GE Aerospace showed off its Boeing 747 "flying laboratory" in July. It's being used to test the engine of Boeing's future 777X.Carl Court/Getty ImagesGE Aerospace uses a decades-old Boeing 747 to test and help certify new commercial jet engines.The aircraft is filled with cabling, metal data boxes, workstations, and passenger recliners.Business Insider toured the unique 747 at an airshow in July and spoke with GE's chief test pilot.Leading Ameri…