European regulators have certificated the Airbus A320 twinjet featuring sharklet wing-tips, initially for the CFM International CFM56-powered airframes.
Other members of the family - including those with International Aero Engines V2500 powerplants - are yet to secure approval.
The clearance has been granted by the European Aviation Safety Agency but Airbus says it expects to obtain US FAA certification "very soon".
All four of Airbus's final assembly lines for the A320 family - located at Toulouse, Hamburg, Tianjin and Mobile - will be building sharklet-equipped versions of the aircraft, says the airframer.
AirAsia is set to take the first sharklet-equipped A320 before the end of this year.
Airbus executive vice-president for programmes Tom Williams says the fuel savings achieved during test flights has been "better than we'd anticipated" at around 4% for long sectors.
Some 600h of airborne tests, lasting nine or 10 months, are being conducted for the sharklet certification. Airbus says the approval for the remaining aircraft and engine combinations will follow "in the coming months".