Allegations of safety mismanagement by an airline employee and alleged corrosion on an aircraft shown in a video that was aired by some media outlets, led to an immediate investigation by CASA.

A two-day audit of the REX Wagga maintenance facility was conducted last week by CASA which included interviews with maintenance engineering staff and management.

"The Civil Aviation Safety Authority has confirmed it has no current issues with the safety of REX aircraft," a CASA spokesman said following the audit.

The audit focused on REX's safety management system, in particular error reporting rates and processes for managing those in accordance with 'just culture' principles.

CASA also interviewed randomly selected REX maintenance staff during the audit.

"All of them said that they felt confident in reporting maintenance errors or defects and they indicated REX operated according to 'just culture' principles," the CASA statement said.

The video of REX's VH-RXN aircraft which some media outlets said showed "visible brown corrosion" was also reviewed by CASA.

"On the basis of an assessment of information provided by REX, CASA has no current concerns about the airworthiness of that aircraft," the CASA spokesman said.

"CASA would take immediate action if there was any evidence of serious safety issues at REX, or with any unaddressed airworthiness concerns in relation to a particular aircraft."

A statement by REX said it "unequivocally rejects the scurrilous allegations of a disgruntled engineer and his union that REX has a poor safety culture".

"Even though CASA is cognizant of, and has acknowledged, the effectiveness and high standards of Rex's Safety Management System and Safety Culture (having audited Rex extensively five times since February 2018), CASA should be given due credit for expending enormous effort and resources, including conducting yet another audit, to carefully examine the allegations of the union and the media," the REX statement said.

The REX statement also slammed some media outlets for "undermining REX's safety credibility in public" and said it could have damaged REX's reputation.

"If Rex had been forced to cease flying, many remote and rural regional communities permanently losing air services that are critical for their socio-economic needs," it said.

CASA said while is normally takes up to 21 days to finalise an audit report of this kind, it would expedite the completion of this report.