What was found
FLT#1258, PBI-BOS. 'DIRTY SOCK SMELL DETECTED AT FL 270, FL 230 SUSTAINED TO GROUND, DETECTED IN COCKPIT AND CABIN; TROUBLESHOT PER TSM 05-50-00-810-831-A, DECISION TABLE LED TO APU CONTAMINATION EVEN WITH ODOR HAPPENING IN FLIGHT. FOUND APU COOLING FAN LEAKING OIL SEVERELY. REMOVED AND REPLACED COOLING FAN IAW AMM 49-52-51. PERFORMED DECON OF BLEED & ECS (LEVEL B DECON). NO SMELL NOTED, A/C OKAY FOR SERVICE.'