What was found
(CAN) DURING CLIMB, CREW NOTICED A SMELL OF SMOKE IN THE FLIGHT DECK. CREW DONNED OXYGEN MASKS AND COMPLETED THE (OXYGEN DRILL). UNSCHEDULED LANDING COMPLETED. ENGINEERING ONSITE INVESTIGATION CONFIRMED FAILURE OF THE AFT AIR CYCLE MACHINE (ACM). THE AFT ACM WAS REPLACED AND THE AIRCRAFT RETURNED TO SERVICE WITHOUT FURTHER INCIDENT. ACM HAS BEEN DISPATCHED TO THE MFG FOR REPAIR/OVERHAUL WITH A REQUEST TO PROVIDE A STRIP REPORT. (TC NR 20080228003)