Airbus has introduced a temporary revision to A321neo flight manuals intended to prevent the possibility of the aircraft reaching excessive pitch attitudes.
The European Union Aviation Safety Agency has disclosed that the revision follows analysis of the re-engined type's elevator and aileron computer.
It has not elaborated on the situation beyond stating that "excessive" pitch could occur under certain conditions and "during specific manoeuvres".
EASA cautions that this could result in "reduced control" of the aircraft.
Airbus has issued temporary revisions to the aircraft's flight manual incorporating operational limitations.
EASA has ordered operators of the A321neo to amend the flight manuals accordingly, within 30 days.
The order covers both the CFM International Leap-1A and Pratt & Whitney PW1100G versions of the aircraft.
Airbus has issued seven relevant temporary revisions to the flight manual, on 21 June and 10 July. EASA says the safety measure is an interim action and could be followed by further requirements.