Air New Zealand hopes to get one of its grounded Boeing 787s back in the air by the end of the month with the second following a few weeks later.
The Kiwi carrier was forced to ground the two jets in April after checks revealed problems with some of the airline’s Rolls-Royce engines.
It is one of a number of airlines caught up in global problems affecting several hundred 787 engines which have prompted action by the US Federal Aviation Administration and European safety agency EASA.
The problems have caused several engine failures and “numerous” reports of engine inspections finding cracked blades resulting in unscheduled engine removals, according to the FAA.
Air New Zealand was forced to reschedule services and announced a small number of cancellations in April as it performed checks required by EASA and Rolls-Royce on engine compressors in Trent 1000 Package C engines.
The two Boeing 787-9 Dreamliners were removed from service while engines underwent maintenance work at a Rolls-Royce facility in Singapore.
With those engines heading home, an Air New Zealand spokeswoman confirmed the timetable for returning the Dreamliners to service.
Air NZ undertook the engine checks after problems with the Package C engines prompted EASA and Rolls to reduce the number of landing and take-off cycles between inspections.
The FAA followed with an Airworthiness Directive reducing the maximum flying time affected 787s are allowed to be away from a suitable emergency airport from 330 minutes to 140 minutes.
The US regulator said it had been told by Boeing that Rolls-Royce had determined that intermediate pressure compressor stage 2 blades have a resonant frequency that was excited by airflow at high thrust settings under certain temperature and altitude conditions.
The vibration caused by this could result in cumulative fatigue damage that could cause blade failure and engine shutdown, it said.
Air New Zealand Chief operational integrity and standards officer David Morgan said in April the airline was fully compliant with the directives of EASA, the FAA and Rolls-Royce.
“Like Air New Zealand, aviation regulators prioritize safety over everything else and EASA and FAA have taken a very conservative approach in the checks and restrictions they’ve put in place around these engines,’’ he said.
“Customers traveling on our Dreamliner aircraft can be very confident in the integrity of the engines.”