Flying Update

I have found that the engine is running a little less smooth than I think it should. This is a challenging problem, in part because it may be running just fine. I have a fair amount of experience in single-engine piston airplanes, but most of it is not in recent times. At idle, I hear an occasional miss, even with the mixture leaned. The other day, I took off with the intent to fly for a few hours, but at 2500 RPM and full throttle, it was running rough enough to make me turn back towards the airport. To be fair, I’m not sure if a non-pilot passenger would have noticed it. I leaned the mixture a little bit and the roughness went away, but this didn’t make sense, because it was exceptionally cold that day, and the density altitude was probably well below sea level. On another day I found 150 RPM drop during a ground mag check, when I turned off the left mag. I tried running the engine up a little bit and leaning aggressively, but had no change. I taxied back on the rough mag and hopped out to check the exhaust pipe temperatures. All except number 1 were around 350 degrees, while number 1 was more like 300. I swapped the bottom plug from that cylinder to the top, and tried another mag check. This time the drop was on the other mag, confirming that the plug was to blame. I replaced it with a spare that I had on hand and took off to conduct an inflight mag check, as described by Mike Busch.

His process involves using the EMS data logging, so I figured getting that started would be a good first step. I had noticed earlier that when I went to the data logging menu in the D180, instead of the usual choices of “on” and “off”, I had a message that said “Error 4.” With me not having the tools to address that problem right then, I took off anyway and conducted the check as Mike describes. I wrote down the EGT changes, but as he points out in his articles on the subject, that’s not really enough information. The good news is that during those checks, I didn’t get any significant roughness. The bad news is that I had some wacky EGT numbers. The cylinders were all fairly even when running ROP, but one was about 300 degrees lower when running LOP. I resolved to get the data logging working, then fly on another day to get more valuable numbers and see what’s going on. I never have installed the little blocking plates in front of the front two cylinders, since the Vans baffle kit instructions say to not install them unless you find that you need them. I have been reading reports from Husky owners that they get much better LOP operations with similar plates in place, because the cylinders run more similarly to each other. So that’s another avenue to explore.

To address the “Error 4” in the data logging menu, I did some Googling to find that it is a bug with the Dynon. Speculation is that the data log file becomes corrupted. The fix is for Dynon tech support to send a file, which I then send to the D180 as a “restore firmware backup.” The repair file is firmware version specific, and Mike at Tech support sent the version that corresponds with the latest firmware. I was due for an update anyway (though I didn’t realize it just then) so I downloaded the latest support program and went back out to the airport. I went through the usual ritual of powering off both the D180 and D100, then updating the HS34. Then I updated the D180, then the D100. After all of the firmware updates, the Error 4 message was still there, so I sent the repair file. The good news is that the new file fixed the problem, but the bad news is that there wasn’t any log file there. The D100 did have a good file though, and it has been extremely fascinating to study. Now I’m looking forward to getting to fly again and get some good data from the D180, which will be much more valuable, since it should have EMS data too.

In fact, with having so much information available in the logs, I think I’ll plan to redo the bootastrap glide tests, to try to provide better numbers for the data plate.