What was found
FLIGHT ATTENDANT'S COMPLAINED OF ACRID DIRTY SOCK CABIN ODOR AFTER APU START & APU BLEED ON WHILE ACFT WAS PARKED AT GATE. ACCOMPLISHED JOB CARD 26L00021001 & DETERMINED APU TO BE THE SOURCE OF THE ODOR. FOUND THE APU NR 4 CAVITY VENT TUBES LEAKING. R & R APU NR 4 CAVITY TUBE PACKING IAW MM 49-91-53. OPERATIONS CHECKED GOOD. FOUND THE APU INTAKE DIRTY, CLEANED APU INTAKE IAW MM 49-16-00-100-001, OPERATIONS CHECKED GOOD.