Wikiposts
Search
Tech Log The very best in practical technical discussion on the web

minimum OAT

Thread Tools
 
Search this Thread
 
Old 1st Jan 2014, 18:48
  #1 (permalink)  
Thread Starter
 
Join Date: Oct 2012
Location: Gagarin
Age: 44
Posts: 35
Likes: 0
Received 0 Likes on 0 Posts
minimum OAT

Is there any reason to set minimum operating ground temperature?
A320 FCOM limitations say min temp is-40 at 0 pressure altitude,but some planes have -46 temperature limit.What's wrong with the first planes???Why have they got -40 and other -46????
Thanks.
qwsa is offline  
Old 1st Jan 2014, 18:57
  #2 (permalink)  
 
Join Date: May 2011
Location: Home Counties
Age: 46
Posts: 596
Likes: 0
Received 9 Likes on 1 Post
Different fluid limitations (perhaps brakes?) ?
Globally Challenged is offline  
Old 1st Jan 2014, 19:35
  #3 (permalink)  
 
Join Date: Jan 2011
Location: Seattle
Posts: 717
Likes: 0
Received 3 Likes on 2 Posts
Globally Challenged

Different fluid limitations?
This is probably it. And not different fluids necessarily. System design and maintenance procedures have to start with some number. And then certify the design/procedures. So it could be as simple as the same fluid with different limits set for moisture absorption.

You could go to the manufacturer and request recertification to new limits. But every system will have to be investigated (fuel, lubrication, etc.) at the new numbers. That won't be cheap.
EEngr is offline  
Old 1st Jan 2014, 20:18
  #4 (permalink)  
 
Join Date: Mar 2006
Location: England
Posts: 997
Likes: 0
Received 6 Likes on 3 Posts
Ground tests during certification to demonstrate that doors, escape windows and slides all operate correctly.
PEI_3721 is offline  
Old 1st Jan 2014, 22:42
  #5 (permalink)  
 
Join Date: Jul 2013
Location: Everett, WA
Age: 68
Posts: 4,425
Received 180 Likes on 88 Posts
Could be fuel control components. Some seals and o-rings materials used in the fuel system don't work well below -40 and can result in excessive fuel leakage.
There are different seal/o-ring materials that work fine at -40, but wear out much quicker. So the engine companies sometimes give an operator option of the seal/o-ring materials in the fuel control - with different temperature limitations.
tdracer is online now  
Old 1st Jan 2014, 23:28
  #6 (permalink)  
 
Join Date: Aug 2013
Location: PA
Age: 59
Posts: 30
Likes: 0
Received 0 Likes on 0 Posts
737-8 that Conoco flies is good to -50.
underfire is offline  
Old 2nd Jan 2014, 02:24
  #7 (permalink)  
 
Join Date: Apr 2008
Location: nowhere
Posts: 1
Likes: 0
Received 0 Likes on 0 Posts
Probably the manufacturer only certifies down to a temperature that is required for what they expect sales for.

The ATR-42 had -40°C as its lowest OAT for takeoff(this is what I found on an internet search anyways) but I flew ones that had a lower temperature certified down to -54°C as it was operated in colder conditions. What exactly had to be done to achieve this? I'm not sure but I think our company paid the expenses to certify the lower OAT as they were purchased used.
JammedStab is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.