A320 Thrust Rating Limit
 

Hi there!

I wonder if one of the A320 (family) experts here can answer the following question(s) regarding the A320's thrust rating limits:

- Which thrust rating limit does the FADEC choose if its thrust lever is moved IN BETWEEN two detents (e.g. between CLB and FLX/MCT or between FLX/MCT and TOGA)?
- And which thrust rating limit will be displayed on E/WD if the two thrust levers are not in the same detent, e.g. one lever in MCT and the other in TOGA?

And this leads to another (related) question regarding A/THR:

- with the A/THR being active (A/THR blue on FMA) and both thrust levers in CLB, what happens to the A/THR status if ONE lever is moved BETWEEN the CLB and MCT detents? Or even further into MCT or between MCT and TOGA or into TOGA?

Would appreciate any clarifying answer/explanation for a dummy like me. :) Thanks!

Phil

with A/Thr active it is not blue on FMA, it is white, only blue when armed, as for the other question, don't know.

A-320 A/thr
 

HI there,

I feel this about your queries,

The THR LIMIT will depend on the position of the THR LVR which is advanced further ahead.

Along with this you will have a lever assy message.

Hope this helps. If you have a diff reasoning do share it.

:cool:

Happy Landings

Yes, sorry...of course A/THR is white on FMA when active.

Does that also mean that when I move the thrust lever forward just a little bit out of MCT (and NOT into TOGA) detent I will get TOGA power?

You wont get TOGA power until it is in theTOGA detent.

Remember read your FMA it will tell you if the loop has been completed

on the FMA you will see MAN TOGA and of course you will see what N1 the FADEC has calculated on the eng display

Many thanks for your reply, guys!
May I bring up one of my original questions once more, please?

- with the A/THR being active (A/THR white on FMA), 2 ENGs operative, and both thrust levers in CLB, what happens to the A/THR status if ONE lever (not both!) is moved BETWEEN the CLB and MCT detents? Or even further into MCT or between MCT and TOGA or into TOGA? Will A/THR stay ACTIVE or revert to ARMED?


If A/THR remains active:

- and what will the A/THR system command e.g. in OP CLB? Will it go up to CLB PWR only on both engines (A/THR operating range 2 ENGs) or go even above CLB PWR on the engine with the thrust lever set above the CLB detent?

I somehow don't quite get the logic of all that... :ugh:

Thanks for any comments!

Logic...
With both engines operative, if you move one T/L above CL detent it becomes a manual T/L, and that engine will supply the selected thrust - it is progressive all the way to TOGA.
FCOM 1.22.30 p70 (look at the MAN THR line) ... says A/THR is armed and MAN THR will be displayed in White, unless the most advanced T/L is in the MCT or TOGA detent (MAN MCT or MAN TOGA in white). Logically the other engine will supply CL thrust since A/THR is only armed not active.
Logically yours..
TP

Thanks TP :ok:,

I understand what you mean. But what confuses me is the very first paragraph FCOM 1.22.30 P62 which says: "When both thrust levers are set above CL detent...the A/THR reverts from active to armed". It clearly mentions BOTH thrust levers.

The line you stated on 1.22.30 P70 (MAN THR) refers to the A/THR already being in ARMED status (e.g. after takeoff), but in my example A/THR is actually in ACTIVE status.

According to P62 A/THR would remain ACTIVE even with one T/L above CLB, in MCT or even in TOGA (with the other T/L still in CLB). The (confusing) question is: will A/THR stay within the range between IDLE and CLB or will it use more than CLB if required (e.g. OP CLB)...? :confused:

I'm curious... :)
Phil

Yes it is confusing! From p62 you would expect one engine to remain in A/THR active...I will try it in the simulator this evening and see what happens.
I understand this to mean that if MAN THR is annunciated, then A/THR is armed - I don't think ARMED is a previous condition.
The T/L position always limits the thrust, except in Alpha Floor - and OP CLB is not an A/THR mode!

Will post later/tomorrow after sim.
TP

>> OP CLB is not an A/THR mode

Yes I know, but assuming that AP/FD is in OP CLB mode A/THR (when active) uses "max CLB" thrust, right?
And the question is: will it go up to MCT on the engine with the T/L set in the MCT detent (which would give assymetric thrust) or will it remain at maximum CLB?

I am dying to know how the sim reacts... :D

Have fun in the sim and thanks for your help, TP!

Hi P.R.:

I just tried it today in the SIM:

One TL in a middle position between idle and climb detent, the other in climb detent while open climb mode engaged:

- A/THR stays active
- Thrust on one engine equals the TLA set
- Thrust on the other engine is climb power
- LVR ASYM flashing on the FMA

Result:
The "Bus" is giving you perfectly asymmetric thrust! :E

Hope it helped!

W.

Thank you very much, Wireflyer! :ok: