Air New Zealand services could be disrupted for the next two years, as 17 of its aircraft are checked for possible microscopic cracks in the engines' fans.
In July, engine manufacturer Pratt and Whitney announced up to 700 planes worldwide need to be inspected, affecting maintenance schedules.
Air New Zealand said the 17 A320 and 321 NEO aircraft served Australia, the Pacific Islands and domestic routes.
Chief executive Greg Foran said most customers would still fly on the same day, but some on international flights will move a day either side of their original booking.
The airline would have up to four planes grounded at any one time and was looking to lease additional aircraft.
Foran told Morning Report about 329,000 people would see little to no impact between now and April, but almost half would be affected in other ways which could include a different plane or seat changes.
"About 150,000 people will see a change and that may be a slight retiming on the flight that could be anything from sort of an hour to a day, and we'll offer those people an opportunity to get to where they want to or if they doesn't suit them anymore, a refund."
Direct flights from Auckland to Hobart and Seoul would also be paused from April 2024.
"The pause on flying to Seoul will allow more resiliency when the Trent-1000 engines that power our 787 fleet go for regular maintenance due to potential issues with the availability of spare engines from Rolls Royce to cover the maintenance period," Foran said.
"While both routes have performed well, we need to ensure we can deliver a reliable service across the rest of our network and get customers on our most in-demand routes to where they need to be."
Foran said a halt on flights to Hobart and Seoul was due to fewer customers.
"The reason we've picked those routes is they're the ones that tend to have less impact on customers, so we've taken a postponement, a pause if you like, of six months on those routes and we won't be flying them from sort of April till November next year."
Impacted customers did not need to contact Air NZ - they would be contacted in the coming weeks.
"We reach out to the customers and advise them of the retiming if there is a retiming of their flight and any changes," Foran said. "What we find when this happens is it's not the first time, is that by far the majority of people still want to travel, they want to get to where they want to get to, they're on vacation, they're going to see family, wedding or whatever and we do our best to accommodate that - but you know, it's unfortunate."
Foran said it was not the news the company hoped for, after it announced earlier this year it had purchased new aircraft to add capacity and assist in meeting ongoing strong demand.
"Although those new aircraft are still due to arrive - two new ATRs in late 2024/early 2025, two new A321NEOs in early 2025 together with two domestic A321s and eight B787s being delivered between 2024 and 2027 - these network and schedule changes have been required to manage an issue that no one expected just a few months ago.
"We will continue to do everything we can to ensure stability across our network."
Foran said despite there being an engine centre in Christchurch, the engines had to be sent to Connecticut and Singapore.