Engine Warm-up Procedures

[ENG]

I would be interested on views cocerning engine warm-up procedures to enhance engine efficiency and increase EGT margins. Presently my company starts engines and within 10-15 minutes are setting either T/O rated thrust or Reduced thrust for departure. Engine monitoring is giving reduced EGT margins and the company is looking for ways to increase them by developing warm-up procedures. The engine manufacturer are not very helpful. Without giving to much away the engines are old PWs. Views most welcome.

[spannersatcx]

Our engine run guides say that once stabilised at idle allow 5 mins for warm up, we can then go to max power if needed, so I guess 10-15 mins is good.

When we have problems with egt margins, normally a core wash gets a bit back.

[Techman]

The turbine section is thermally stabilized within 3-5 minutes of starting the engine. So any additional time will make no difference.

As spannersatcx says, a core wash will give you some 5-10 degrees C improvement on your EGT margin. All depending on the engine condition of course.

Another thing that can degrade the engine somewhat, is shutting it down before the turbine is stabilized thermally.

[PAXboy]

As the outsider ... may I ask what kind of scrubbing brush you use to wash the core? Seriously - please could some one give a shoret description of this procedure?

[spannersatcx]

Tie the fan down, motor the engine (minus fan) only the IP/HP sections rotate and squirt whatever detergent/agent recommended down the core.

[Techman]

Paxboy,

To put it simply, you point a hose at the engine inlet and while cranking the engine you open the tap. You can then add an abrasive material, like crushed nutshells, to remove any deposits in the engine.

[gas path]

We gave it up as it never seemed to make much difference, didn't seem worth the effort for just a couple of degrees. If that! The 211 doesn't suffer much of a margin problem anyway, over it's life, unlike some other powerplants, but they do make a damn fine bubble machine when that detergent gets blown out the back.;) ;)

[PAXboy]

Thanks gas path, I never realised that the true reason for Rolls-Royce going broke all those years ago, was that they were wasting their time making bubble machines for the discos, instead of donkeys. :=