What was found
ON FLIGHT 3509, AT CRUISE AND FL 360 PAX AND CREW DETECTED THE ODOR SOMETHING BURNING. AT THIS TIME BOTH VS INDICATION +4000 -4000 FPM AND 'ALT ON BOTH PFD AIRSPEED DECREASING. AT ABOUT FL 320 ALL SYSTEMS BACK TO NORMAL. AIRCRAFT REMOVED FROM SERVICE. REMOVED WATER FROM CAPT AND F/O PITOT-STATIC MOISTURE DRAIN/TRAPS IAW WC 34-600-01. CAPT AND F/O ADC INDICATIONS OP CHECK GOOD IAW AMM 34-15-00. FOUND AFT CABIN FLASHLIGHT WITH MELTED MARKS. REPLACED AFT FLASHLIGHT ASSEMBLY IAW AMM 33-50-16 OPERATION CHECK GOOD NO BURNING ODOR AT THIS TIME. PRESSURIZATION OPERATION CHECK GOOD AT THIS TIME. AIRCRAFT RETURNED TO SERVICE.