One more random question. On the ramp yesterday she seamed to run great, started right up and just sewing machine smooth, but at full throttle I was not getting to take off RPM. Now this is with the plane tied and not moving at all, I would get to around 2300 but not hit redline. Does that actual movement of the plane through space get me to redline or do I have another problem to chase down?

Yeah, static RPM is always going to be a little less than your achievable in-flight RPM, and is dependent on which pitch prop you're running.

Mags are a good diagnostic item, but they generally won't cause a huge sudden RPM drop. They'll manifest as a tick or roughness. I think you had a water or fuel starvation event to lose that much RPM, especially if it wasn't a rough, violent symptom.

I like those ideas simply because it means nothing is catastrophically wrong!

Also thanks again to everybody with an idea, I can't tell you how much it has helped me, I'd be pretty lost right about now if it wasn't for the help!

Well, if your airbox is that screwed up, I'd definitely get it repaired. IT may or may not have been the cause of your problem, but it's not airworthy in any case.

That's been there for a while also, I'd bet. Might look for someone else to do your annuals in future.

MTV

mtv wrote:Well, if your airbox is that screwed up, I'd definitely get it repaired. IT may or may not have been the cause of your problem, but it's not airworthy in any case.

That's been there for a while also, I'd bet. Might look for someone else to do your annuals in future.

MTV

Maybe his faith in his mechanic may have been shaken a little.

tim

Zzz wrote:Mags are a good diagnostic item, but they generally won't cause a huge sudden RPM drop. They'll manifest as a tick or roughness. I think you had a water or fuel starvation event to lose that much RPM, especially if it wasn't a rough, violent symptom.

I had a similar forced landing situation last year. The engine wouldn't produce enough power to maintain altitude and so down I went. Checked all the fuel items, pulled plugs & cleaned them, took carb off and made sure of all the calibrations. Back on the ground, the engine would run just fine, the mags checks didn't show any unusual drop in RPMs. We thought we had the problem licked so went flying. Happened again. I endured 3 forced landings in one season before finding that the mags (Slick) were the issue. It seems that they would run fine for about an hour until the engine got good and hot and then they would break down and fail (or at least one of them was). I replaced both mags and haven't had any issues since.

Not saying this is your issue, but stranger things have happened. And yes, it was a large RPM drop and significant loss of power.