UPDATE 1-Air New Zealand says 14,000 passengers to be affected by Rolls-Royce engine issue

(Adds background on engine issue, details on cancellations)

Nov 18 (Reuters) - Air New Zealand Ltd said on Monday about 14,000 customers would be affected by cancellations this summer because of ongoing Rolls-Royce engine checks on its Boeing 787-9 aircraft.

The national carrier, which has 10 Trent 1000 engines on its 787-9 fleet, said the schedule changes were "now unavoidable", adding that further changes may also be needed.

Rolls-Royce has been struggling to fix an issue on blades on the TEN variant, causing more and more passengers face disruptions due to checks and repair work.

"Rolls-Royce does not have any replacement engines available while maintenance work is undertaken and has advised Air New Zealand there’s significant wait for repair service," said a statement by the airline.

Air New Zealand will suspend its twice-a-week seasonal Christchurch-Perth service - hitting 61 flights - and its second daily Auckland-Perth service from Dec. 10 until Jan 5, 2020.

"Going into the holiday season we're acutely aware how important travel is to our customers, and our schedule changes are designed to keep cancellations to a minimum," Air NZ's Senior Manager Customer Care and Communications Doug Grant said in a statement.

Rolls-Royce's cost to fix the issue jumped by another 800 million pounds ($1.02 billion), as the aerospace group promised to spend more on parts and replacement engines to reduce the time aircraft are grounded while turbine blades are replaced.

($1 = 0.7815 pounds) (Reporting by Nikhil Kurian Nainan in Bengaluru; Editing by Peter Cooney and Tom Brown)