What was found
CREW REPORTS RIGHT GENERATOR FAILURE. APU BEING USED & APU INLET DOOR OPEN. APU AUTO SHUTDOWN AT 16500 FT 310K & AGAIN AT 14500 FT 250K IDLE POWER. [SUP 06-06-07] NR 2 ENGINE IDG WAS REPLACED, BUT CAUSE OF W-U WAS APU AUTO SHUTDOWN. AFTER TROUBLESHOOTING, APU DIFFERENTIAL PRESSURE SENSOR WAS CLEANED AND RESECURRED. FOLLOW-UP VERIFICATION FLIGHT CONFIRMED APU OP AT ALTITUDE. PLANE RETURNED TO ETOPS SERVICE.