A plane that had to make an emergency manoeuvre when it lost cabin pressure is being repaired and will be put back into service.
Oxygen masks were deployed on the flight from Wellington to Auckland on Friday morning.
The Transport Accident Investigation Commission is looking at what caused the incident, in which the plane was brought down from 33,000 feet to 7000 feet in minutes.
In a statement, Air New Zealand says its engineers were unable to find anything wrong with the aircraft's pressurisation system but it is being replaced as a precaution.
The aircraft will then return to service.
The airline previously said one of the 76 passengers might have hyperventilated during the incident.