Archived

This topic is now archived and is closed to further replies.

regamuffin

Bleed Air Fault 123 Md11

Recommended Posts

Hey guys there might be a real simply answer to this but i aint figured it out yet lol, once iv been flying for prob just over half hour anti ice on i get a system amber fault message on the md11 saying bleedair fault 1 and same for engine 2 and 3 too stays on for a while this goes and comes back is this anything to do with the anti ice being on or what im not a hundread percent sure on this fault also i get a indication no ice deteced even though its like -50c up in the air lol but i would still have the anti ice on. if anyone can answers this be a great help cheers guys.Paul

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

You wouldn't have anti ice on while at Cruise with -50c you only use it in clouds or when there is visible moisture.Rob

Share this post


Link to post
Share on other sites

Engine and wing Anti ice use bleed air. It can't be good for the aircraft leaving it on in cruise for long periods. However I'm sure one of the MD11 experts on here could explain better.CheersRob

Share this post


Link to post
Share on other sites

I get this message when using AI in descent. You need more engine thrust to support wing AI. Just push the throttles until it dissapears.Alex

Share this post


Link to post
Share on other sites

'I get this message when using AI in descent. You need more engine thrust to support wing AI. Just push the throttles until it dissapears'That shouldn't be the case, Thrust should automaticly increase to compensate. Put the aircraft on the ground with idle thrust, monitor N1 or EPR and watch what happens when you engage nacelle anti ice. This is modelled in the 744 so must be on the MD11Rob

Share this post


Link to post
Share on other sites

The MD-11 does not compensate for low bleed air by increasing engine thrust in the air. On the ground, the engines are brought up to flight idle when A/I is used on the ground, however in the air you cannot go below flight idle. For that reason, in descents requring bleed air, shallow descents or those with spoilers/flaps are recommended to allow the engines to maintain a higher N2.

Share this post


Link to post
Share on other sites
Engine and wing Anti ice use bleed air. It can't be good for the aircraft leaving it on in cruise for long periods. However I'm sure one of the MD11 experts on here could explain better.
I get this message when using AI in descent. You need more engine thrust to support wing AI. Just push the throttles until it dissapears.
It's more of a common aircraft deal. Well, it's common to those that are pressurized and have engine-bleed AI. Remember that the bleed feeds the pressurization system, so there's bleed coming off of the engine thrust. When you try to add wing/engine AI, you're trying to pull off more bleed. If the engine thrust setting is too low, there isn't a lot of bleed to drag out of the engine for the packs, much less the AI. I don't have the MD-11, so I can't tell you exactly what's going on, but I know that on other add-ons, they show a ring or marker on the EICAS of the minimum thrust required for the AI to work.I'm not an AI expert, but I do know that the temperature has to be low enough for the water to freeze on contact with the aircraft, yet high enough that the water is not already frozen. If the water is already frozen, there's little chance of accumulation on the aircraft. At the FLs, that's generally the case, so AI is not needed. It's the getting up and getting back down that brings the danger of icing, generally.With engine AI, the general procedure is to turn it on when temps are below 10C with visible moisture (clouds/fog), but above -40C.Wing AI is used whenever you're in icing conditions. This is subject to more airline-to-airline policy changes. It is also more subject to manufacturer differences. Some will work on the ground and only shut off in a certain config (take-off thrust for some, etc), some don't work on the ground at all.This is from my old Independence Air A319 FSM:
The engine anti-ice system must be on during all ground and flight operationswhen icing conditions exist. This includes taxi-in to the gate.Regardless of SAT, engine anti-ice must be ON prior to and during descent invisible moisture when TAT is 10

Share this post


Link to post
Share on other sites

Kyle great post, Allan is this MD11 specific? on the 744 in the DES FORECAST I have to tell the aircraft when I am planning to use AI so it can re compute the VNAV path.Studying the MD11 and a lot to learn :)ThanksRob

Share this post


Link to post
Share on other sites
Kyle great post, Allan is this MD11 specific? on the 744 in the DES FORECAST I have to tell the aircraft when I am planning to use AI so it can re compute the VNAV path.Studying the MD11 and a lot to learn :)ThanksRob
Same for MD11 :)@6679In the air, you actually can go below flight idle. During normal idle descents the ECU provides minimum idle (ground idle) . Approach idle (flight idle) is automatically selected when slats/flaps are extended or anti-ice is on.Floris

Share this post


Link to post
Share on other sites

Just my two cents, the problem isn't so much pressure (there's lots of air available) as temperature. I've noticed a bleed air temp below 140 cause the bleed air advisory. A couple of line pilots in the beta team have mentioned they will use slats and spoilers as required to get the temp up for a working ice prevention.

Share this post


Link to post
Share on other sites

Hey Dan, can you explain more? The use of spoilers for AI seems extremely inefficient from a carriers perspective or are we seeing a sim world issue? We all know the MD11 was unfortunately not sucesfull except in the freighter config so is this a strange quirk on the aircraft?ThanksRob

Share this post


Link to post
Share on other sites

Spoilers only if needed, I assumed that the slats helped enough in most cases. My specific questions was what was their common practice.

Share this post


Link to post
Share on other sites
Spoilers only if needed, I assumed that the slats helped enough in most cases. My specific questions was what was their common practice.
Interesting, I don't see any relationship between spoilers and bleed air temperatures. Can you explain this please?Best regards,Floris

Share this post


Link to post
Share on other sites

Sure there is, the incease drag requires additional thrust and moving the throttles above idle will increase the temps. So far, I've only needed slats which allowed me to add thrust to maintain the PROF IAS setpoint. Again, all it takes it a little extra N1 to move the bleed temp above 140. Put the AIR screen on the SD and you'll see what I'm trying to explain.

Share this post


Link to post
Share on other sites
Sure there is, the incease drag requires additional thrust and moving the throttles above idle will increase the temps. So far, I've only needed slats which allowed me to add thrust to maintain the PROF IAS setpoint. Again, all it takes it a little extra N1 to move the bleed temp above 140. Put the AIR screen on the SD and you'll see what I'm trying to explain.
Ah, I get it. I would love to try it on the sim, but I am still waiting for the FS9 version, and I haven't seen this 'problem' in real life yet :)

Share this post


Link to post
Share on other sites

Just curious if any PMDG Aircraft are modeled for icing effects.John

Share this post


Link to post
Share on other sites
Interesting, I don't see any relationship between spoilers and bleed air temperatures. Can you explain this please?Best regards,Floris
Floris,Yes, you are correct. I will be careful to check what I write before submitting my posts in the future. :)

Share this post


Link to post
Share on other sites