DEECs and powerplant management

[LJ45]

I see and speak to many Learjet 45 drivers that are confusing the DEEC with FADEC. The FADEC is set it, forget it... The DEEC is not.

More info...Please!

 

[ultrarunner]

Set N1 according to the chart. That is limiting until ITT becomes the limit, and at somepoint on a 731 you will reach the ITT limit and subsequently will need to reduce N1.

I'm not aware that Garrett makes any of this a mystery in their AFM supplements. Do what the AFM tells you.

 

[svcta]

Well, they really don't give you anything other than basically "climb thrust setting as attained wihtthe thrust levers in the CLB position and by reference to N1" And it says that "max. climb thrust setting may be used throughout the climb segment...."In our a/c the thrust levers at that location gives us N1 that is below and ITTs way way below max climb thrust(recommended). Like around 100 degrees cooler. My question now becomes why are our settings so low at the CLB setting? Should that be altered at all? Any other G100 guys with similar experience?

 

[h25b]

More info...Please!

F ull A uthority D igital E ngine C ontrol

"Full Authority" being the operative words there...

 

[svcta]

That's great, everybody, but I'm not talking about FADEC. I wish I did but I don't fly an airplane that has it anymore.

 

[h25b]

That's great, everybody, but I'm not talking about FADEC. I wish I did but I don't fly an airplane that has it anymore.

With your specific aircraft I would say if it's operating that much below parameters it needs to go to the nearest Honeywell service center for some engine runs where they will most likely adjust the DEEC's. It would make me wonder whether you're actually attaining full T/O thrust in that detent. What does it do with the PL's in the T/O position? Are you getting book N1 within ITT limits ???

In the meantime I'd tell that guy to bring the power back to whatever the book numbers are, especially if the engines are on MSP and submitting the DEEC downloads to Jet-Care for trend monitoring. You'll have some explaining to do and will risk MSP not covering the next engine maintenance event.

 

[svcta]

We're going in for A/B check in a week so hopefully I can get those things looked at then. We are making good N1@ T/O setting(no detents on ours), and we're actually WAY below the max ITTs(in the climb & cruise) so I know we're not burning the things up. But the main question with me has turned to wondering why the ITTs are so low even near the proper N1 settings in climb. We're talking a hundred degrees. That just sounds like a lot of wasted headroom to me.

 

[Blackjet]

N1 is King. The DEECs have tattle-tales, so there's no covering up what Honeywell considers abuse. Have a look at the -40R climb and cruise instructions:
https://www.e-engines.honeywell.com...+Pilot+Tips+Booklet&commarea=Pilot+Tips+Books

 

[ultrarunner]

And it says that "max. climb thrust setting may be used throughout the climb segment...."In our a/c the thrust levers at that location gives us N1 that is below and ITTs way way below max climb thrust(recommended). Like around 100 degrees cooler.

When you're talking 'location', you're referencing the little pieces of tape that mx put next to the thurst levers when they set up the DEEC's? That was what i remembered when I flew a DEEC plane. Then at some point, mx removed those little pieces of tape.

I have not flow a -40 motor, so I can't speak for the N1/ITT relationship. Set N1 according to the chart. Don't sweat the pieces of tape. And have mx do the 12 point runs one night. It's no big deal so check to see if things are set correctly.

 

[HMR]

svtca- He must've discovered the mythical chart in the G100 or Astra AFM that relates to setting the temps to 900.

Are you familiar with the acronym, RTFM?