SYDNEY (Reuters) - A Qantas jumbo jet bound for San Francisco was forced to return to Australia on Saturday after a  technical issue  90 minutes into its flight, the airline said. Engineers were inspecting the Boeing 747 after it landed at Sydney s Kingsford Smith airport, a Qantas spokeswoman said, declining to say how many people were aboard. No injuries were reported.  We understand delays can be frustrating for our passengers but we ll always put safety ahead of schedule and our teams are doing everything they can to get passengers back on their way,  she said. Passengers were told that flight QF 73, which departed at 2.10 pm local time, had been turned back because the autopilot wasn t working, a passenger told Australia s ABC News.  The flight got ridiculously bumpy, and the seatbelt sign never got switched off,  the passenger said.   