Originally Posted by Lemurian
1. You have ATHR on and SPEED managed mode---> Thrust target to maintain the chosen speed
2. you take the thrust lever out of the CLB detent --->TLA reduces the maximum EPR possible between max CLB EPR and Idle EPR = A/THR EPR target.
3. You have an A/THR disconnect after 1.8 seconds if 2 becomes too inferior to 1, meaning that A/THR can no longer maintain the managed speed.
You also get the A/THR Disconnect warning.
Yes, I figured it was an "involuntary disconnect", as FCOM calls it, with following thrust lock.
Thanks a lot for explaining. I'm trying to write up a short summary about that, but still can't quite figure it out exactly, and I don't like to make ill-informed posts
I understand that at diminishing airspeed there is an increasing EPR target that A/THR tries to set to set on the engine(s), but #2 was in CL detent, and surely one engine at CLIMB power would be enough to maintain 140kts even in CONF FULL.
[Edit: Nonsense about interaction between two FADECs deleted]
Oops, I got it completely wrong.
Thanks Lemurian for catching me! But see my other post, maybe I got it right now.
A/THR is a lot more complex than I imagined.
Bernd