What was found
THE FLIGHT CREW REPORTED THAT SHORTLY AFTER TAKEOFF, LIGHT SMOKE ENTERED THE COCKPIT. AFTER SHUTTING DOWN THE AUXILIARY POWER UNIT (APU) THE SMOKE DISSIPATED. THE FLIGHT CREW RETURNED BACK TO THE AIRPORT AND COMPLETED A PRECAUTIONARY LANDING WITH INCIDENT. A MAINTENANCE VENDOR DETERMINED BY BORE SCOPING THAT AN INTERNAL OIL SEAL TO THE APU FAILED CAUSING THE SMOKE IN THE COCKPIT/CABIN. THE CAUSE TO THE FAILED OIL SEAL WILL BE DETERMINED ONCE THE APU HAS BEEN DISASSEMBLED AND EVALUATED APU MODEL RE100(XL) S/N P575.