What was found
DURING CLIMB, ENG NR 1 IN FLT SHUTDOWN. ACFT DIVERTED TO IAD. MX FOUND METAL DEBRIS ON CHIP DETECTOR. MX R & R ENGINE. OPS CHECKS PERFORMED SUCCESSFULLY. ACFT APPROVED TO RETURN TO FLT. REMOVED ENG FOR INVEST & REPAIR. DFDR DATA REVIEWED & INDICATED N2 STEADY AT 97%, AT 1 SECOND INTERVALS - N2 WENT 94%, 96%, 91%, 78%, 12%, 8%, 0%. NO ASSOCIATED INCREASE IN FUEL FLOW OR ITT. MOMENTARY SPIKE IN N2 GOING FROM 92-96-91 INDICATED AFTER AGB INPUT GEAR FAILED MOMENTUM OF BOTH AGB & HPC ALLOWED INPUT GEAR TO RE-ENGAGE STARTER GEAR SHAFT & ACCELERATE AGB MOMENTARILY FOLLOWED BY PERMANENT DISENGAGEMENT. ENGINE FAILURE CAUSED BY AGB INPUT BEVEL GEAR FRACTURED IN FATIGUE FROM TOOTH ROOT RADIUS ON BOTTOM SIDE OF GEAR RESU