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You will not be able to turn up at Australian immigration, because your documentation will be checked by the airline first, and you will be denied boarding for lack of a valid Australian visa.
However, as an Australian PR, you can apply for a new RRV even if your previous one has expired. You will need to demonstrate that you've been in Australia for at least 2 of the last 5 years, or that you have other "substantial ties to Australia that are of benefit to Australia".