CFM56 Cool down time
 

Does somebody know something about a possible min cool down time of the CFM56 engines. I.E.: I used during landing max reverse and the apron is right there and taxying to the spot and engine shut down take less than 3 minutes!

Thanks volks

HPF

BA SOPs for CFMs is three minutes after use of reverse and three minutes when max reverse used on IAE engined aircraft.

Three minutes after "normal" use of reverse. Only one minute required if reverse was no more than idle.

What is the technical reason for the minimum time before engines off?

To allow the hot section of the engine to thermo stabilise (i.e. avoid shock cooling I think). I have seen presentation from CFM and they say min 1 minute, ideally 3 minutes to give long term preservation to the engine. Its suprising how many regional airports have aprons close to the runway so the inbound taxi time is short enough to cause it to be a problem.

So you may need to take a longer route to the apron or ask for different parking spot in order to cool down the engine?

Rwy in Sight

Not just regional airports! Land on 27R and if you get braking right you can be on a domestic stand in a few seconds. Quite embarrassing sitting there with the engines running waiting for our SOP 3 minutes.

That's good reason to (traffic permitting) let the aeroplane roll down the runway to the next exit. The longer taxi back will give you the extra cooldown time.

Of course when ATC says "expedite"... :ugh:

Oh no CaptainSandL....you are quite incorrect on this one.

I'm here now looking at the current CFM International SOIs, and they tell me that the 3 minutes is to be the normal, following the use of reverse thrust!

No mention of 'normal' or 'max', just reverse.

Taxi time can be used as part/all of this time.

The one minute cooldown time is an unusual once-not-to-often thingy, and is not to be come the norm.
But the one minute is the absolute minimum!

Also, just as an aside, warmup times in excess of three minutes before setting takeoff power, will reduce the maximum peak EGT during the takeoff, which is something we all like!

Cheers...FD...:ooh:

From my copy of the Boeing Operational Manual, Normal Procedures-Amplified Procedures:-
"If possible, after high thrust operation, including reverse thrust, run the engines at or near idle for three minutes before shutdown to cool the engine hot sections. Time at or near idle, such as taxiing before shutdown, is applicable to this three minute period. If needed, the engines may be shut down with a one minute cooling period. Routine cool down times of less than three minutes before shutdown are not recommended."
CC

http://i205.photobucket.com/albums/b...ex/CFM56-3.jpg
Everything you wanted to know on the CFM56-3 (Classic)
PPS 3.5mb.......

Cheers
TOD

http://us.f13.yahoofs.com/bc/4417428...wJsUGBGxm17uPu

And/or taxi to the ramp at a nice sedate speed!

The OM for Mechanics is the AMM.
There are two shut down procedures:
Stop the Engine Procedure (Usual Engine Stop)
http://img521.imageshack.us/img521/1...dureut6.th.jpg
If you cut off the fuel before wating the 3 minutes cooldown periode you can compare it with a flameout not caused by an engine failure:
Stop the Engine Procedure (Emergency Engine Stop)
http://img106.imageshack.us/img106/7...procsk1.th.jpg
So in my (technican) point of view, 3 minutes are minimum.
Shutting down without waiting the whole 3 minutes normally not end in a extreme damage of the engine, but lifetime and performance are reduced.