Jump to content

a few questions about the bleed system


Guest s_L_Y_F_a

Recommended Posts

Guest s_L_Y_F_a
Posted

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

Posted

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!

Mark Adeane - NZWN
Boeing777_Banner_BetaTeam.jpg

Guest andyman
Posted

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.

  • Commercial Member
Posted

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

Paul Gollnick

Manager Customer/Technical Support

Precision Manuals Development Group

www.precisionmanuals.com

PMDG_NGX_Dev_Team.jpg

Guest s_L_Y_F_a
Posted

wow guys thx for the quick response BIG THX!

Posted

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

787 captain.  

Previously 24 years on 747-400.Technical advisor on PMDG 747 legacy versions QOTS 1 , FS9 and Aerowinx PS1. 

Posted

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

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
×
×
  • Create New...