What was found
DURING START OF APU, APU HANGS AT 9 PERCENT. STARTED ON FOURTH ATTEMPT WHICH RESULTED IN FIRE IN THE TAILPIPE, CAUSING DELAMINATION TO THE LOWER SIDE OF RIGHT ENGINE PYLON. REMOVED AND REPLACED APU IAW MM 49-10-00 DUE TO HIGH EGT & METAL ON CHIP DETECTOR. APU PN/ ON 3800488-3, S/N OFF P-676. ALSO REMOVED AND REPLACED APU ECU S/N OFF 44-F001. (THE CAUSE OF THE HUNG STARTS). OPS CHECK GOOD. PYLON REPAIRED IAW REO 601R-54-62-037.