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nandrews

Default Mooney loses power at altitude

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I am flying the default Mooney Bravo on my 'round the world' flight.But I am frequently troubled by the engine losing power at altitude after variable periods and then recovering.The manifold pressure drops to around 4in! and the plane descends and then after some time the engine power returns and climbs.This last flight the power dropped and did not return all the way to the ground!!!I believe I have the mixture, anti ice, cowl flap all set OK.Can anyone clue me into what is going on here?ThanksNigel

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Hi Nigel,You're getting inducting icing, you can switch to alternate air and should see your power come back up. You can assign a keystroke for this function if you don't find a clickspot for it in the panel.

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Hi Nigel,You're getting inducting icing, you can switch to alternate air and should see your power come back up. You can assign a keystroke for this function if you don't find a clickspot for it in the panel.
It's the H key, IIRC.

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Thats probably not the answer,Unless you have it set for auto mixture, the higher you go the more you have to pull back the mixture. When you lean it out the RPM will go back up. You start this at around 3000 feet.Have fun,Randy

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zfehr,Thank-you for that.In my defence I did think of that, then that the Mooney powerplant has fuel injection so no carburetor to ice up!I also looked in the list of controls and the check list, but no mention there of alternate air.ThanksNigelP.S. I am surprised tho' in the final bit of my flight the engine never picked up right down to 2000ft, where previously it had recovered after a minute and around 9000ft.

Hi Nigel,You're getting inducting icing, you can switch to alternate air and should see your power come back up. You can assign a keystroke for this function if you don't find a clickspot for it in the panel.

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zfehr,Thank-you for that.In my defence I did think of that, then that the Mooney powerplant has fuel injection so no carburetor to ice up!I also looked in the list of controls and the check list, but no mention there of alternate air.ThanksNigelP.S. I am surprised tho' in the final bit of my flight the engine never picked up right down to 2000ft, where previously it had recovered after a minute and around 9000ft.
Induction icing is not the same as carburetor icing. The Baron's/Bonanza's have an automatic door that swings open for alternate air when induction icing occurs but as far as I know the Mooney's do not.

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zfehr,Thank-you for that.In my defence I did think of that, then that the Mooney powerplant has fuel injection so no carburetor to ice up!I also looked in the list of controls and the check list, but no mention there of alternate air.ThanksNigelP.S. I am surprised tho' in the final bit of my flight the engine never picked up right down to 2000ft, where previously it had recovered after a minute and around 9000ft.
This seems to be an FSX 'glitch'. Whenever I experiance this (typically when the weather gets colder/winter), I operate the 'carb heat' function whether the aircrfat has it or not, or injected or not.It almost always works.It some/most aircrfat, in cold weather, I simply try to remember to 'hit' carb heat before my flight.

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Induction icing is not the same as carburetor icing. The Baron's/Bonanza's have an automatic door that swings open for alternate air when induction icing occurs but as far as I know the Mooney's do not.
Geofa,Your vast real world aviation knowledge and your willingness to share it have been a great help to me over the years...thanks. (and thanks for the Lassen Mission, I'm from Redding) Just to pass this bit on...and return the favor...here is an excerpt from the M20M POH;"...ice particles may collect and freeze on the air filter causing partial or total blockage of the primary induction system. ...in extreme conditions...a loss of 10 inches Hg manifold pressure within one minute can be experienced...the alternate induction air system will automatically open...or manually opened by pulling the ALTERNATE AIR control..."Of course the automatic function in FS doesn't work for the default Money but the carb heat key code does operate the ALTENATE AIR control. Ron

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Hi and thanks to all for your contributions.I will use H on my next attempt at this flight.But I have already been leaning the mixture, so I believe if H will do for 'alternate air' then I should be OKThanks againNigel

Geofa,Your vast real world aviation knowledge and your willingness to share it have been a great help to me over the years...thanks. (and thanks for the Lassen Mission, I'm from Redding) Just to pass this bit on...and return the favor...here is an excerpt from the M20M POH;"...ice particles may collect and freeze on the air filter causing partial or total blockage of the primary induction system. ...in extreme conditions...a loss of 10 inches Hg manifold pressure within one minute can be experienced...the alternate induction air system will automatically open...or manually opened by pulling the ALTERNATE AIR control..."Of course the automatic function in FS doesn't work for the default Money but the carb heat key code does operate the ALTENATE AIR control. Ron

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It's been a problem in both FSX and FS9 (I don't go back further than that!) that fuel injected engines suffer from carb ice despite not having carburettors. I had several crashes and narrow escapes before I learned about the H key shortcut. On these trips, the alternate air control on the panel, which should have done for any induction ice, did absolutely squat.I'd say the problem is PROB90 carb ice, and if you were in any sort of cloud, PROB100.

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Thanks for all your help, but it didn't make any difference!I flew it again today and got to 16,000 with -14 outside. This time after about an hour the engine slowly started to lose power again. I had hit 'H' during the climb out (tho' no indications changed on the panel). After the engine began to slow down I hit 'H' again just in case but, no change.I declared an emergency and diverted, then at around 4000 the engine picked up again, but I was commited to the diversion.It's a real nuisance.Nigel

It's been a problem in both FSX and FS9 (I don't go back further than that!) that fuel injected engines suffer from carb ice despite not having carburettors. I had several crashes and narrow escapes before I learned about the H key shortcut. On these trips, the alternate air control on the panel, which should have done for any induction ice, did absolutely squat.I'd say the problem is PROB90 carb ice, and if you were in any sort of cloud, PROB100.

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Thanks for all your help, but it didn't make any difference!I flew it again today and got to 16,000 with -14 outside. This time after about an hour the engine slowly started to lose power again. I had hit 'H' during the climb out (tho' no indications changed on the panel). After the engine began to slow down I hit 'H' again just in case but, no change.I declared an emergency and diverted, then at around 4000 the engine picked up again, but I was commited to the diversion.It's a real nuisance.Nigel
Sounds rather bizarre. Just some obvious things to try-though you probably already checked them. Are you flying with full fuel?When you lean are you bringing the mixture back to where it runs rough-then enriching it slightly?Are you running at appropriate power settings?If you go at a lower altitude-say 6000-8000 -does the same happen?

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... I had hit 'H' during the climb out (tho' no indications changed on the panel). After the engine began to slow down I hit 'H' again just in case but, no change.
Are you referring to the pop-up panel, the "Annunciator Panel"? I tried it out in sever icing conditions. When the engine started losing power I hit the "H" key and the Master Caution light, Alt Air light and Prop Deice light came on. The alt air control handle has no effect. The engine came right back to life. I hit the "H" key and the previous mentioned lights went out. Shortly thereafter the engine started losing power again. This time I waited quite a while before hitting "H" again, at which time the engine took a little longer to come back to life again.If when you hit the "H" key the Master Caution light, Alt Air light and Prop Deice lights do not come on, could it be that you may have inadvertently re-assigned the "H" key to something else?

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A couple of other questions:Were you climbing at the time, or straight & level? If straight & level, how long had you been in the cruise (and what engine settings? MP, RPM, mixture)Were you in/near clouds, or in clear air?The fact that the engine didn't come back until 4000ft, ie losing 12000ft, still suggests it's an icing issue.(you could always try repeating the flight with the season set to Summer, and see if the problem goes away)

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Thanks to all for your continuing help in this matter.Just to summarize.The problem happens in the cruise (at around 16000 and often around -14 OAT). But upto an hour or more after entering the cruise.The engine is set at 34 on the manifold and 2400 RPMBoth anti-ice switches are set on before T/OThe cowl flap is often set the around 50%As my last RTW leg took me from Spain to Portugal the air has been a bit warmer (-11), though I still got about a minute of the engine slowly fading. Then it picked up again and continued to run OK for the rest of that flight.I did wonder if entering cloud might be a cause, but then didn't think FSX was that aware of what the cloud picture is. Tho' great if it is.I will see how the subsequent legs go as each will likely be getting warmer.Thanks againNigelP.S. I am flying the 1st Class Simulations 'RTW in 80 airports'. So far have done Farnborough (UK), Orly (France), Marseilles (France), Sion (Switzerland), Bilbao (Spain), Lisbon (Portugal)

A couple of other questions:Were you climbing at the time, or straight & level? If straight & level, how long had you been in the cruise (and what engine settings? MP, RPM, mixture)Were you in/near clouds, or in clear air?The fact that the engine didn't come back until 4000ft, ie losing 12000ft, still suggests it's an icing issue.(you could always try repeating the flight with the season set to Summer, and see if the problem goes away)

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