takata
CG set at max envelope aft should not be an issue for handling in direct law if one is carefull about not over controlling (elevators are really powerfull at high altitude). In any circumstance, with full aft CG, (beside some related FCMC faults) Airbus state that no forward fuel transfer is needed (turbulences, whatever...). Nonetheless, direct pitch is loosing autotrim and, during normal operation at cruise, there is a constant displacement of the CG due to fuel transfers (by +/- 0.5%) . Hence in direct law, one would have to retrim constantly in pitch or disable the fuel transfer function.
Greybeard
I hope BEA explains how the cg moved from the automatic 38% MAC, as shown above, and in the initial report, to 29% (or was it 23?) in its latest report.
Found this reference some time ago about CG travel due to fuel
Getting to grips with weight and balance
A330 /340 starrts at page 49, inflight CG-travel page 59.
The mentioned CG from BEA makes me wonder as well, itīs that far forward form desired target CG
Aft target cg would be around 39% MAC (see page 60 of above reference) and how it is influenced by the trim-tank shows page 63.
CG target:
In flight, the FCMC controls the position of the center of gravity. It calculates the CG position and compares it to a target value, which depends on the aircraft weight. According to this calculated CG position compared to the target, the FCMC determines the fuel quantity that needs to be transferred aft or forward.
The FCMC determines the fuel quantities to be transferred to maintain the aircraft CG in a control band limited by the CG target position and CG target position +/- 0.5%. Takata, are those the 0.5% you mentioned as fuel transfer cg shift?