SA-227 AC Metro III
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Returned To Departure Airport; Flight Crew Landed As Precaution; General Maintenance Action
Procedure; Human Factors
Climbing out of [departure airport at] 14;000 feet. Notice a smell of smoke; started looking around feeling circuit board panels. Then smoke started to fill the cockpit just enough to see it. It did not smell like gas or exhaust more like paper burning. I was unable to hear Approach climbing out moments early on the number two radio and had to switch to number one. So immediately though it was smoke coming from the avionics so I turned the avionic master off. No change after a minute; more smoke in the cockpit; looking out the copilot's window is hazy. Turned avionic master back on; contacted Center that I would like to cancel IFR and return to departure airport. Once descending and direct [departure airport] troubleshot more; turning heat off and bleed valves. Contacted Dispatch; advised situation and coordinated where to park. 8;000 feet direct Runway 17. Smoke has now dissipated and cockpit clear; advised Tower no more smoke. Landed Runway 17. While unloading discovered 3 boxes; one Styrofoam two cardboard on the floor next to bleed heat vents. Scorching [observed] on the labels of the two cardboard and on the side of the styrofoam box. No other defects found.Keep styrofoam and labels from direct contact with bleed air heat vents and [do] not turn bleed air heat to max heat.
The pilot noticed smoke in the cockpit shortly after takeoff. All of the cargo was offloaded so that maintenance could inspect the aircraft. The loaders and pilot found a couple boxes placed too close to the bleed air duct vents that had signs of being overheated. Maintenance later released the aircraft back into service.Loaders need to ensure that they are not loading cargo near air bleed vents.
SA227 pilot and dispatcher reported the flight returned to departure airport after noticing smoke in the cockpit that was later traced to boxes placed near bleed heat vents.