What was found
WITH APU ON FOR 15 MIN, CAB IN FILLED WITH SMOKE. OIL SMELL TO IT. BLEED AIR ON, TEMPS NORMAL ON APU. CABIN SEEMED TO NOT BE COOLING EFFECTIVELY. - FOUND APU STARTER/GENERATOR GARLOCK SEAL LEAKING OIL INTO ENCLOSURE - REPLACED SEAL IAW HONEYWELL RE100 (XL) MM 49-10-00. ALSO FOUND AREA AROUND FILLER PORT APPEARS TO HAVE OIL SPILLED INTO APU AIR INLET. BOROSCOPE APU NO INTERNAL LEAKS NOTED. REPLACED COALSCER SOCK AND CLEANED ECU & DUCTING TO REMOVE OIL IAW ALIED SIGNAL MM IV SCREW 4-7 OPS/LEAK CHECKS GOOD.