Flyboy2, sorry you had 2 wait this long. Think it is the accident you are referring 2.
Either in '69 or '70, my dad was asked by his boss (think it was with United airways) to do a route proving flight with a DC3 into Nelspruit (FANS, before they extended the runway. Then it still ended at the "rapid exit"). The flight ended without any events, except that my dad refused to take the DC3 back there, stating that the airfield is unsuitable for the Dak. The air force heard that a civvy dak had been into FANS and decided to go there on the next air show, but unlike my dad's dak, this one had pax onboard. The runway was to short...
I'm still jogging my dad's memories/logbook and will try to give you a more specific date.