Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Distraction; Physiological - Other; Situational Awareness; Time Pressure; Troubleshooting; Workload
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport
Aircraft
On takeoff and climbing through 3;500 ft. we noted smoke entering the cockpit.  This was second time it happened on the same aircraft; as we had landed from a priority landing from same problem.  We donned oxygen masks; advised ATC; ran appropriate checklists and landed without incident.After the fact our Maintenance personnel bore scoped the engine and found a broken engine oil seal which leaked into the Environmental Control System and fed oxidized jet fuel into the cabin through the PAC turbine.  Engine was swapped after [a] ferry flight.Should have bore scoped engine after first priority landing.
Air Carrier Captain reported smoke in the cockpit just after takeoff. The Captain ran the QRH and made an immediate landing. Maintenance found a broken oil seal in the engine.