Flight Crew Commercial; Flight Crew Instrument
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Human Factors
During preflight the Mechanic was in cockpit still doing his work. I visually verified that the right cowling was locked but did not physically verify. After Mechanic finished I continued my paperwork check and started the aircraft. When I was 200 ft. airborne; the cowling started to open partially. I requested to return to the runway and land without declaring an emergency. I was distracted which caused an interruption of flow during preflight. I called Dispatch; Director of Maintenance and Director of Operations to inform them of the situation. I should preflight thoroughly and avoid distractions. If interrupted; start over and verify with check list.
C208 Pilot reported the right cowling partially opened after takeoff.