Engine issues that have hit Air New Zealand Dreamliners could stretch for another year, forcing the airline to take new steps to get beyond what its boss says has been some ''ropy'' service.

The airline faces a $30 million to $40 million hit to its net profit in the current financial year as a result of leasing more planes and changing schedules on some long-haul routes to Taipei, which is about to start, Buenos Aires and Haneda in Japan.

Chief executive Christopher Luxon said the airline would take more ''assertive'' action to restore reliability.

During the last nine months tens of thousands of passengers have had flights cancelled, rescheduled or faced flying in different planes as a result of new safety requirements for Rolls-Royce Trent engines used on most of Air New Zealand's Boeing 787-9 aircraft.

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Luxon told the Herald the fuel pipeline rupture last September and severe weather had been disruptive but it was the engine issue that had hit hardest.

''We want to be able to cauterise this risk and deliver a solid reliable service that people have come to know.''

The airline today announced pre-tax earnings of $540 million, the second highest profit in the airline's history, and it will pay staff an $1800 bonus.

Net profit after tax grew 2.1 per cent to $390m.

The $1800 will be paid to about 8500 mainly union staff out of a workforce of 12,000. Those on short-term incentive programme have their own bonus structure.

The Rolls-Royce Trent 1000 Package C engines used on most of the airline's Dreamliners are part of a global alert and it could take 12 months to work through the problems, he said.

''As we look forward we can see there is a global production backlog starting - it means those engines when they come off planes are taking longer to get inspected. As a consequence we can't keep going as we've been going.'

Read more: Air NZ's Dreamliner issues

'He said the schedule changes and the leased planes would mean up to four Dreamliners could be out of action at one time and schedules being maintained.

''Let's make sure we can deliver the core of our schedule so people can trust it.''

Earlier in the year Air New Zealand used Portuguese charter airline Hi Fly to plug gaps and now has leased an ex-Singapore Airlines 777-200 and Eva Air 777-300. The third leased plane would be a sister aircraft to the Singapore Airlines aircraft.

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