Date: 201811
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Dusk
Aircraft: Learjet 60
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Tower ZZZ
Reporter organization: Corporate
Reporter function: Captain; Pilot Flying
Human factors: Time Pressure
Second reporter function: Captain; Pilot Not Flying
Anomaly: Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Crew
When detected: Taxi
Result: Air Traffic Control Provided Assistance; Flight Crew Took Evasive Action; General Evacuated
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: After start up; all system checks were normal. We began our taxi to Runway XXR for takeoff and were holding short of Runway XY when Tower told us it would be at least a 15 minute delay to take off unless we could takeoff Runway XZ. We accepted Runway XZ and taxied onto Runway XY then made an immediate right onto Taxiway Foxtrot and then a left onto Taxiway A. We were cleared to cross both Runway XXR/L. At about 200 feet from the hold short line of Runway XZ; we both looked at each other and asked if we smelled a musky smell in the airplane. At that time we looked back in the cabin and realized it was filling up with smoke. I came to a stop at the hold short line of Runway XZ and my co-pilot called for the truck to start rolling and I [advised ATC] after asking if we were declaring an emergency. I immediately shut off the left engine and my co-pilot opened the door and ran to the back of the airplane to look in the back to make sure there was no smoke coming out anywhere. He then came back into the airplane and said he didn't spot anything and began evacuating the passengers from the airplane as I continued to shut the airplane down. I notified Tower I was going off com and exited the plane. The fire department showed up and could not find anything wrong and left. We then had the airplane towed to the FBO where it sits for maintenance to look at it.


Second narrative: Normal startup and taxi. APU was turned off on ramp before taxi. Taxied to [Runway] XXR and we were holding short of Runway XY when Tower advised us of lengthy delay; but could get us out sooner on [Runway] XZ; so we accepted taxi to [Runway] XZ. As we approached the hold short line of [Runway] XZ; approximately 8-10 minutes from start of taxi; we observed a musty smell; along with a slight increase in temperature and then moderate smoke filling the entire cabin. We did not observe any abnormal indications other than the smoke. I; (Non-Flying Pilot); turned off both bleed airs; and asked Tower if they could see any smoke from our aircraft. They said no. I then told them we had smoke in the cabin and could they please send out the fire trucks. I then asked Pilot Flying to shut down the left engine so I could open the cabin door; and go back and inspect the tail cone and rear baggage compartments for any signs of smoke or fire. By this time; with the bleed airs off and the cabin door open; the smoke appeared to be dissipating. I went back to check the rear compartments and everything appeared normal. We evacuated the passengers and performed the Evacuation Checklist. We then made calls to Ops; Maintenance and the Chief Pilot while we waited for the fire trucks to arrive. (It took a while since they were the off field City Fire Department. The on field fire crew; which consisted of the FBO line crew; arrived much earlier; within a few minutes.) The passengers were loaded in a van and returned to the FBO; and we had the aircraft towed back by the tug after the Firemen inspected and cleared the plane. We wrote up a maintenance discrepancy and turned the aircraft over to Maintenance.


Synopsis: Lear 60 flight crew reported evacuating the aircraft on the taxiway due to smoke in the cabin.