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SNS3Guppy..... Can i suggest that you read TopBunks original message again. I believe that you might have taken him up incorrectly. :ok:
Mutt |
General systems information is great for the tech log
As a note, we don't control the nature of tech discussion in Tech Log. So long as the thread is vaguely Tech in nature, at least, it is fine. The filtering system relies on those who aren't interested not reading the thread ... Some questions may get a "better" technical answer in the Engineers' Forum but that is not the point. As I see it, the main and underlying aim of Tech Log is the educational value for those coming up behind us old pharts ... Those who seek the black and white of the maintainers' point of view are always free to frequent and/or post in the Engineers' Forum. |
Can i suggest that you read TopBunks original message again. I believe that you might have taken him up incorrectly. |
Just to add my 'two-penneth'... the CSD oil cooler is actually an air exchange cooler and not a fuel/oil exchange cooler. You're confusing the engine oil system with that of the CSD Oil Cooling System. The engine oil is cooled by fuel; or conversely, the fuel is heated by the engine oil system. Which makes more sense don't you think? If the CSD was disconnected it wouldn't then provide any heating to the fuel system!
Just a retired Flight Engineer's perspective... it would appear that you flying chaps could do with a little technical expertise up there. You see what happens when we let you loose on your own! Happy days... now, where's my Gin & Tonic? TCF |
IDGs must be treated with respect.
A few years ago we had IDG temp advisories in the ECAM, or where they apparently spurious intermittent cautions? Anyway, after those everything was normal. We wrote it in the Tech Log. It occurred again in the flight next day and I asked the engineers. They said the IDG was OK and that they had refilled with oil. They checked again and everything was OK. Again they refilled. In the first occurrence I asked the captain if we should disconnet the IDG. In the second occurrence I strongly suggested the captain to do it. He decided not to. He did not want to lose a GEN. Later on I asked the engineers if oil consumption was normal and they said it wasn't. "So IDG is not OK" I replied. But they did all checks and it was OK. A few days later the whole engine was lost during cruise because of the IDG. The crew was unable to disconnect it with the pushbutton and it did a mess in the gear box. So if your IDGs are drinking oil like kosacks drink vodka... beware! |
A320 family CFM engines IDG oil...
CFMs for the oil cooling by the fuel...
The fuel recirculation system returns the warm fuel from the fuel cooled IDG oil cooler to the wing tank. The FADEC stops the recirculation system if: - the fuel temperature increases to a high level - the fuel flow rate to the engine is at a high level - the engines have a gravity fuel feed only - the fuel level in the wing tanks is low - the fuel goes into a vent surge tank. There is also a thermocouple in the IDG limiting the oil coming in thought the cooler that's temperature dependant. I seem to recall between 70-85°C it's open, but can't find the reference at the moment though |
IDGs must be treated with respect. A few years ago we had IDG temp advisories in the ECAM, or where they apparently spurious intermittent cautions? Anyway, after those everything was normal. We wrote it in the Tech Log. It occurred again in the flight next day and I asked the engineers. They said the IDG was OK and that they had refilled with oil. They checked again and everything was OK. Again they refilled. In the first occurrence I asked the captain if we should disconnet the IDG. In the second occurrence I strongly suggested the captain to do it. He decided not to. He did not want to lose a GEN. Later on I asked the engineers if oil consumption was normal and they said it wasn't. "So IDG is not OK" I replied. But they did all checks and it was OK. A few days later the whole engine was lost during cruise because of the IDG. The crew was unable to disconnect it with the pushbutton and it did a mess in the gear box. So if your IDGs are drinking oil like kosacks drink vodka... beware! |
On a related topic: on the A320 (CFM engines) the IDG oil is cooled by fuel under certain conditions (e.g. low thrust). Is any cooling provided at other times? I had an idea there was also a fan air heat exchanger, but can't find any mention of it in the current manuals.
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That's not the single most ignorant comment I've ever read here, but it's very close. You think systems knowledge and understanding is ridiculous, then? I'm alive thanks to systems knowledge and understanding, several times over. I'm very familiar with the school of thought that suggests one need no nothing beyond annunciators and ECAM messages...but I also strongly disagree. I don't think you can ever know enough about your airplane. I also strongly believe that one who enters the forum asking an honest question deserves to get an honest answer, and not ridicule for asking. |
IDG cooling is more usually Air/oil - the increase in temperature on a disconnected IDG or CSD is caused by heat soak from the still running engine,there being no oil circulation on the dead IDG.
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Cooling.Lubrication.Heat transfer.
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THE CSD part of an IDG uses the oil as a hydraulic fluid to drive a hydraulic motor the output of which is summed with the geared rotation to maintain a constant output speed to the generator.
Can you obtain an ATP these days with no knowledge of CSDs? The oil is also used for the cooling and lubrication of the entire device. |
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