Engine start-idle thrust
 

HY. I wonder if you know anything about a minimum required time to keep the engine at idle trust before advancing the engines at takeoff thrust?
On our books for CFM on 737 says nothing on this subject.
What about the airbus engines?
I know it is not usual to start the engines and takeoff in 1-2 min,but just from a technical point of view?
Brgds Alex

Hi

On our V2500 equiped A320s, the rule is if the aircraft hasn't flown for two hours or more then they need 5 minutes at idle before applying takeoff power. And after landing they need two minutes at idle before shutdown.

Hope that helps



Santan

757 needs oil temp to be above 0 degrees Centigrade before ANY extra thrust is applied...
Only usually applicable when they get sent to Canada in winter and nightstop!!!

:ooh:

Our V2500's need 3 mins at idle thrust after landing and 3 mins before take-off if less than 2 hrs on ground. We are the same as Santan on the 5 mins if time on ground greater than 2 hrs.

Understand RR Trents for example are very different (3 spools = quicker heat equalisation?)

:ok:

as I see,untill now nothing regarding the CFM engines.
Why do they not specify nothing regarding limitations for this engines? Are these engines somehow different from the V2500?

Hi alexban,
my understanding with the B737NG CFM56-7 engine is that,
when the OAT is -35 to -40 degC, the engine is to be held at idle for two minutes.
Then an overall statement that says that anytime the engine oil pressure is outside the normal operatiung range, stay at idle.

Then, after landing, the normal cooldown time should be three minutes, but if its absolutely needed, one will suffice.

After 3 or more hours cold soak at -40 or less, do not start or motor until maintenance has done their procedure with the starter.

hope this helps,
FD

Never seen any hard and fast rule here on CFM56-3's but I've always given 5 mins at idle before ground running at T/O power, and same after high power runs.