What was found
PHX - EMERGENCY LANDING - FLT 0587 - ON DECENT INTO PHX EN ROUTE FROM IND APPROX 30 MINUTES OUT, LOST POWER TO NR 2 TRANSFER BUS, SEVERAL INSTRUMENTS AFFECTED, DECLARED EMERGENCY, LANDED WITHOUT EVENT. MAINT FOUND THE NR 2 TRANSFER BUS CIRCUIT BREAKER POPPED. RESET CIRCUIT BREAKER AND EXAMINED THE NR 2 GENERATOR CONTROL UNIT (GCU) AND R4 RELAY CONNECTIONS IAW BMM'S 24-24-01, 24-51-41, AND 24-58-21, NO DEFECTS WERE NOTED. REMOVED AND REPLACED THE NO. 2 GCU IAW BMM 24-21-81, PG. 401. PERFORMED ENGINE RUN, NO FAULTS NOTED. VENDOR BENCH TEST OF GCU S/N WF080 CONFIRMED FAILURE OF UNIT FOR FAILING FREQUENCY AND DROPOUT TEST. REPLACED RELAY , RELAY , TRANSISTOR SEMICONDZENER, AND SPACER. UNIT REPAIRED AND TEST IAW.