"External expertise and support would enable leaders and teachers to accelerate the learning progress and achievement of students," it said.
The school has changed hugely in recent years since all deaf children were given the right to a free cochlear implant, which allows many to "hear sounds" and to learn to speak English.
Many children originally stayed on the Kelston site in large dormitories, but these have now been abolished and the school now has only 23 boarding beds, used mainly for short-term live-in courses.
The school's "core" roll has shrunk from 145 at the turn of the millennium to 89. European students have plunged from 47 to 13 and the main ethnic groups are now Maori (31), Pasifika (23) and Asian and others (29). Most families are on low incomes, giving the school a decile 2 rating.
Instead, most deaf children are now in mainstream schools and are supported by either the Kelston centre's resource teachers for the deaf (368 children) or its advice and guidance service (782 children).
A Wellington parent who chooses not to use Kelston's southern sister the van Asch Deaf Education Centre, Sym Gardiner, said he and his wife pulled the ministry funding for their 10-year-old daughter Katya and used it to employ their own speech-language therapist to help Katya interpret the vibrations she "hears" through her cochlear implant.
He said the two Deaf Education Centres, now run by a single board, were "historic".
"They probably should have been out down a few years ago and started again," he said.
However, many parents want their children to learn NZ Sign Language and to identify with the "Deaf culture". Board chairwoman Rachel Douglas said Sign Language was now available to all students.
She said the board and the ministry agreed on the need for a short-term statutory manager, and agreed to appoint Johnstone who has done the role at other schools and led the official inquiry last year into Miramar Central School's isolation of children with special needs.
"Terri starts working with the centre next week, and the first four weeks will be spent scoping the work required over the coming months," she said.
A former chief executive of Deaf Aotearoa who is deaf herself, Rachel Noble, said she hoped the move would be "an opportunity for deaf education all over New Zealand".
"The focus needs to be on the rights of the deaf child and their access to language and identity in order to live productive lives," she said.
