New Zealand's Defence Force planes are getting more expensive to keep in the sky.
A Royal New Zealand Air Force C-130 Hercules aircraft. Photo: Supplied / NZDF
Official documents released to RNZ show the forecast cost for repairs and maintenance in the current financial year for the Hercules and Orions is expected to be $52.4 million.
Based on previous documents, that would be a record annual spend.
Defence could not give any projections for future financial years because the data has not been calculated yet.
In June, RNZ reported that Defence had spent around $360m on keeping the two fleets fit for purpose over a decade.
The 1960s Hercules and Orions are coming to the end of their operational lives and are some of the oldest platforms still in use by Defence.
The Orions had five engine failures over 15 days last year because of propeller malfunctions, while the Hercules have also had propeller leaks and faulty oil guages.
Defence Minister Ron Mark has been well aware he has to find replacements.
Last month, he announced his first big purchase, the P8 Poseidons, which would replace the Orions from 2023.
But a decision on what would replace the Hercules fleet still needs to be made.
Aviation expert Peter Clark said that was a pressing purchase and should have been made 20 years ago.
"Our Air Force is fantastic and our engineers and their capability - they are exemplary in what they do in keeping those aircraft in the air - but they are old, it is like driving a bloody Model T," he said.
He said there were a handful of replacements Defence could look at buying, including the updated C130-J Hercules.
"I would say even making a decision late this year, we won't see an aircraft fully installed into our Air Force for six to eight years time," he said.
Mr Clark expected a decision to be made in the current government term.
Victoria University Professor Robert Ayson said the government would not want to continue to have costly bills for repairs and maintenance.
"Mr Mark wants to be seen as a defence minister of action and so I think this would be part of what he would seek to deliver," he said.
The minister has said he wanted to wait for the Defence capability review to be released in November before taking the next steps on replacing the Hercules.
In the meantime, he has been reassured the current Orions and Hercules were safe to fly.