Originally Posted by
JRBarrett
Not much at altitude. Even so, with a full ACM that can cool the air using a compressor driving an expansion turbine, there can be a significant amount of water that condenses at the outlet of the turbine, and which is removed by a centrifugal water separator. That is mostly an issue on the ground when the ambient air is very humid.
At altitude, the cabin air supply tends to be extremely dry. Many people tend to have sinus problems when flying for hours in a pressurized cabin. Some aircraft (primarily airliners) have systems to humidify the cabin air.
How much maintenance experience do you have on Citations? I ask because you are wrong on several points. Freon A/C is used to augment cabin cooling and is off at cruise. All Citations use an Air Cycle Machine during cruise for cabin pressurization and temperature control. I have 2,500 hours flying them.
See pages 2-51- 2-57 here
http://www.corporatejetsolutions.com...g%20Manual.pdf