Losing power at relatively low altitude

[spotlope]

Here's something that's got me a little stumped: for the second time, I've been cruising in the Bo at around 5000-6000' when the power will begin to slowly fade. It feels like the mixture isn't leaned properly, except that it is, and changing the mixture in either direction has no effect. Left alone, the engine will continue losing power until the plane stalls (autopilot engaged in ALT mode). However, all I have to do to bring it back to full power is to descend by 1000' or so, and it comes back to life. The last time it happened, the OAT at altitude was below freezing, about 28 degrees (f) and there was visible moisture. It almost feels like carb icing, except that the Bo isn't carbureted, is it? My prop de-ice and pitot heat were on.So, you experts: what was I doing wrong?

[raymar]

The last time it happened, the OAT at altitude was below freezing, about 28 degrees (f) and there was visible moisture. It almost feels like carb icing, except that the Bo isn't carbureted, is it? My prop de-ice and pitot heat were on.So, you experts: what was I doing wrong?

What you were doing wrong was flying your Bo and enjoying yourself when you should have been working on one of those scenery packages. You were being punished. :( Actually, I have no idea, but, it sure sounds like carb ice.RayM

[spotlope]

LOL, I figured somebody would bust me for having ten minutes of fun. ;)If the problem is carb icing, should it happen at full throttle? I was always taught that it's only a problem at lower RPMs. And if that's what's happening, where the heck is the carb heat control?

[raymar]

If the problem is carb icing, should it happen at full throttle? I was always taught that it's only a problem at lower RPMs. And if that's what's happening, where the heck is the carb heat control?

The standard fsx key for Carb heat is . . . ready for this . . . HIt should toggle on/off with the press of the H key. I'm not exactly sure if you can see an immediate response to the key press but it that is the problem the engine should smooth out almost immediately.Ray

[Geofa]

The bonanza is fuel injected so it doesn't have a carburator but apparently there is a bug in fs that will still give you the symptoms and expect carb heat with the h key.I haven't experienced what you have mentioned but I have had the engine suddenly lose all power-manifold drop to zero-and then come up to full power a second later. Kinda cool and gets your attention.

[raymar]

The bonanza is fuel injected so it doesn't have a carburator but apparently there is a bug in fs that will still give you the symptoms and expect carb heat with the h key.I haven't experienced what you have mentioned but I have had the engine suddenly lose all power-manifold drop to zero-and then come up to full power a second later. Kinda cool and gets your attention.

That is the undocumented HRM system. Heart Rate Monitor. :(

[Geofa]

That is the undocumented HRM system. Heart Rate Monitor. :(

Good one!Yeah-I wonder if it is a "feature" in this plane or the carb heat bug also manifesting differently-I've had it happen several times.

[spotlope]

I had another flight this afternoon, and this time when the engine started losing steam I just leveled off and waited it out. After five minutes or so of sweating and watching the MP drop through the floor, it jumped back to live in a matter of seconds. There is definitely something squirrelly going on. Has anyone else seen this?

[Bob Scott]

I had another flight this afternoon, and this time when the engine started losing steam I just leveled off and waited it out. After five minutes or so of sweating and watching the MP drop through the floor, it jumped back to live in a matter of seconds. There is definitely something squirrelly going on. Has anyone else seen this?

Are you running a weather add-on? Take a look at the OAT when this happens...could be you're getting a big shift in ambient temp, which could cause this. ActiveSky has had some serious problems with this kind of thing (as well as some ambient pressure anomalies) for a while.RegardsBob ScottColonel, USAF (ret)ATP IMEL Gulfstream II-III-IV-VColorado Springs, CO

[spotlope]

Are you running a weather add-on? Take a look at the OAT when this happens...could be you're getting a big shift in ambient temp, which could cause this. ActiveSky has had some serious problems with this kind of thing (as well as some ambient pressure anomalies) for a while.RegardsBob ScottColonel, USAF (ret)ATP IMEL Gulfstream II-III-IV-VColorado Springs, CO

Thanks Bob, but in this case I wasn't running an external weather program. I checked the OAT when the power began falling off, and it was steady at around -4C. When the engine picked up again, the temp was the same. Good thought, though.

[Guest sg38]

Thanks Bob, but in this case I wasn't running an external weather program. I checked the OAT when the power began falling off, and it was steady at around -4C. When the engine picked up again, the temp was the same. Good thought, though.

Try the same flight at e.g. +20C and see what happens. Carb heat is a bit strange in FSX and maybe the conditions for that occurance or too widespread. Does the cfg file say 'fuel injected' ? Nevertheless I'd give the 'high temp' cruise a try, IF it doesn't occur than it's definitely carb ice...snd a programming error...

[spotlope]

Good idea, I'll do that when I get a chance.

[Butchm]

I posted about this as well previously... the problem I 'think' I am experiencing is at about 6-7000ft there does not seem to be not enough power. What MP pressure should you be able to hold at say 6000ft @ ISA? Butch

[Geofa]

I posted about this as well previously... the problem I 'think' I am experiencing is at about 6-7000ft there does not seem to be not enough power. What MP pressure should you be able to hold at say 6000ft @ ISA? Butch

Subtract 1" for every 1000 ft...approx 27" at sea level minus--- every thousand ft.

[GPHowell]

Good idea, I'll do that when I get a chance.

Hey,I've had the exact same problem, and with the Carenado Seneca too.In the F33A, I did a steady climb to 9000 with 2500 rpm and full throttle (MP goes from 27" down to about 18" during climb), leaning the mixture as I went to keep it smooth and MP just plummeted when I levelled out. I dropped 1000 feet or so then regained power. I was running ASE Weather at the time so maybe that is related? Haven't tried the carb-ice yet... I'll let you know...G