What was found
NR 2 ENGINE START NORMAL INDICATIONS WHEN START LEVER PLACED TO IDLE. SHORTLY AFTER, TUG COMMANDED "ABORT" DUE TO SPARKS NEAR TAIL PIPE. PER QRC, PUT START LEVER - CUTOFF. N1 AND N2 BOTH WENT TO 0 WHILE START SWITCH STILL ON GND. GROUNDED - YES. REMOVED AND REPLACED ENGINE START VALVE, REF AMM 80-11-03. REMOVED AND REPLACED NR 2 ENGINE STARTER, REF AMM 80-11-01. REMOVED AND INSTALLED QAD ADAPTER 2, REF AMM 80-11-02. INSPECTED CHIP DETECTORS AND SCAVENGE SCREEN, NO MATERIAL FOUND, REF AMM 79-00-00. PERFORMED LEAK CHECK OF NR 2 ENGINE START VALVE, NO LEAK NOTED, REF AMM 71-00-00, AND THE AIR STARTER LEAK CHECK, REF AMM 71-00-00, NO LEAK NOTED.