What was found
CREW REPORTED-SHORTLY AFTER DEPARTURE, FLIGHT ATTENDANT REPORTED SMOKE IN THE CABIN. NO SMOKE IN COCKPIT. CREW FOLLOWED EMERGENCY ITEMS AND QRH AND RETURNED TO SCOTTSDALE AIRPORT. AFTER START RECEIVED HS VLV 2 FAIL ON EICAS. FOLLOWED QRH AND MESSAGE DISAPPEARED. MX TROUBLESHOT FOR "OBSERVED FAULT: OIL OR FUEL SMELL/HAZE IN THE CABIN." MADE IT TO STEP 10 FINDING THE ANSWER TO BE YES, MOVING US TO STEP 28 WHICH INFORMS US TO REPLACE THE ENGINE IN 50 FLIGHT HOURS OR LESS. NR2 ENGINE CHANGE REQUIRED/IN PROGRESS.