Mmmm ....
Yes ... those 500's belong to Vowell Air Services (they're still in their blue paint scheme which didn't change till the following year) and it looks like they are at the Mount King Base camp in Antarctica. I vaguely remember it being some 400 Nmls from Mawson. I think the year might have been was 1976/7.
The bare U/C legs was to allow for easier 'role change' when removing the 'pop out float' kits and vice versa (anyone who has done this job knows what I mean!!) and to make it easier to tie the a/c down on the ship and on the 'Ice'.
Vic Barkel was the lead pilot (he came over to Vowells when they got the contract) he was 'The Man' in the Antarctic Divisions eyes ... I seem to remember Lt Col. Alf Argent (ANARE) also was there as well as Bill English and I think(?) Brian Miller.
The Pilatus Porter was sent by 'Forrester Stephens Aviation' ... and flown by Dick Trippett (ex Aus Army) their Engineer was I seem to remember a (Swiss German ?) named Holger ????? ... oh didn't we have lotsa fun getting the drift snow out of it after a Blizzard struck ...
Anybody there then will probably still be nauseated by the smell of a Frey Bentos Steak & Kidney pie anywhere near them!! (and you DID have to have been there !!).
I think(?) the 500 behind the intrepid explorer is VH-PMY ... the others will be VH-BAG and VH-BAD.
Ahh the memories come flooding back
Edit: might have possibly been the 77/78 expedition .. time blurs all memory ..
largish scruffy bloke in centre frame might be **** Robinson/Robertson (???) who was the senior aircraft engineer on site ???