Airbus is suspending its sharklet retrofit programme for A320s which do not have the reinforced wing developed to support the modified wing-tips.
All A320s currently in production feature, as standard, a newly-strengthened wing which gives customers the option of having sharklets fitted - either on the assembly line or through a simple swap of the wing-fence during routine maintenance.
Airbus has also been examining a possible programme to retrofit older A320s - those without the current wing standard - with sharklets.
But this would have required extensive changes to the wing and longer downtime, and Airbus chief operating officer for customers John Leahy said, during the Paris air show, that this retrofit plan has been "paused".
"We would like to do it," he says. "But we do not have a business case that works."
He says the retrofit market involves dealing with aircraft which are already substantially through their useful life, meaning the benefits can only be "advertised" over a much shorter period compared with new aircraft.
When combined with the complexity of the modification, he says, the economic justification fails. "It's volume of business," says Leahy, adding that the case "didn't add up".
The airframer had previously signalled that a retrofit programme could have been launched earlier this year if enough customers committed.
US carrier JetBlue Airways has been engaged in an extensive retrofit of the tips to A320s which have sharklet-compatible wings.