What was found
NOTIFIED BY CREW. BURNING SMELL IS BACK, RETURNED DURING DESCENT, VERY STRONG THRU 5000 FEET TO LANDING AND TAXI TO GATE. DURING APU/BURNING RUBBER SMELL INSPECTION FOUND LT RECIRC-COCKPIT FAN HAD FAILED CAUSING SMOKING SMELL. (K) RAI LEFT RECIRCULATION FAN, OPS CHECK GOOD. AIRCRAFT RETURNED TO SERVICE. (M)