The Civil Aviation Safety Authority has extended restrictions on Jabiru-engined aircraft.
CASA imposed restrictions on 22 December last year, which were set to expire on 30 June.
"Collaborative efforts involving Jabiru, Recreational Aviation Australia and the Sport Aircraft Association of Australia have been ongoing and productive, and it is hoped that an effective response to the problems will soon be identified," the regulator's announcement says.
"In the meantime, with particular regard to the safety of passengers and others who may have little (and in some cases no) knowledge of, or effective control over, the risks to which they may be exposed, CASA will be re-issuing the operational directions as from 1 July 2015, pending the identification and implementation of effective remedial actions.
"Therefore, the operational limitations imposed in December 2014 will continue to apply as from 1 July 2015."
CASA has, however, relaxed one of the requirements. Pilots were not permitted to carry a passenger unless that passenger had signed a statement acknowledging the risk within 28 days before the flight. That time limit has now been extended to three months.