Defence Minister Wayne Mapp says a much-delayed upgrade to five Air Force Hercules has taken "a heck of a long time", but the project is back on track.
A deal was reached with contractor L3 Communications for the Government to take over subcontracting after Air New Zealand subsidiary Safe Air pulled out.
It is five years since the $254 million project was signed off, and while work has taken place on two aircraft, the Air Force has rejected both planes due to of software bugs.
Dr Mapp says the two planes will be tested and evaluated by the end of the year, and work on a third Hercules will begin early next year.
RadioLIVE