I am having trouble with engines on my Islander: Sometimes, after significantly reducing power on approach they are totally unreponsive to an increase in throttle with drastic consequences.
I am 90% certain that it is not carburettor icing - the problem seems to occur if the RPM drops out of the green for any length of time. Then pushing the throttle leavers forward has no effect and I end up in the sea off St Mary’s. It is strange that it does not seem to happen on every flight.
I’ve never experienced this in almost 2 years and i’m not seeing it reported. You say your 90% sure its not icing, but have you tried adjusting the carb heat?
It will be the carb ice. The carb ice model on this Islander is very aggressive. It’s also not a case of just increasing the carb temp until the needles are out of the danger zone. If you notice reduced performance give it full carb heat to clear the icing until the expected performance returns.
Keep a close eye on the carb temp gauges. You’ll be surprised to find that they often stay just inside the yellow arc with no heat applied, even on a warm day. I find that putting my mouse over each lever and rolling in just 2-3 notches of heat will take the needles above the yellow arcs without compromising performance.
In the real world, leaving the heat on full thins out the air going into the engine and degrades performance. I’m not sure how well this is modeled in the Islander, but I figure why take a chance on flight issues.
It’s caught me out a few times, usually on approach when it is the most untimely.