Airbus has determined that the A320neo is potentially vulnerable to an angle-of-attack protection weakness which could result in excessive pitch attitude under certain circumstances.
The condition is "different" from the excessive-pitch anomaly recently discovered during analysis of the larger A321neo, says the European Union Aviation Safety Agency, although it appears outwardly similar.
EASA stresses that the condition has never been encountered during A320neo operations.
But it says that a "reduced efficiency" of the aircraft's angle-of-attack protection under certain flight configurations, and in combination with specific commanded manoeuvres from the crew, could lead to excessive pitch and higher workload.
The scenario has been uncovered during analysis and laboratory testing of the A320neo flight-control laws.
Airbus has developed temporary revisions to the A320neo flight manual to address the condition, and EASA has ordered operators to amend their manuals accordingly.
The changes limit the centre-of-gravity envelope for the aircraft. Airbus has also issued loading recommendations.
Both the CFM International Leap-1A and Pratt & Whitney PW1100G versions of the aircraft are affected.
EASA has opted for quick implementation of an airworthiness directive, requiring the changes within 30 days of 14 August, postponing the commentary period until after publication.
Its measures follow the discovery of a behavioural issue with the elevator and aileron computer on the larger A321neo which also affected angle-of-attack protection under particular conditions.
EASA has previously issued similar preventative instructions, involving flight manual changes and balance limitations, and has identified the specific computer units affected.
Airbus is working to develop a flight-control law amendment for the A321neo which will become available next year.