a few questions about the bleed system

[Guest s_L_Y_F_a]

since the bleedsystem usage is not described well enough in the manual I though why not asking the 744 community so here are my questions: 1. Pack reset - what is that good for? and when to use it?2. same with Zone reset3. Recirculation fans - when to use?4. gasper /humidifier - when to use?5. x-bleed - I saw this message in magenta on the lower EICAS after an engine failure next to the respective N2 bar. I know if this message is displayed u need to pull the engine-start switch of the respective engine to execute an in-flight engine start but what does x-bleed exactly mean?I will be much appreciated for answering

[markadeane 272]

This area is a bit foreign I'll admit but I'll have a go. Corrections welcome.1. and 2. I'll leave to someone else as I'm too vague on what function these have on the PMDG aircraft.3. Recirc fans should be on as part of your cockpit preparation upon power up of the APU.4. Gasper/Humidifier should be on once you have passengers in the cabin I believe (gaspers being the controllable air vents over the pax seats).5. x-bleed means cross-bleed and represents a situation where bleed air from the remaining engine(s) is *required* to effect a restart of the dead engine.EDIT: To change 'available' to 'required' under point 5. Thanks for the correction Andy!

[Guest andyman]

X-bleed on eicas 2 is if you are out of the "evelope" for a windmill restart, forcing you to use a cross bleed start.That's how i understand it.

[Jet Tech 31]

Hi Paul,The Zone and Pack reset switches are only used to reset a fault in either the Auto pack temp control system or a Zone Temp Control problem. Examples of these would be a Zone overtemp caused by a defective zone trim air valve or a Pack overtemp due to a Frozen ACM or temp control valve failure. The reset allows you to reset the fault and see if the operation returns to normal. If the reset is unsuccessful you will have to make the appropriate adjustments to the temp control system to regulate temps.RegardsPaul Gollnick :-cool Technical Operations/Customer Operational SupportPrecision Manuals Development Groupwww.precisionmanuals.comhttp://www.precisionmanuals.com/images/forum/devteam.jpg

[Guest s_L_Y_F_a]

wow guys thx for the quick response BIG THX!

[jon b 2,047]

3) recirc fans are normally on and basicaly just do as thier name suggests and recirculate used air through the cabin to make up the required airflow,rather than using air from the packs which as you know use engine bleed air.Interestingly though if you lose one of theese fans it will cost you extra fuel burn! What happens is the packs have to go into high flow mode to compensate for the reduced airflow and so take more bleed air and therefore more fuel is used. 0.3% extra fuel burn I think the exact figure is from the top of my head.It doesn`t sound a lot but on a London to California flight for example that will mean an extra 3-400kg of fuel!4) gaspers just control the air from those little individual vents above the passenger seats.Some extreme hot or cold temp procedures may call them to be on or off to try and control the cabin temp.Also as fans can be a source of electrical smoke or fire they can be turned off as required.The humidifier takes water from the onboard water supply and mixes it with the airconditioned air to the flight deck only,not the cabin,as we pilots worry about getting wrinkles! These are an airline option and infact have been deactivated on some airlines,the reason given is that they cause a chalky deposit in the overhead panels from the calcium in the water,but the real reason is probably they cost money and airline bosses don`t care if we get wrinklesregardsJon

[lostmoon 0]

when i go home to manila from new york, i bring along an evian water fine mist sprayer (or similar) and during those long hauls of cold and dry air, a spritz in the face really helps! Just keep the bottle close to your body for body heat, or else it gets too cold. It's also nice to inhale some of the mist to replenish the lungs with moisture. Moisturizer for the lungs!! :)But, the wrinkles make pilots look so distinguished! :()Jim