bnt is right. There are weight restrictions at the ETOPS entry point, intended to require reduced power on the remaining engine to protect it for the diversion. It's warm temperature limiting, and as most AirNZ long haul flights cross through equatorial areas,this makes it even worse. The 140 min limitation would normally allow all non Nth/Sth America routes to be flown, so this weight/temperature problem is major.
(AKL-HNL just fits, it needs 138min!) AirNZ are really unlucky in this Trent crisis, because they bought and operate these planes for very long haul overwater flights, and it's hitting them hard. One plane (Trent 1000 TEN) unrestricted. Two Grounded. All the rest subject to above. Meanwhile, there is a warehouse near the RR facility in Singapore slowly filling up with the backlog of unserviceable Trents. Bosses at both RR and AirNZ, and no doubt many other operators not getting much sleep!