The auditor general expects problems to arise with eight $700 million helicopters that have been purchased by the Defence Force.
In a report published on the Ministry of Defence website, Auditor General Lyn Provost says the NH90 was ordered when no air force was using it but now some problems have been detected.
These include the fact the NH90 was meant to be capable of being quickly deployed from a C130 Hercules but certification of this will be delayed.
The NH90 is also prone to damage from debris sucked into the engines.
She says when screens are fitted to fix the problem, the helicopter won't be able to operate in snow.