What happened to Uncle Petrie?
Uncle Petrie was planned as a “Gramps” type character, but he didn’t work out and was quietly dropped from the series without explanation after fifth season (although he appears out of nowhere in the sixth season story “In Case of Emergency,” which may have been filmed as a fifth season episode and then postponed). In the first episode with Petrie, it was explained he was just there temporarily to help Paul get started on the farm.