Meanwhile back at the airport, Robey tried to get more information about the unidentified flying object and its location. Valentich reported that it was now coming at him from the southwest. About 29 seconds later, he stated that he was experiencing engine problems and was going to proceed to King Island. After a brief silence, he came back and said "it is hovering and it's not an aircraft." This was followed by 17 seconds of unidentified noise, later described as being "metallic, scraping sounds." Then all contact with Valentich was lost at 7:12 p.m.
(Via The Anomalist.)
Greg Bishop might justifiably ask why Valentich's engine didn't stall in the UFO's presence.