The full fleet of Beech aircraft that operates in and out of Blenheim Airport is running as usual, Air New Zealand says.
The planes were grounded after hairline cracks were discovered in the tail section of three planes.
Air New Zealand spokeswoman Marie Hosking said the normal flight schedule for passengers flying in and out of the airport had been in place since about mid-October.
The fleet of 18 Beech 1900D aircraft operated by Air New Zealand subsidiary Eagle Air was grounded on August 7 when engineers found cracks.
The full fleet was back in operation, Ms Hosking said.
The normal scheduling for the regional fleet allowed for two aircraft to undergo planned maintenance at any time.
- The Marlborough Express