What was found
JFK - FLT 8703 - THE LEFT GEN FAILED, NO VOLTS OR FREQS. APU STARTED AND RAN NORMALLY FOR 30 MINUTES THEN APU GEN FAILED, NO VOLTS OR FREQS RETURNED TO JFK. THE LEFT GEN WAS DEFERRED PER MEL, AND THE APU GENERATOR CONTROL UNIT WAS REPLACED. IN FLIGHT, THE APU GENERATOR RAN NORMAL FOR AWHILE THEN FAILED. FLT AGAIN RETURNED TO JFK. REPLACED THE LEFT CSD MFG PN 696233B, AND THE APU GENERATOR. (M)