Europe's safety authority has formally issued initial proposals detailing modification work required on Airbus A380 wing-rib feet, intended to resolve a cracking issue.
Operators had previously been ordered to conduct repetitive inspections of the wing structures and, if necessary, put corrective measures in place.
Airbus has since been developing a permanent fix for the problem, which involves introducing horizontal stiffeners in the vicinity of certain ribs.
It also requires modifying rib-feet booms with resized versions manufactured from a different, more robust, grade of aluminium, and replacing two metallic ribs - numbers 48 and 49.
In its proposed directive to operators the European Aviation Safety Agency refers to 14 separate service bulletins - some issued in mid-December, others yet to be - detailing the work to be carried out.
The document focuses on modification of hybrid rib booms to "maintain the structural integrity" of the type's wings.
EASA is proposing that some of the work be carried out as early as 700 cycles.
Further work must be accomplished before the aircraft logs 17,300h or 25,900h - depending on whether certain modifications have already been made during production - and the remainder within six years of the aircraft's receiving its certificate of airworthiness.
EASA is yet to finalise the directive and is seeking comments on the proposal until 13 May.