What was found
(CAN) WHILE LOWERING THE FLAPS DURING ROUTINE MAINTENANCE, THE FLAP POWER DRIVE UNIT (PDU )WAS LABOURING. THE FLAP DRIVE SHAFTS WERE DISCONNECTED AT THE PDU, BUT THE PDU WAS STILL LABOURING. THE PDU WAS REPLACED, BUT THE CONDITION STILL PERSISTED. THE K670 CONTACTOR WAS REPLACED AND THE PDU OPERATED NORMALLY. THE SUSPECT K670 CONTACTOR WAS TAKEN APART AND DISCOVERED THAT THE CONTACTS WERE BADLY BURNED.