What was found
(CAN) AFTER TAKE OFF, CABIN BEGAN TO FILL WITH FUMES AND OIL VAPOR. CREW TURNED OFF ENGINE BLEED AIR AND RETURNED TO AIRPORT. MAINTENANCE FOUND NR 1 ENGINE BREATHER HOSE HAD BEEN KINKED AND PINCHED CAUSING THE ACCESSORY CASE TO PRESSURIZE AND FORCE OIL TO PASS THE ENGINE LABYRINTH AND GARLOCK SEALS AND ENTER THE COMPRESSOR. SOME OF THIS OIL ENTERED THE CABIN THROUGH THE AIRCRAFT BLEED AIR SYSTEM CREATING FUMES AND VISIBLE OIL VAPOR. ENGINE BREATHER HOSE WAS INSPECTED AND REPOSITIONED. SEVERAL SUCCESSFUL GROUND RUNS WERE CARRIED OUT AND AIRCRAFT WAS RETURNED TO SERVICE.