PA39, while doing my instrument rating in Port Macquarie in 2000, every Friday I would watch a PA31 load up and head eastwards for YLHI. I was told that as far as the passengers knew it was an RPT flight but that if you looked at the actual paperwork it revealed that it was a cost-share private flight. A quick look at the regs at the time revealed that you had to hold a mainland alternate to fly to YLHI and a Chieftain certainly would not do that with the loads they were carrying.
It was a strange thing that every time CASA paid a visit to Port Macquarie, that particular aircraft, which incidentally was one of the higher time Chieftains in Australia, was always absent from the field despite it not being a day for which it was scheduled to fly. I was told that the operator or a person associated with the operator was the very same person previously connected with Seaview.
It would not have taken much for CASA to have unearthed the commercial arrangements behind those flights but somehow they never got around to that.