Only HARS members involved in construction work will be allowed into the society's building at Illawarra Regional Airport after Shellharbour City Council issued a new order on the facility.
The Historical Aircraft Restoration Society voluntarily closed the building to the public last month to allow works on the facility to be completed and have fire safety systems installed.
While the building - which does not have an occupation certificate - is closed to the public, HARS members have still been allowed access.
This week Shellharbour councillor Peter Moran raised concerns that the training organisation Aerospace Training Services (ATS) was still being allowed into the HARS building after he had been informed students were being signed in as "associate members".
HARS president Bob De La Hunty said ATS was no longer using the building and had made other arrangements as they had been required to do.
Despite this a Shellharbour council spokeswoman confirmed the council had issued "a Notice of Intention to give an order - or intent to order to ensure a developer - in this case HARS, ceases to use its museum and associated hangars until it receives an occupation certificate".
The HARS hangar is used to store the region's aeromedical helicopter, although the aeromedical team is based out of a separate "temporary facility" at the airport.
Mr De La Hunty said whether the helicopter could legally remain stored in the HARS premises would be clarified when the building's independent certifier met with the council on Tuesday.
Meanwhile, Shellharbour City Council is calling for community support to back its application to fund a new aeromedical facility at the airport. The proposal has been shortlisted for the Restart NSW Illawarra Infrastructure Fund.
The NSW government is hosting an online community engagement page to gauge the level of support for the listed projects to assist with the final decision.