Seven Eagle Airways planes remain grounded while cracks in their tail areas are repaired.
All of the company's 18 Beech 1900D aircraft were grounded on 7 August when a crack was found in the tail of one during routine maintenance.
After the fleet was checked, four were deemed fit to fly; the other 14 stayed grounded while the manfacturer was consulted about any maintenance work.
Eagle general manager Carrie Hurihanganui says seven more planes have been given the go-ahead to fly, with remedial work continuing on the other seven.
Eagle Airways, an Air New Zealand subsidary, operates the 19-seater Beech 1900D planes out of 20 domestic airports.