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nitepilot79
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Posts: 1075
Joined: Tue May 20, 2008 9:10 pm

Flight Idle?

Sun Feb 21, 2010 11:37 pm

Just wondering what the definition of the "flight idle" power setting is. Thanks
 
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Jetlagged
Posts: 2564
Joined: Sun Jan 23, 2005 3:00 pm

RE: Flight Idle?

Sun Feb 21, 2010 11:54 pm

Flight idle is a higher idle setting used in flight. On approach, engine acceleration from ground idle rpm may take too longer for adequate safety during a go around. In such aircraft a higher idle rpm is used in flight which reduces the acceleration time. It's usually automatically selected, based on ground/air sensing logic and sometimes aircraft configuration as well (landing flaps selected or gear down for example).
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
Tristarsteve
Posts: 3692
Joined: Tue Nov 22, 2005 11:04 pm

RE: Flight Idle?

Mon Feb 22, 2010 4:36 am

Just to add a little.
There is a legal requirement that from idle to take off power must be acheived in 6 seconds.
This is set from flight idle.
On the ground, where this accel is not required the idle is reduced to ground idle.
On older engines this was a ground/flight sensing switch, but nowadays it usually comes from setting the flaps away from UP. On an A320 it is noticeable on the ground. After engine start to idle, you can hear the engines accelerate when the flaps are set to take off before taxy.
 
411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: Flight Idle?

Mon Feb 22, 2010 5:29 am

Quoting Tristarsteve (Reply 2):
There is a legal requirement that from idle to take off power must be acheived in 6 seconds

Must be for new(er) engines.
The JT4A, on the 'ole B707, was about twice that long.
IE: you could nearly go out to lunch waiting for that engine to spool-up....on the ground or in the air.
 
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IFixPlanes
Posts: 266
Joined: Sun Feb 20, 2005 11:34 pm

RE: Flight Idle?

Wed Feb 24, 2010 11:19 am

Quoting Tristarsteve (Reply 2):
... On the ground, where this accel is not required the idle is reduced to ground idle. ...

Correct.

Quoting Tristarsteve (Reply 2):
... On older engines this was a ground/flight sensing switch, but nowadays it usually comes from setting the flaps away from UP. On an A320 it is noticeable on the ground. After engine start to idle, you can hear the engines accelerate when the flaps are set to take off before taxy. ...

Sorry Steve, but that´s not true.
With flap lever position "not up" the engine goes up to approach idle only in air
never tell an engineer he is wrong ;-)

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