Hey folks, I haven’t posted here in a while (nothing personal...striving to spend more time off line than on...) but I had a carb ice experience yesterday I thought I’d share. I did a search for carb ice here and found lots of threads so this isn’t a unique situation, but it was a first for me in 40+ years of Cubbing. I’ve had carb ice a few times before but never with this intensity at cruise. The engine is a freshly overhauled (less than 20 hours) C85 stoker with a freshly overhauled MS MA-3SPA carb.
I took my brother in law for a ride yesterday afternoon, about a half hour before sunset. Northern IL, high 30s, calm and a beautiful evening. About 20 minutes into cruise at 2000’ and around 2300 rpm she quit, at least the rpm rolled back like I had pulled it to idle. No roughness, no coughing, just wound down. Immediate carb heat brought her right back again with no roughness from melted ice passing through the carb.
After about 30-40 seconds I pushed he carb heat back in, there was a slight increase in rpm and we motored on, but at a slightly higher 2400 rpm. A few minutes later it happened again, same correction and same results. I did leave the carb heat in a bit longer and then bumped it to 2500. We were headed back to the pattern anyway since it was almost sunset when it happened a third time. OK, this time the ice wins. We are three miles from the airport and the carb heat stays on for the rest of the flight. I had assumed the first occurrences were due to slightly reduce power settings. I was wrong.
I checked the temp and dew point when we got out. Temp was 4C and dew point was -2C. This was 15 minutes after the first occurrence but since it was a high overcast day and temps cooled off fairly quickly as sunset approached, I’d expect the temp/dew point at 2000’ was about the same.
We’ve flown this airplane year round in Northern Illinois winters for the last six years and this was my first encounter with carb ice. There are a dozen Cubs on our field and I haven’t heard any of the other owners ever comment on this phenomenon. I just found it interesting that yesterday was the perfect combo of temp and humidity for my engine/card/cowl to imitate a snow making machine.
A side not: LOVE, LOVE, LOVE the Stroker. I did the overhaul with the Aircraft Specialties STC, new crank, 4 new cylinders and new exhaust. One day soon I’ll write up the circumstances leading to the overhaul and the process in the powerplant section. Not only is the increased power noticeable but the heater is much more effective as well. Now, I’m not saying it good-it’s still a Cub heater-but it is noticeably improved. That was comforting knowing the same system was pumping nice warm air into my carb.
Happy thanksgiving to everyone and enjoy your turkey day flying. I’m always amazed that after 43 years of Cubbing this old pilot can still learn things from this old airplane. Thanks for letting me share.
I took my brother in law for a ride yesterday afternoon, about a half hour before sunset. Northern IL, high 30s, calm and a beautiful evening. About 20 minutes into cruise at 2000’ and around 2300 rpm she quit, at least the rpm rolled back like I had pulled it to idle. No roughness, no coughing, just wound down. Immediate carb heat brought her right back again with no roughness from melted ice passing through the carb.
After about 30-40 seconds I pushed he carb heat back in, there was a slight increase in rpm and we motored on, but at a slightly higher 2400 rpm. A few minutes later it happened again, same correction and same results. I did leave the carb heat in a bit longer and then bumped it to 2500. We were headed back to the pattern anyway since it was almost sunset when it happened a third time. OK, this time the ice wins. We are three miles from the airport and the carb heat stays on for the rest of the flight. I had assumed the first occurrences were due to slightly reduce power settings. I was wrong.
I checked the temp and dew point when we got out. Temp was 4C and dew point was -2C. This was 15 minutes after the first occurrence but since it was a high overcast day and temps cooled off fairly quickly as sunset approached, I’d expect the temp/dew point at 2000’ was about the same.
We’ve flown this airplane year round in Northern Illinois winters for the last six years and this was my first encounter with carb ice. There are a dozen Cubs on our field and I haven’t heard any of the other owners ever comment on this phenomenon. I just found it interesting that yesterday was the perfect combo of temp and humidity for my engine/card/cowl to imitate a snow making machine.
A side not: LOVE, LOVE, LOVE the Stroker. I did the overhaul with the Aircraft Specialties STC, new crank, 4 new cylinders and new exhaust. One day soon I’ll write up the circumstances leading to the overhaul and the process in the powerplant section. Not only is the increased power noticeable but the heater is much more effective as well. Now, I’m not saying it good-it’s still a Cub heater-but it is noticeably improved. That was comforting knowing the same system was pumping nice warm air into my carb.
Happy thanksgiving to everyone and enjoy your turkey day flying. I’m always amazed that after 43 years of Cubbing this old pilot can still learn things from this old airplane. Thanks for letting me share.
