A career educationist and experienced private school inspector, Ray Barrett is supposed to be in retirement, but he has agreed to take on the top job and help the Greenacre school get back on track.

And while the appointment of Dr Barrett was a surprise choice for some, a spokesman for the school board said he was chosen for his qualifications and experience, and his religion didn't come into it.

When he first met parents, one asked Dr Barrett how he would deal with the issue of Islamic studies. He told the parents the same way he deals with HSC physics - another subject he knows nothing about - rely on the experts.

''This is a top-performing school and you will find graduates that are doctors, lawyers and dentists,'' said Dr Barrett ''The parents are aspirational. They want their kids to achieve and take the next step in life.

''This school is no different to any other, they have universal values and I want to help the kids to be the best they can.''

Malek Fahd has almost 2500 students, across three campuses - more than 2000 are at the Greenacre campus - and there is a long waiting list which has been frozen because the school has exceeded its capacity. It has received most of its funding from state and federal government grants. But it has also been the subject of controversy after the previous two principals were removed and allegations that the school had been operating for profit.

The state government stopped funds to the school and ordered it repay the funding it had received since 2010. The federal government also ordered an audit of the school after allegations of mismanagement.

But Dr Barrett said auditors and investigators have spent weeks going through the school records and so far they have found everything to be in order.

Dr Barrett, who has turned around troubled schools, including a Muslim school in Canberra, said his job is to restore confidence. He said the most important thing he had learnt is that ''under the surface we are all the same''.