What was found
ON TAKEOFF FROM KMIA, UNABLE TO OBTAIN NECESSARY N1 OF 113.6 PERCENT FOR NR 2 ENG. AT N1 OF 109.0 PERCENT, RED WARNING CAME ON AND N1 MAINTAINED INDICATION AT 109.0 PERCENT. ON CLIMBOUT FROM KMIA, BOTH CHANNEL A & B NACELLE TEMPERATURE INDICATIONS WERE 5.0. REDUCED THRUST LEVER TO IDLE AND BOTH NACELLE TEMPS REDUCED TO 2.25 (A) AND 2.75 (B). ACFT RETURNED TO KMIA. NO FUEL WAS DUMPED. INSPECTION FOUND BLEED AIR PRECOOLER LEAKING WITH CRACKED FLANGE. ENG CHANGE REQUIRED. ALL AD`S ARE CURRENT FOR THIS ENG. (S)