where on the plane is the “R fixed window sensor” ? directional-to the right or to the rear? or row identified?
I’d guess that’s a windshield heat sensor for anti icing.
From the NBC report: “An “FCU” refers to a unit in cockpit the pilot uses to input instructions into the flight computer. “SEC3” refers to the computer that controls the spoilers and elevator computers of the plane. The fault messages indicate there could have been problems with the plane’s controls and computers, critical to controlling the aircraft.”