister to help Greg.  I pulled the cowl and gave everything a thorough inspection.  One of the things I found was that the oil filler tube could be rotated a little bit by hand.  Since the safety wire hadn’t moved, I think the fiber washer just compressed a bit.  I used a wrench to snug the tube back down and then redid the safety wire to keep it tight.

I also adjusted the high RPM stop on the governor 1 full turn to increase the maximum RPM a bit.  I’ve only been seeing a little over 2600 RPM at the stop.  Although I’ll likely have to adjust it further, I redid the safety wire to ensure this can’t move.

I buttoned everything back up and took off again.  I figured I could get at least an hour of flight time before landing at Hollister again.  I decided to shoot an instrument approach to get some more experience with the autopilot and interaction between the GTN and the SkyView.  I loaded up the GPS 31 approach at CVH with the RUDNY transition and engaged the autopilot.  I duplicated the approach waypoints in the SkyView since they don’t yet automatically stay in sync with the GTN (though this is coming).  The GTN did turn anticipation and smoothly guided the autopilot onto the initial leg of the transition.  I programmed an altitude step-down and commanded a 500 fpm descent.  The autopilot turned smoothly to intercept the final approach course and held the descent rate rock solid.  I broke off the approach a couple of miles out and climbed back up to 6,000 ft.

I headed over to the acro practice area and did a couple of rolls to warm up.  I then tried a loop for the first time.  The plane really builds speed fast on the down line, but pulling some G’s takes care of that nicely.  Next, I tried a hammerhead on about an 80º upline to keep some positive G on the engine for oil pressure.  The rudder is quite a bit more powerful than anything I’ve flown before, so the rotation at the top was crisp and quick.

Finally, I decided to do a few spins to learn how the plane recovers.  The plan was to start with an incipient spin entry with an immediate recovery.  I climbed up to 8,000 ft and positioned myself near the South County airport in case I needed it.  I pulled the power smoothly back to idle and started slowing up.  Right at the stall break, I fed in full left rudder and the plane rolled about 90º to the left and the engine stopped cold.  The prop came to an immediate stop straight up.  I had already initiated the spin recovery and I immediately rolled level and got the nose down into a glide.

One of the questions Dave Morss asked me to determine if I was ready for flight testing was how I reacted in an emergency situation.  I’ve only had a couple of surprises in my years of flying, but I knew that I tend to remain calm and work the problem.  When the prop stopped, my only reaction was to utter the word “interesting”.  After establishing the glide, I hit the engine start button and got the propeller windmilling again, but the engine still wasn’t producing power.  I still had the mixture pulled way out, so I opened the throttle to give the engine some more air.  After a few seconds, the power came back smoothly.  I climbed back up and decided to try again, but this time over Hollister since they have much bigger runways in case I couldn’t get the engine started again.

After arriving over the airport, I again pulled the power to idle and started to slow up.  I slowed more gradually this time so that I could monitor the engine more closely.  As the plane slowed, the engine RPM slowly dropped.  When it got down to around 400 RPM, I knew something was wrong and I added power back.  The engine stumbled a bit as the power came back up, but it ran smoothly again at around 75% power.  I pulled back to around 40-50% power and the engine started running rough again.  I brought the power back in and started examining the engine monitor more closely.  My EGTs were down a bit, so I decided to try leaning the engine further and repeating the approach to stall.  This time, the RPM held steady at about 700 RPM all the way through the stall break.  I didn’t repeat the spin entry, but I feel comfortable now that the problem was simply an over rich mixture for the altitude.

I landed at Hollister to help Greg with his RV again.  It took much longer than we expected, but we were able to wrap up all of the spar bolts and get the nuts torqued.  The ailerons and flaps still need to be hooked up, but other than that, the plane looks pretty close to being ready for inspection.

I knew I was pretty close to empty on the left tank, but I wanted to run it dry on the flight back, so I left a little early to ensure I would have sufficient light.  I ended up flying for nearly 20 minutes before the tank ran dry.  I then switched to the right tank and landed at South County.