Manfred DC3, engine goes idle at 10,000 ft.

[guitar0633]

It has happened two times in a row. Followed check list. Map 1t 26, rpm 2150. NO red marks anywhere on the control panel besides OAT showing like -18. I had prop heat on, no deice on since nothing in the red. I was going from CFA4 to CAB% Bronson Creek in Alaska. Abouthalf way through the engines drop to idle. I did have cowl flaps open to number 6 but when I take them to like 2 the CHT goes up to the yellow. My fuel main r and L were at 81 percent full and the aux were at like 30 percent ( I don't know where the fuel tank selector is, hope someone can tell me). I can click and check the amounts in all tanks during the checklist. When it dropped to idle they were at 81 percent, plenty of fuel.
Carb heat was on and said Hot in red on the panel. I turned carb heat soon after takeoff.

I am in FSX Acceleration. She flies great and then all of the sudden the engines go to idle. I tried turning the backup suction pump on, no help.
No fire or anything, the engines just idle and moving the throttles won't change anything. Mixture was in AL, I had them manually set to about 50 percent r a little less.
I can't figure it out., hope someone can help me. Thanks

[guitar0633]

It has happened two times in a row. Followed check list. Map 1t 26, rpm 2150. NO red marks anywhere on the control panel besides OAT showing like -18. I had prop heat on, no deice on since nothing in the red. I was going from CFA4 to CAB% Bronson Creek in Alaska. Abouthalf way through the engines drop to idle. I did have cowl flaps open to number 6 but when I take them to like 2 the CHT goes up to the yellow. My fuel main r and L were at 81 percent full and the aux were at like 30 percent ( I don't know where the fuel tank selector is, hope someone can tell me). I can click and check the amounts in all tanks during the checklist. When it dropped to idle they were at 81 percent, plenty of fuel.
Carb heat was on and said Hot in red on the panel. I turned carb heat soon after takeoff.

I am in FSX Acceleration. She flies great and then all of the sudden the engines go to idle. I tried turning the backup suction pump on, no help.
No fire or anything, the engines just idle and moving the throttles won't change anything. Mixture was in AL, I had them manually set to about 50 percent r a little less.
I can't figure it out., hope someone can help me. Thanks

I also had time acceleration set to 4. Not sure why that would matter though unless something changed very quickly and I didn't see the failure, but I immediately went back to normal time and still saw nothing out of the ordinary as I went down. It took a while to float down so I had to to try everything I could think of.

Can someone also tell me the best way to handle cowl flaps with this baby? Should I keep them say, at half open during climb when the engine is running harder and then close them completely when I get to cruise?

[MrZippy]

I also had time acceleration set to 4. Not sure why that would matter though unless something changed very quickly and I didn't see the failure, but I immediately went back to normal time and still saw nothing out of the ordinary as I went down. It took a while to float down so I had to to try everything I could think of.

Can someone also tell me the best way to handle cowl flaps with this baby? Should I keep them say, at half open during climb when the engine is running harder and then close them completely when I get to cruise?

Keep cowl flaps open a bit while climbing and close them at cruise altitude. You never mentioned Prop RPM. Are you in the green zone somewhere between 22-28? OK, I see you mentioned 2150 for RPM. Pitot Heat on?

If engines are at idle, then moving the throttles would get a response from the engines. No response would mean engine shutdown.

[Roger]

guitar0633, Manfred Dc3 is a member here but not the maker of the C-47. Mjahn and his team made the model I think you're referring to.

[BendyFlyer]

guitar0633 - To me sounds like classic symptoms of carburettor icing. First with cowl flaps you need to be full open on the ground until before take-off and then set them to about 70% for take off, if the OAT is about 10C or less in which case you can bring the cowl flaps back to about 30%. Gradually bring them back to trail (about 10%) on the climb and then when established in the cruise set them to closed. The trick with these aeroplanes is to monitor the CYL HEAD temps and keep them in the green range all the time. You do this via mixture and cowl flaps. Generally it is mixture full rich or autorich below 5000 ft then you can lean them off as you climb as a rule of thumb you should be about 45%-35% at altitude. A good trick is to lean the mixtures to keep the cylinder head temps at the top of the green range and generally you will find that if you lean them right off until the engine starts to want to stop or chokes them richen them back up again smoothly until they are running smoothly. IN all piston engined aeroplanes mixture is managed by reference to the cyl head temps, so if they get hot you richen up the mixture if they are starting to run a little cool you lean them off a bit.

I am not sure how the FSX engine models carb icing but it appears to me to be quite realistic. You can expect carb icing in air temps of between plus 10 and minus 5 with visible moisture (clouds about). In the real world you can determine if it is carb icing by the loss of MP (as the inlet thickens with ice) putting carb heat is not instantaneous but may take several minutes to clear the throats of the carburettor and you will see a rise in MP as a result, if you experience carb ice keep them on till clear of cloud. The thing about carb heat is that you loose a little performance or engine power but not enough to matter really compared to iced up carburettors. If you are flying an aeroplane with fuel injection then you do not need carb heat but the C-47 had an interesting composite sort of carburettor that had some injection but basically still had a large throat. The venturi affect of accelerating flow of air in the carb throat and fuel is what does the damage in a carburettor, the temp drops inside the throat and it is this drop compared to outside that will cause ice to form if there is moisture in the atmosphere. With regards to cooling you may find in a hot environment that you need to reduce the climb angle and climb very slowly to keep the engines cool but and here is the catch even in the hottest world once your at altitude and have moisture about you can get carb icing because of that pressure change and air acceleration in the carburettor. Tricky buggers to manage well are piston engines but once you get the hang of it you will enjoy them.

Another rule of thumb with pistons was whenever you may be anticipating low rpm settings such as on descent etc you would put the carb heat on anyway just in case, better to have the enines a little warmer than have them choke with ice and then not respond when you want them too. What you have described is to me classic carb icing symptoms, the power just dwindles away bit by bit. Always something to do up front!

[lazarus]

I don't know if FSX models this or not. Real world, if you have an EGT, to set the mixture you'll lean out until you start to see an EGT rise, then nudge it up a hair. Cylinder head temp, as noted is past crucial. A ham-fisted driver banging the throttles about and not watching the CHT will frag an engine faster than you can say 'total internal failure'. I also note that FSX really doesn't do cowl flaps well. The DC-4/6, Cl-215, A-26 ect-aircraft with the big ring of cowl flaps- it's a juggling act between CHT and drag- too closed, the engines cook, or, in arctic conditions- over-cool and thermal shock (all of which lead to valve and cylinder failure- usually the cylinder 'ears' bust off, the valve goes down the jug, beats a hole in the piston, the rod lets go, and things get really ugly)
Too much cowl flap and you're running a real risk of no acceleration/ no lift and eating the trees out off the threshold. The right seat filler on the -4's,-6's and -215's main job is riding the cowl flaps, CHT and mixture.

[guitar0633]

Keep cowl flaps open a bit while climbing and close them at cruise altitude. You never mentioned Prop RPM. Are you in the green zone somewhere between 22-28? OK, I see you mentioned 2150 for RPM. Pitot Heat on?

If engines are at idle, then moving the throttles would get a response from the engines. No response would mean engine shutdown.

I mentioned the prop rpm in first sentence. On the idle, the throttle I moved forward and backwards, the engine never responded but just idked on it's own. BUT. I think I know the problem. I did the flight again and made i all the way. I happened to notice the note paper stuck on the panel and for some reason I thought it said Map should be at 26 inch for cruise, and it didn't, it said 30-34 or so. I et the prop t0o 2150 and and set the map to 32.4 and she cruised all the way there. Yeah. I finally noticed that on the cowls I could set them to trailing and they would be automatic. So I believe I was running with the map at only 26 inches for too long and it caught up to me.

I'll fly her a few more times and will update this thread if I have any problems. Thanks for the responses guys, this place is so helpful.

[stansdds]

I suspect the issue is carburetor icing.

[roger-wilco-66]

You also might check your mixture settings.
I go up to 18000 feet when I cross the hump regularly. There is some considerable leaning to do on the way up, otherwise one never would get that high.

Never had carb icing, but I watch the temps.

Cheers,
Mark