Scott & Tanya Card RV9A build log (N4822C)

I’ve been flying like crazy since I got the ignitions replaced. I now have 10 hours on the new ignitions and loving every minute of it. I did a couple of 1.5hr flights with friends that are currently building RVs that had not received the full intro yet. They both commented about the “launch” feeling on takeoff with the healthy constant speed prop and the fact that my demonstration of all the goodies in the panel will probably cause their wallets to become lighter on their build. I had a ball. Thanks guys for providing ballast.

On Christmas day, Tanya and I (Tanya was PIC the whole flight) flew out to Brenham just because the weather was so great. It was a ghost town out there, but we didn’t care. It was a nice flight.

I went for a quick night flight over to Llano. It was just a little bumpy but not too bad. On my way back home at 5500′, a meteor or something reentered the atmosphere right above and ahead of me. It was super bright on a very clear early night sky. It scared the crap out of me for a second. Wow! That was a big first for me.

Ahh, there is always another test to do. I live for it.
I have long been battling a “prop surging” issue. I have concluded that there were a number of variables contributing to the symptoms which are now resolved. The first thing was that I had an MT prop governor that was known to have a tendency to surge. I sent it back to MT for update and still had the problem. I quickly abandoned the newly updated prop governor for a new PCU5000X which is known to be of very high quality.
Through testing the new prop governor, I found that I had some pretty severe prop surging (-+ 120rpm or more) on takeoff, only with high, 195+ deg oil temperatures. The surging would only happen on initial climbout with high oil temps and the symptoms would begin with a significant rpm drop of 100rpm or so. Then the prop would recover to the set point or slightly over shoot it. This would occur a time or two then settle down. I was convinced that the prop governor or the prop wasn’t quite doing its job when the oil got hotter and thinner. I’ve been using Exxon Elite 20w50 oil. I had the PCU governor back at American Propeller twice. They declared it was fine. The second time, I also sent along the MT governor for reference at their request. They ran the revised MT governor and found that it still had a surging problem on the test bench. It currently sits on my shelf.
A lot of this testing occurred in hot summer OAT. It was suggested that maybe I was experiencing a hot fuel problem. Ok, maybe. I have a blast tube on my fuel pump and all of my fuel lines are in fire sleeve FWF. Enter much cooler ambient temps. I did some temp instrumentation of and around the fuel pump, lines, and gascolator. No way this was a fuel problem. Now with the lower ambient temps, I was having no prop surging problems “because” oil temps were way down. I was just enjoying flying for a while.
I’m not one to let a problem go unresolved so I used the opportunity with lower OAT to isolate the oil temps. I started slowly blocking off the oil cooler as one would do in cooler weather. No prop surging. Over the course of a few flights I added tape to get the oil temps up to the 195-200 deg range. The prop surging returns. Tanya and I were doing laps in the pattern one day as the oil temp got into that range.
This is when we had our last P-mag failure! We had been running for about 15min with oil temp at about 198 when we noticed the ignition had failed on a full stop, taxi back, and runup. I’ve written the story of the rest of this flight previously. The short version is that we restarted the ignition and did one more lap with the ignition failing on initial climb with the obvious demonstration that the ignition failing felt exactly like the beginning of our prop surging issue, except with only one cycle. Note, oil temp at about 198 and everything else very cool due to low OAT and lots of blast tubes.

So back to the most recent test. Ever since then I had been itching to do the same test with the new ignitions. OAT was still very cool and I brought the oil temp up. Lap after lap in the pattern with the oil temp 200-210 degrees and no prop surging. Nothing but perfectly smooth power. We “almost” always had “prop surging”, now recognized as power (yikes!), problems on initial climb when the oil temp was this high.

My clear conclusion is that early on I did have a real prop surging problem with the MT prop governor. After that was resolved with a new governor, similar symptoms continued due not to the prop governor but because of intermittent ignition causing variable power in the condition of high power and high oil temperatures on the nose of the P-mags. Critical to these conclusions are the opportunities afforded by the change of season with cooler temperatures in order to prove the condition with artificially increased oil temp only. In the end, I think I was able to fail the P-mags almost at will with oil temp and power setting hence my comments that those cooling fins on the newer 114 model P-mags are probably more important than many people realize.

I am very pleased to finally have resolution to a number of problems all at once with replacing the P-mags with a normal Slick magneto and Lightspeed Plasma II+.

Time for an oil change. I’ve been changing the oil every 25hrs. This is the 100hr oil change. So, with my new whiz-bang ignition setup, I went out after work and launched into the darkness. A few laps around the practice area, played shoot-down-the-bogie with the TIS on the 430W. This equates to finding an unsuspecting target and maneuvering for closure from behind. Don’t worry, I’m talking no closer than about 8mi. before breaking off… Then I headed down toward town for a couple of passes over the neighborhood while in contact with Austin Approach. Then I headed back to GTU to start that oil change. Not too bad for 35min of warming up the oil.
Back at the hangar, I quickly pulled the cowl and began the oil drain and left it that way until the next day.

The following day I went out to finish the oil change. I had the oil filter changed, re safetied, and new oil added in about 8 minutes. No mess. I have this down pat now. The key is a ziploc freezer bag under the filter angle adapter to catch the mess. With the new engine, I’ve been having to stay on top of keeping hose clamps tight. The clamps don’t loosen but the hoses compress a little and the clamp needs to be tightened up. I’m mainly talking about the oil return tubes where they attach to the case and the intake tubes. They were all in need of another turn or so.
I’ve also noticed a little fuel staining around the #2 intake tube at the cylinder manifold. I’ve been checking engine bolt torque on the manifolds and various other parts as things wear in, so the bolts were tight. I decided to pull the intake tube and see what was up. What I found was that some of the inside edge of the gasket had begun to deteriorate. It had also picked up some of the paint that was on the intake tube which looked like it effected the seal. A new gasket will be ordered for proper resolution. Until then, I reassembled with a little “extra” gasket dressing per advise by Mahlon. When I went to reinstall the intake bolts, they were very tight after 4-5 threads. Enough for concern and further analysis. I concluded that there was some kind of aggregate from the manufacturing process in the cylinder threads. Almost like silver sand. I very carefully used a tap to clean out the threads and all was well.
Finally, on our last flight, Tanya said we HAD to have more heat, so I opened up the heat duct on the rear baffle a little more. I had it about 85% blocked by foil tape so I removed some of that so it is about half open. I also put a little more tape over the oil cooler while I was in there. Note that these two operations required removing the plenum top. Kind of a pain with so many screws.

I’m ready to cowl it up and giddyup again!

The weather was severe clear and 55 degrees. I did an hour flight, mostly orbiting the field. I got up the nerve to do a mag check in flight. That is a first for me. Yep, the mag check while motoring along at 140 kts behaves the same as on the runup pad. The engine is very happy with this ignition combination so far. I put a couple of hours on it and Tanya went for a ride late in the day. She even commented on how it seemed smoother. I’m very happy with the new ignition setup.