Isham Posted December 18, 2020 Report Share Posted December 18, 2020 Today my check engine light came on several times. Cruise at 4900 RPM and the Left EGT signal was going above 1550 which seemed to be setting off the light. It would not stay there, but went back below 1500 each time. Tried some other power settings but problem persisted. Is there a common issue on the EGT? The right bank stayed around 1450 all of the time. Thanks. Quote Link to comment Share on other sites More sharing options...
Tip Posted December 18, 2020 Report Share Posted December 18, 2020 I once had both EGTs go above the alarm setting. I’m convinced that it was carb ice. I pulled on carb heat and they returned to the normal range. Quote Link to comment Share on other sites More sharing options...
Isham Posted December 19, 2020 Author Report Share Posted December 19, 2020 About 40 degrees. Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted December 19, 2020 Report Share Posted December 19, 2020 First off in my experience the Bing carbs run the leanest right around that 4900-5000 RPM mark, so you should expect higher EGT's in that RPM range. Also colder weather will make the EGT's go up too. EGT probes are relatively inexpensive as airplane parts go. $35 dollars at Aircraft spruce. They are also fairly easy to change out. If there is an issue with the engine changing out the probe will not fix the problem, but it is somewhat cheap troubleshooting. Replace the one with the higher indication first. Make sure the carb is fully seated in the socket. I saw an airplane the other day that was getting a SPN warning on the Dynon, and the carb was loose in the socket. Check the vent tube that goes through the airbox. Make sure none of the scallops are exposed, and that the connections are good all the way to the carb. It might be worth doing a pneumatic carb balance to make sure that they are the same. If all of this checks out it might be time to do a carb inspection, and pay close attention to the idle jet. Also make sure the circlip is in the correct groove on the needle. Quote Link to comment Share on other sites More sharing options...
Tip Posted December 19, 2020 Report Share Posted December 19, 2020 Hey Bill, My guess would be 40 degrees. I had a post about it years ago. I’ll see if I can find it. There’s no doubt in my mind that it was carb ice. The EGTs started to move above the 1500s and just after that, the engine change sounds. Ivan looked over at me and said “did you hear that”. I pulled the carb heat on for about 30 minutes and we continued on a 4 hour round trip. Quote Link to comment Share on other sites More sharing options...
Tip Posted December 19, 2020 Report Share Posted December 19, 2020 Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted December 19, 2020 Report Share Posted December 19, 2020 The most common range for carb ice in the Rotax 912 is OAT around 60°F and high humidity, from what I have read. It can of course occur in other conditions, but when the temps are 50°-65°F I pay closer attention to the humidity and have carb heat on my mind in case of engine roughness. Quote Link to comment Share on other sites More sharing options...
Isham Posted December 29, 2020 Author Report Share Posted December 29, 2020 Hi Bill and thanks for the carb ice input. You are exactly right. No issue on several flights since. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.