B738, EEC altn./assumed temp
Thread Starter
Join Date: Jul 2006
Location: Norway
Age: 41
Posts: 122
Likes: 0
Received 0 Likes
on
0 Posts
B738, EEC altn./assumed temp
Hello gents
Can you guys tell me why it's not possible to use the assumed temperature reduced thrust method with EEC's in alternate mode?
Also, I read that during a takeoff in soft alternate mode the engine may windmill during takeoff, increasing N1 by as much as 7 %. What does the EEC do during normal conditions to stop this from happening?
Can you guys tell me why it's not possible to use the assumed temperature reduced thrust method with EEC's in alternate mode?
Also, I read that during a takeoff in soft alternate mode the engine may windmill during takeoff, increasing N1 by as much as 7 %. What does the EEC do during normal conditions to stop this from happening?
Join Date: Apr 2010
Location: Home soon
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
Can you guys tell me why it's not possible to use the assumed temperature reduced thrust method with EEC's in alternate mode?
Also, I read that during a takeoff in soft alternate mode the engine may windmill during takeoff, increasing N1 by as much as 7 %.
N1 may increase during roll out but yet again if you follow your DDG, a weight penalty will occur,reducing your N1 for the weight,keeping it below your max thrust rating N1 limit,even with 7 perc roll increase.(26k for actual conditions)
What does the EEC do during normal conditions to stop this from happening?
Last edited by de facto; 17th Sep 2012 at 09:38.
Thread Starter
Join Date: Jul 2006
Location: Norway
Age: 41
Posts: 122
Likes: 0
Received 0 Likes
on
0 Posts
Simple, Boeing says NO,not allowed.I guess its because you will use performance restrictions to calculate your vspeeds and you dont have ass temp tables provided for that condition.
You dont take off using soft alternate mode,you will be using the Hard Alt mode following your DDG.
N1 may increase during roll out but yet again if you follow your DDG, a weight penalty will occur,reducing your N1 for the weight,keeping it below your max thrust rating N1 limit,even with 7 perc roll increase.(26k for actual conditions)
N1 may increase during roll out but yet again if you follow your DDG, a weight penalty will occur,reducing your N1 for the weight,keeping it below your max thrust rating N1 limit,even with 7 perc roll increase.(26k for actual conditions)
Can the reason for the restriction be because of the lower thrust setting in the DDG? If you factor in a roll increase to maintain N1 within engine limits you couldn't count on those extra N1 figures for performance reasons..
Join Date: Apr 2010
Location: Home soon
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
Can the reason for the restriction be because of the lower thrust setting in the DDG? If you factor in a roll increase to maintain N1 within engine limits you couldn't count on those extra N1 figures for performance reasons..
To reduce the take off N1 ,your take Off limit weight is restricted by a certain weight value in the AFM DPI section....
but I still don't get the EEC in alternate.
Sorry,i am not sure but it .could be as simple as boeing can not know the temp the EEC in its reversion mode(alt) and therefore cannot provide assum temp table as climb and runway limit need the info of actual OAT.
Just a guess and stand to be corrected
Last edited by de facto; 17th Sep 2012 at 10:59.