Christopher Luxon arrives in Papua New Guinea in June aboard a Defence Force Boeing 757, which broke down shortly afterwards. Photo: Nathan McKinnon
A business case to replace the Defence Force's often-criticised Boeing 757s is in the works, as costs to maintain them go sky high.
The pair of aircraft were first bought by the government in 2003 and are mostly used for transporting cargo around the Pacific.
They often take the role of transporting VIPs, such as the prime minister, on trade missions - but that work has cast doubt on their capability in recent years, with multiple cases of the planes breaking down.
Read more: What it's like inside the Defence Force's Boeing 757s
Official Information Act documents released to RNZ show the Defence Force has forked out just over $72 million over the past five years to keep the planes in the sky.
That money went towards both scheduled and unscheduled maintenance, as well as repair and overhaul work.
The cost of aircraft maintenance for the Air Force's fleet. Photo: Supplied / New Zealand Defence Force
A Defence spokesperson said the costs were expected as the vehicles reached the end of their service life.
"Escalating costs coupled with extended periods of unserviceability has led the government to ask for advice on possible replacement of the B757s."
The spokesperson said the Defence Force had begun market research with select aviation companies to inform a business case for the replacement of the planes.
"The next stage of the process will be the development of a business case for Cabinet consideration later this year."
The documents also revealed the cost of other aircraft in the New Zealand Air Force fleet, with the C130 Hercules having cost the most of the five-year period at just over $102 million.
The cost per flight hour for the different aircraft in the Air Force's fleet. Photo: Supplied / New Zealand Defence Force
The Defence Force said the C130 Hercules' age - 59 years - had contributed to the high cost.
It said the replacement Hercules (of which the first of five took its first test flights in the US in April) were expected to see savings in overall maintenance costs.
The documents released to RNZ also showed how fuel costs, airport charges and other associated flight costs (besides salaries) for Defence Force aircraft had skyrocketed from the 2021 financial year to the 2024 financial year.
The N190 helicopters saw the biggest increase in flying hour costs, going from $1190 per hour in 2021 to $4500 this year.
The Defence Force said those costs were outside of its control and all aircraft had seen increases over the last five years.