I've been writing about how stressed out I've been over this intermittent engine "knocking" when I fly above 8000-8500', and how my mechanic, and a mechanic here in Bisbee have done some very careful troubleshooting and could find nothing wrong. At Michelle Singh's suggestion, I called Lockwood Aviation this morning. I talked with one of their lead mechanics, who immediately knew what the problem is: the 912uls engine's carbs have mixture problems at these kinds of altitudes.
The answer? Move the needle jet circlet or fly lower! He said that's why many pilots in the west have gone to the Rotax 914 engine, which doesn't have this issue. In my case, we'll soon be out of these mountains, and until then I can follow I-10 through the mountain passes at a lower altitude.
What a relief! I was ready to bag the flight and ship the engine to Lockwood and trailer my plane home - THAT'S how stressed I've been over this.
Great news
ReplyDeleteSo sorry for the stress. You didn’t show it in your blog, just your common sense “let’s figure this out and stay safe” approach came through. Sure glad that’s all lifted now.
ReplyDeleteGlad you found a solution and safe travels for you!
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