Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Fokker 70/100 Aircondition  
User currently offlineXaraB From Norway, joined Aug 2007, 210 posts, RR: 0
Posted (3 years 1 week 4 days 11 hours ago) and read 2152 times:

Hello everyone!

I have gotten to fly quite a few flights on Fokker 70s and 100s the last few months, and I have picked up a consistent "quirk" with this aircraft (i.e. happens on every flight):

Is the aircondition fan speed somehow directly connected to the engine revolution speed? Especially during approach, when thrust levels vary gratly, aircondition fan speed seems to follow these variations closely rather than being at a constant level. What is the rationale for this system design anyway?

Any technical insight would be greatly appreciated!

XaraB


An open mind is not an empty one
1 replies: All unread, jump to last
 
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (3 years 1 week 4 days 3 hours ago) and read 2072 times:

Quoting XaraB (Thread starter):
Is the aircondition fan speed somehow directly connected to the engine revolution speed? Especially during approach, when thrust levels vary gratly, aircondition fan speed seems to follow these variations closely rather than being at a constant level. What is the rationale for this system design anyway?

Like most jets, the Fokker 70/100 uses bleed air from the engines to power the air cycle machine. As the engine changes speed, the pressure at the bleed air tap also changes. In most designs, a regulator prevents changes in pressure at the bleed tap from going into the ECS system. However, when you're close to idle as you are in descent, even the highest bleed pressure may not be at the regulator set point so the regulator is wide open. When that happens, changes in engine speed translate directly to changes in bleed pressure and air cycle machine speed.

What you're hearing probably isn't actually a fan, it's changes in the airflow and air cycle machine speed. It's also possible that the recirculation fans are tied into the pack flow to hold a constant re-circulation percentage, in which case the re-circulation fan speed would also modulate with engine bleed pressure when the bleed pressure is low.

Tom.


Top Of Page
Forum Index

Reply To This Topic Fokker 70/100 Aircondition
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
Fokker 70 & 100 Cabin Luggage Bin Extension Option posted Fri Feb 8 2002 12:16:35 by Keesje
Questions About Fokker F70/100 - For Mechanics posted Wed Nov 22 2006 13:27:06 by Airbus-Insider
Most Profitable 70-100 Seater posted Mon Aug 7 2006 03:29:00 by Acjflyer
Thrust Reversers On The Fokker 70? posted Thu Feb 19 2004 00:39:04 by Mr Spaceman
Trying To Find A Fokker 100 Cockpit Poster posted Sun Aug 27 2006 02:57:55 by ANCSO
Fokker 100 Query posted Tue Jan 11 2005 16:36:01 by KLbambie
Fokker 100 Wings posted Thu Sep 23 2004 05:09:19 by Yhmfan
Pilots And Mechanics View On The Fokker 100? posted Sun Mar 23 2003 02:07:11 by Patroni
Fokker F-28? Or Is It An F-100? posted Tue Jan 14 2003 07:21:56 by Redngold
Fokker 100 Jet And Aerobridge Compatability posted Wed Apr 24 2002 18:42:37 by SixStarAnsett

Sponsor Message:
Printer friendly format