Airbus has urged A321neo operators to implement a temporary center-of-gravity (CG) limitation to eliminate an already-remote risk of an excessive pitch-up condition while it finalizes a software update that addresses the issue. The European Aviation Safety Agency (EASA) on July 17 mandated the CG restriction for European operators, requiring a flight manual amendment detailing the restrictions by the end of August.
The issue, discovered during development tests, affects any A321neo with elevator aileron computer (ELAC) unit software version L102 installed. The excessive nose-up attitude can occur when four conditions are met: an aircraft's CG is greater than 37% aft, it is in “flare mode” at an altitude of 100 ft. or below, flaps are fully extended, and the crew initiates a go-around with a sustained nose-up pitch input of 65% or greater.
Airbus in June told operators to limit A321neo dispatch conditions to 37% aft CG. This removes one of the four factors, eliminating the risk.
Airbus emphasized that is has no reports of the issue happening in service. The manufacturer also said the “anomaly" would not prevent the pilots from controlling the aircraft.
"Under the combination of these specific conditions, the aircraft might have entered a dynamic pitch-up situation, which even then the crew could react to immediately,” Airbus explained. “Under these conditions, there is absolutely no aircraft automatic take-over from the crew’s manual inputs.”
The European manufacturer is working on a software update, ELAC L103, and plans to have it ready by mid-2020. It has been working with customers since the issue was discovered, and the limitation is expected to be adopted by operators globally, even if regulators do not mandate it.
"There is no need for modification to existing operational and training procedures,” Airbus said, adding that it “supports” EASA’s decision to mandate the temporary CG limitation.
Airbus has delivered about 190 A321neos. It is not clear how many have the affected software version.