THE Historical Aircraft Restoration Society building at the Illawarra Regional Airport will be closed to the public for an indefinite period to allow for the completion of internal works.
Shellharbour Councillor Peter Moran has also expressed "disgust" at claims from members of HARS that he had been "untruthful".
HARS president Bob De La Hunty said the closure was regrettable, but necessary from a safety perspective.
"[It will be] closed for a period of time - we will have a better picture in eight weeks," he said.
"We're determined to see it wrapped up as quickly as we can."
He said the decision was made by the HARS committee.
He said systems to deal with fire safety in the building would be installed during the closure.
A construction certificate allowing the program of works to improve fire safety was to be delivered to the council by yesterday morning. The closure occurs after council threatened HARS with "regulatory action" because the building, various parts of which had been occupied since 2005, did not have an occupation certificate.
In April, Cr Moran raised concerns regarding public safety after the council had confirmed that no occupation certificate had been issued on the building.
Council blamed the "disjointed" and "often unco-ordinated" construction of the various stages of the building as the reason for the lack of an occupation certificate.
However, they said expert advice had considered the fire risk to be "reasonable".
Concerns were raised again recently when Cr Moran revealed that commercial entities were also present in the building without the council's knowledge.
Cr Moran responded to comments from society spokesman Michael Hough in last week's Lake Times regarding the issue.
Mr Hough called for councillors such as Cr Moran to be more constructive and not impede the organisation's positive contributions.
"Mr Hough has labelled me as being 'untruthful' for claiming that Shellharbour Council was not aware of some of the uses of the HARS facility," Cr Moran said.
"Yet, the business paper for the council meeting on September 3 states, 'council were not aware of any businesses operating out of the HARS facility. Council officers became aware of this after Councillor Moran pointed this out'.
"[Those comments] are quite beyond the pale.
"I have no problems with HARS or Wings over Illawarra. However, after being contacted by numerous former HARS board members and being given leaked documents, I had no choice but to bring these serious issues to the attention of the relevant authorities."
The council had set an August deadline for HARS to present the construction certificate for safety works, warning that a notice of intention would be served requiring the occupants to cease using the premises.
In a report presented at this week's council meeting, council staff said HARS was permitted to sub-lease parts of the building, under the agreement with the council.
The council was working with HARS to "regularise" all sub-leases, the report said.
A report on sub-leases at the facility would be presented to council. Mr De La Hunty said Aerospace Training Services (ATS) would need to make other arrangements.