What was found
LOWER AFT BODY OVERHEAT LIGHT ILLUMINATED AFTER NR 2 ENGINE BLEED OPENED AFTER TAKEOFF, APPROX 1500 AGL. WENT THROUGH AOM ABNORMAL PROCEDURE, OVERHEAT LIGHT EXTINGUISHED APPROX 1-2 MINUTES AFTER NR 2 ENGINE REDUCED TO IDLE. OVER NEXT 15 MINUTES, SLOWLY INCREASED NR 2 TO APPROX 85 PERCENT N1 AND A BURNING FIBERGLASS SMELL OCCURRED IN COCKPIT. DECLARED EMERGENCY, RETARDED THROTTLE NR 2 TO IDLE. FOUND RUPTURED 6TH STAGE BLEED AIR DUCT ON NR 2 ENGINE. REMOVED AND REPLACED WITH SERVICEABLE PART PER M/M 71-00, OPS CHECK NORMAL. ALSO, REPLACED FAULTY NR 2 ENGINE BLEED AIR SHUT OFF VALVE PER M/M 36-12, OPS CHECK NORMAL. RAN ENGINES, NO OVERHEAT INDICATIONS.