Pratt & Whitney has proposed dropping an engine modification that grounded almost a dozen Airbus SE A320neo jets as it works to fix the latest glitch plaguing the program, according to people familiar with the plan.

The move involves replacing a new engine seal with an older one scrapped amid durability issues, the people said, asking not to be named because it hasn’t yet been made public. That should prevent delivery delays and limit the cost to Pratt and Airbus, though a permanent fix will still be required.

Pratt, part of United Technologies Corp. spent $10 billion developing its fuel-efficient geared turbofan model for short-haul jets, only for the engines to suffer a series of setbacks that marred their commercial introduction and led to delivery delays. While the fix should help persuade investors that the turbine—and the A320neo—isn’t about to suffer a major crisis, reverting to the original component, itself flawed, won’t be sufficient in the longer term.

Pratt competes with a joint venture of General Electric Co. and Safran SA to power the Airbus narrow-body plane, with the ground-up GTF development having sought to cement its status as a supplier of choice on the most widely flown type of aircraft.

The European Aviation Safety Agency has signed off on the corrective measure, which involves the elimination of a new so-called knife-edge compressor seal, the people said. Airbus referred requests for comment to Pratt & Whitney, where a spokesman couldn’t be reached out of hours. EASA spokesman Dominique Fouda didn’t immediately respond to phone and email messages.

The seal issue grounded aircraft where both engines featured the new seals, including three operated by IndiGo, India’s largest airline and the biggest A320neo customer.

In order to get planes flying again, all aircraft have now been fitted with at least one unmodified engine, making them compliant with an EASA airworthiness directive, one of the people said. Extended operations over water won’t be permitted for those aircraft.

United Technologies Chief Executive Officer Greg Hayes is set to address the seal issue later Wednesday, according to the people. Airbus shares advanced to a high for the trading session and were priced up 0.8 percent at 97.73 euros as of 12:47 p.m. in Paris.

‘Annoying’

Almost a third of the 113 Pratt-powered A320neos in operation are equipped with one or two of the engines with the latest flaw, Toulouse, France-based Airbus said last week.

Germany’s MTU Aero Engines AG, a partner with Pratt on the GTF, played down the seal issue Wednesday, labeling it “annoying” but unlikely to affect long-term demand it puts at 15,000 units. While the A320neo will be the turbine’s biggest market, the model will also power the Bombardier Inc. C Series, Mitsubishi Regional Jet and Embraer SA’s new-generation models.

“The engine will be a success,” MTU Chief Executive Officer Reiner Winkler told analysts in Munich. “Airlines won’t be discouraged by such short-term issues to change an investment decisions that will have an effect for 20 to 25 years.”

Winkler said GTF production should double this year from 374 engines in 2017, suggesting that 2018 output may come close to the 800 units targeted.