Four of the six New Zealand Airforce Orions have flown more than 20,000 hours, giving them some of the highest flying hours in the world.
One of the more than 40-year-old fleet has accumulated 22,623 hours.
New Zealand Airforce squadron leader Kavae Tamariki said the high flying hours are not a concern because the last mechanical upgrade - the 2001 Project Kestrel - extended the Orions' operational life into the mid 2020s.
Squadron leader Tamariki said there will come a point in time where it will not be financially viable to continue to repair the aircraft, but he said: "We're a long way from that yet."
He said: "Prior to undertaking the Project Kestrel P3 re-wing programme, the RNZAF's P3 Orions had accumulated some of the highest hours in the world fleet, and these hours were set to be the limiting factor in the life of the aircraft.
"To resolve this problem, the RNZAF initiated Project Kestrel to replace the wings with completely new wings."
This gave the fleet "a new lease on life" and extended their operational life into the 2020s, he said.
A total of 2380 flying hours per year are shared between the six Orions.
Deputy Secretary of the Ministry of Defence's acquisition division Des Ashton said many similar planes - often commercial planes - are repaired over their lifetimes, but "to be fair they don't engage in low-level work that the P3 do".
This year the Orions have been involved with numerous search and rescue missions.
The most high profile ones involved helping with the rescue effort of the Soamoan tsunami and Tongan ferry disasters in October and August.
Orions were also regularly called out to help sailors who ran into trouble - an Orion was sent to assess the situation and divert a cruise liner when Swiss sailor Bernt Luchtenborg's yacht Horizons got into trouble in November.
An Orion was also needed to locate three Kiribati fishermen 4000km north of
New Zealand in August; in April an Orion was sent to ensure the safety of
sailors onboard the yacht Boundless, 370km north-east of New Zealand.
The Orions are currently undergoing a $352 million upgrade to their navigation and communication systems.
Ashton said the upgrade will improve the intelligence, surveillance and reconnaissance capability to support the government and will ensure the systems meet future regulatory requirements.