What was found
ON PREFLIGHT WITH APU RUNNING AND AC ON, SMELLED OILY ODOR AND SAW LIGHT SMOKE IN CABIN. WITH BLEED AIR OFF, SMOKE WENT AWAY WITH JUST A LITTLE OIL ODOR. REMOVED L/R APU PANELS, REMOVED INLET TEMP BULB, UNBOLTED INLET AND MOVED UPWARD TO ACCESS APU INLET. REMOVED TAIL TO RUDDER FAIRING/INTAKE. CW BORESCOPE OF APU INLET, PUT PIC ON FLASH DRIVE. APU INLET AND COMPRESSOR AREA INLET VERY OIL COVERED 9-22-12. RECORDED APU TIME: 3025.5, CYCLES: 4936. REMOVED APU FROM AIRCRAFT. RECEIVED PROVIDED APU. TRANSFERED COMPONENTS, OK TO INSTALL REPLACEMENT APU. INSTALLED APU IAW MM CH 49-10-00. OK TO INSTALL START/GEN RUN AND LEAK CHECK GOOD. OK TO CLOSE APU PANELS. CLOSED PANELS.