An Airbus spokesman said it is "in discussions with customers about delivery schedules" on a case-by-case basis.
Not all of the engines are affected by the issue, though the spokesperson declined to say how many.
Of the 113 Pratt-powered aircraft in operation worldwide, about 30 per cent are equipped with either one or two faulty engines, the planemaker said in an emailed response to questions from Bloomberg News today.
It's impossible to overestimate the importance of the A320 for Airbus. "IndiGo has only three such affected aircraft".
IndiGo and GoAir are the two domestic carriers that operate A320 neo planes powered with P&W engines.
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The A320neo's planned 2015 entry into service was pushed into 2016 because of GTF issues, and both Airbus and Bombardier have blamed Pratt for A320neo-family and CSeries aircraft delivery delays as Pratt & Whitney struggled to ramp up production as fast as needed and as fixes to address reliability and durability shortfalls were simultaneously introduced.
"This year is "2017 Take II" by the looks of it", Morris said. Airbus thus delivered only 181 A320neo instead of 200 initially expected.
Pratt implemented an engineering change in mid-2017 that was meant to improve the durability of the seal, with the new engines fitted to aircraft from December 2017, but the modified engines "did not perform as anticipated", the company said.
If the latest problem leads to penalty payments to IndiGo and other customers, it wouldn't be the first time Pratt was on the hook financially.
A total of 113 planes in the A320neo family, used by 18 airlines, are now in service that are equipped with the engines. In late January and early February, four of these modified engines "did not perform as anticipated", it said. Pratt won several key orders late in the year as the earlier issues subsided, and executives at Airbus and United Technologies said the manufacturer seemed to be moving on from a hard chapter.
"Following a problem identified on a limited number of recently delivered Pratt & Whitney GTF engines involving the rear hub of the high-pressure compressor rotor, Airbus and Pratt & Whitney are reviewing the situation", writes the aircraft manufacturer with no further precision.