What was found
BDL---CO3325, CREW REPORTED DURING PREFLIGHT BURNING SMELL COMING FROM AIRCRAFT AIR CONDITIONING VENTS AND NR 2 PACK FAIL, BLEED VALVE FAIL. AIRCRAFT INSPECTED AND MAINTENANCE FERRIED TO NEWARK. AFTER ARRIVAL IN EWR, MAINTENANCE INSPECTED NR 2 AIR CYCLE MACHINE, HEAT EXCHANGER, AND ASSOCIATED DUCTING FOR DAMAGE, DEFECTS AND LEAKS, NONE NOTED. RAN NR 2 ENGINE FOR 45 MINUTES WITH NR 2 PACK SELECTED, NO SMELL OR SMOKE NOTED, DUCT TEMPERATURE BELOW 4 DEGREES CENTIGRADE COOLING SATISFACTORY. REMOVED AND REPLACED BOTH TEMPERATURE CONTROL OVER TEMPERATURE SWITCHES IAW ATR42 JIC 36-11-64. OPS CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.