Work on the four aircraft was conducted on-site beginning last September at an air base in Ohakea, New Zealand. A total of 30 company employees were involved in the retrofit work there.
The NH90 TTH is a medium-sized twin-engine multi-role military aircraft with a maximum speed of 186 miles per hour and a range of 497 miles. The Royal New Zealand Air Force has eight such helicopters -- four initial versions and four latest configuration aircraft.
The retrofit work was to bring the original four helicopters up to the latest standard.
Airbus did not detail the specifics of the retrofit work.
The company said retrofit programs are underway in other countries -- France, Italy, Finland, Germany and Australia -- for the NH90 TTH. Ten have already been retrofitted and 17 more are awaiting work.
The NH90 is made by NHIndustries, part of Airbus.