Learjet 35
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Workload; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Weight And Balance; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft
During initial climb out (400 or 500 ft.) we heard a call from Medical saying that 'something's burning'. I looked behind and noticed the cabin was beginning to fill with a smokey hazy layer. The temperature in the airplane had increased and now the smoke was reaching the cockpit. I reset both bleed air valves in case we had a stuck valve; but this did not change anything. I told FO (First Officer) to turn off all fans in case that is the cause. I looked back again and I could visible see the smoke rising out of the rear right wall panel. We stopped the climb at 2;500 ft.; [advised ATC] and I made the decision to return back to ZZZ. I assumed control of the airplane and radios while FO completed checklist and set us up on the approach and calculated the weight of the airplane. He advised me that we were currently 500 lbs. overweight; I made the decision to still continue to the airport as I did not know the cause of the smoke and did not want to waste any time burning off extra fuel. We ultimately made a safe left base visual approach and landed 300 lbs. overweight. We were able to taxi into the ramp and shutdown and safely exited the airplane. We followed checklist and [Company] SOP.
Learjet-35 Captain reported a fumes event during climb resulting in a return to the departure airport.