07.05.2021: I noticed during the last few flights that my engine is running hot when climbing at full power, with the CHT reaching the yellow temperature range even at cold outside temperatures. The oil temperature hower stays normal. When discussing this with the mechanic we concluded that it might come from the carburettors, which are due for overhaul anyway. So I did that overhaul today, with support from the mechanic as I always do when working on flight critical parts of the enginde of my plane.
One of the first steps to be done right after disassembling the carburettors is checking whether the floaters are below the maximum allowed weight of 7 g per pair, which both pairs were.
We then cleanded all parts and changed all seals and o-rings, and then reassembled them again. I then re-installed the carburettors, followed by the synchronisation. Once that was done I of course had to do a checkflight. In the morning when I did the overhaul we had pouring rain, but as predicted the weather cleared in the afternoon. We currently have a record number of flight students in our flying school, so I had to wait a bit to depart as our two Aquila two-seaters were busy doing touch-and-gos.
Due to airspace restrictions I had to fly towards the mountains to do my climb test, but they were partially in clouds. I decided to do a continuous climb at low speed and max power from around 3’000 ft to FL100, flying a sequence of S-curves to avoid the clouds. It seems that the problem is cured, as the CHT never even got near the yellow range, but it was fairly cold, with only 13 C in Lommis and -4 C at FL100. I will therefore repeat the climb test the next time I go flying at a higher ambient temperature.
Flying back I passed the Säntis, which was barely visible, with most of the mountain obsucred by patches of low clouds and the tip of the antenna of the transmitting station sticking into a thick overhead layer.
When flying back towards Lommis I could see the fresh snow, which has falled during the last two days down to below 4’500 ft. That snow will however disappear over the weekend, as a significant Föhn storm has been announced, blowing from the south across the alps. This should make the temperatures in Lommis climb from around 0 degrees in the night to arouund 28 degrees C on Sunday afternoon. While this temperature would be good for a second test flight, the accompanying turbulances probably won’t.
14.05.2021: I have considered for quite a while to replace the lead starter battery in my SportCruiser with a LiFe type battery, as the cheap motorcycle lead batteries I’m using typically only last three years. Towards their end of life I usually also have low voltage indications when landing with the engine on idle, which is annoying. And finally, a LiFe type battery is significantly lighter than a lead battery, giving me more useful load.
One of the other homebuilts in Lommis is already equipped with a Super-B Lithium Iron Phosphate (LiFePO4) Battery, and the owner is very happy with it. He installed it in 2014, and has never had any issues with it. Searching the internet for a Super-B vendor I found a small company nearby, which is specialised in developing autonomous power supplies for e.g. ambulances, recreational vehicles, boats and off-grid houses, e.g. in the mountains. By coincidence the had a Super B SB12V15P-EC in stock for a really good price, which is the one I was looking for, so I straight went to buy it. It has 15 Ah and weighs only 2.5 kg, compared to the 6.1 kg of the current Yuasa NPC 17-12 battery.
Today I went to install it, but for whatever reason I forgot to take some pictures. From an electrical point of view the installation was straight forward, but I had to make some changes to the battery holder, as the Super B has a different size than the Yuasa.
Of course I also had to test it, so I went on a on hour test flight. I already noticed the difference between the batteries when starting the engine, as the Super B delivers significantly more current to the starter, resulting in a much quicker and “cleaner” engine start. Throughout the flight all was as it should be, so no issues to report. Below some pictures taken during the flight, which show the spectacular views created by the layer of high clouds.
28.05.2021: My revalidation flight was due, and I tried to find a slot for weeks, but the weather was always pretty poor, and also unpredictable. Today however the forecast looked good, and our chief flight instructor had a training session scheduled with a flight student for the entire afternoon, so we agreed to do my checkflight right after that. I decided to rive to the airfield early and to do a bit of training before the checkflight. The weather was indeed very nice, again with a high layer of clouds as during my last flight, but only over the moutains.
The nearest skiing area is closed by now, but I noticed some Ratrac vehicles pusing around snow, as if they were preparing the slopes. But maybe they just spread out snow they had used to create a half pipe for snowboarders, so that i melts quicker, as such “structures” could take many weeks longer to melt than the normal layer of snow.
The revalidation flight went smoothly, we went throgh the various emergency procedures and made several off-airfield power-off emergency landing exercises with low go-arounds, followed by two “down to the ground” in Lommis.