PC-12
Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Workload; Time Pressure; Distraction; Confusion
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
On initial climb we started to smell burning oil that got progressively stronger. No visible smoke; smell seemed to be coming from the air conditioning vents. We continued climb; brought flaps up; and switched to departure while attempting to determine the source/cause. We decided to return; rather than proceed over water for extended period; however departure frequency was too busy to notify. We switched back to tower and notified them and we began turning back. Tower advised Departure and asked if we were declaring an emergency. We did not declare and tower cleared us to land. We turned off the air conditioning to rule it out; ran the approach check and set up a base leg. Odor remained but was not as strong after power reduction for the turn back. Crew did not don O2 mask; no visible smoke and fumes were not incapacitating. Did not pull air conditioning shutoff as we were busy with configuring for landing. Ran before landing and prior to landing checks and landed without incident.  Still no visible smoke. Taxied to FBO; shut down and upon opening the door; FO noticed same odor from left side forward; cowling area. Two Ramp Agents also noticed same odor/smell. Opened forward left cowling no visible signs of oil or abnormal conditions. Talked to maintenance; they pointed us to a few different areas to inspect (both engine cowlings; Nose gear area; air conditioning and generator air intake; oil cooler; separator; air intake; prop area; both mains; gear motor area; aft equipment bay) however nothing abnormal detected. Approximately 15 minutes later while in the area of the air stair; similar smell was detected by both crew members.
PC-12 Captain reported a burning oil odor with no visible smoke after takeoff. Unable to determine the source; the crew returned to land.