Flyingnewbie10:
what feeds the TLA to the A/THR ? The resolvers or the potentiometers ?
The resolvers are the sole sensor inputs to the EECs (FADEC) regarding TLA.
The pots send their data to the flight control computers.
All in my post earlier
here where I thought a more detailed explanation of the A320 thrust lever design might be helpful.
which system does the FDR read the TLA from when A/THR is on ?
The resolvers or the potentiometers ?
This is an interesting question and one I had wondered about - A/T on or off. One would assume that since thrust commands (TLA or A/T) and actual thrust levels (EPR/N1) are key data points that the resolvers should provide the data for the manual thrust command FDR traces.
In practice I would imagine that the FDR gets filtered ARINC data from the EECs and no direct data from the resolvers. In A/T mode, the FDR should also have an recorded ARINC data channel from the FMGS-EEC interface. Ideally the potentiometers or resolvers should also have a direct trace on the FDR to preclude computer errors from being incorrectly recorded as actual control movements.
All that said, the Airbus manual thrust control system is fairly robust and typically industry standard.