What was found
DURING DESCENT AT APPROX 13,000 FEET, ATTEMPTED TO EXTEND THE FLAPS TO 20 THE SLAT/FLAP MAINT MESSAGE CAME ON AND THEY STOPPED AT 18 DEGREES. RECYCLED THE FLAPS AND THE MESSAGE CAME ON AGAIN AND FLAPS STOPPED AT 6 DEGREES. RECYCLED FLAPS AGAIN, THIS TIME THE MESSAGE CAME ON AND THE FLAPS WOULD NOT MOVE FROM THE 0 POSITION. LANDED WITH KRUEGERS AND SLATS EXTENDED, FLAPS AT 0. FSECU HAD FLAP SYSTEM JAM LIGHT ILLUMINATED. REMOVED FLAP PDU AND INSTALLED REPAIRED FLAP PDU IAW CMP 275210. COMPLIED WITH CMP 275101 FLAP/SLAT CONTROL AND DRIVE SYS FUNCTIONAL TESTED WITH NO DEFECTS NOTED.