Date: 201909
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Dawn
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Aircraft component: Air Conditioning and Pressurization Pack
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Situational Awareness
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Attendant; Person Flight Crew
When detected: Taxi
Result: Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Gate
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: After pushback with engines running; Flight Attendant called flight deck reporting light smoke and fumes in cabin. Myself and First Officer noticed a light smell of fumes in the flight deck without the presence of smoke. While I was talking to the flight attendants over the intercom First Officer noticed the L PACK AUTOFAIL caution msg came on. I got off the phone with the flight attendants and called for Emergency Checklist smoke and fume removal. After looking at the checklist; I determined it was not necessary and called for QRH L PACK AUTOFAIL checklist. QRH directed us to select Manual Mode and manually control Temp with toggle switch. The First Officer and I try to cool down the output temp by holding down the toggle switch for several seconds without any success. The output temp readout was at 99 degrees Celsius. After pressing Manual mode; L PACK AUTOFAIL msg went away and then followed by L PACK TEMP caution msg came on. By this time; I have made a few announcements to the passengers to keep them informed of the situation and had by this point 2 conversations with both flight attendants of the situation. The second conversation with the flight attendants; the Flight Attendant called over the Emergency intercom to tell us that the passenger in XXA had a hot seat. I asked them to keep me posted and told them that the cause of the hot seat and hot temp in the back of the plane was due to a broken L pack. After not able to cool the output of the L Pack; I called for QRH L PACK TEMP checklist and the QRH directed us the turn off the Left pack. I asked the First Officer to call OPS and Ground to coordinate a gate return. Ground acknowledged request; but no answer on OPS frequency. First Officer called Ops on the phone and was able to get a hold of them and we told them we needed to return to the gate to deplane passengers. Ops acknowledge request; but no action was taken for a few minutes. While First Officer was coordinating a gate return; I was talking to flight attendants about cabin status. The flight attendants reported that cabin condition was improving. Fumes and smoke were dissipating and temperature was starting to cool down. We waited a few more minutes to hear back from Ops to get a ramp crew out to park us with no results. I called them over the phone myself to expedite our return to the gate. Ops told us that they were working on it. A few seconds went by and we got a call from Ops over frequency asking to push another aircraft before they would come over and park us back at gate. We declined their request and ask to be parked first. They asked if this was an priority handling and to expedite our return to the gate I [advised]. We returned to the gate and a police officer boarded the plane to assist and assess the situation. We had to deplane the passengers using the passenger door due to the ground crew parked us short and the jet bridge couldn't reach the plane.The cause of the light smoke and fumes in the cabin was due to the Left pack malfunctioned and broken causing dust and water vapor to enter the cabin. The hot aft cabin also due to hot temperature output by the Left pack. We expedited our return to the gate; because we would have sat there for a while waiting for ramp personnel to park us.


Second narrative: After completing pushback with the engines running; the forward Flight Attendant called the flight to inform us that there was light smoke and fumes in the cabin. Both the Captain and I did smell light fumes but did not see any smoke in the flight deck. While talking to the forward Flight Attendant; I saw a L PACK AUTOFAIL msg displayed. The Captain called for the Emergency Checklist for smoke but determined it wasn't necessary and continued to run the QRH for L PACK AUTOFAIL. The QRH directed us to switch to manual mode which caused the L PACK AUTOFAIL message to disappear but was followed by a L PACK TEMP message as the output temperature displayed 99 [degrees] Celsius. The QRH then directed us to turn off the L PACK. The Flight Attendant called using the EMERGENCY call to inform us that a passenger in XXA reported their seat and wall being hot. While the Captain was talking with the flight attendants; I called Ground and Ops for a potential gate return. I had difficulty reaching Ops on the radio and called the number listed on the company page. Meanwhile; the Captain got an update from the Flight Attendant that the smoke and fumes from the cabin started to improve and dissipate. I called Ops again on the phone as no one was picking anything up over the radio and informed that we needed a ground crew for an immediate gate return due to smoke and fumes in the cabin. After a few minutes without the ground crew in sight; the Captain called Ops for an immediate gate return. Ops started to contact us over the radio and requested if they could push a different crew before they could assist us in the gate return. I denied their request; as directed by the Captain; and they respond if we were [advising]. The Captain and I agreed to [advise] in order for the ground crew to give us priority handling. The ground crew then marshaled us to the gate but short of the reach of the jet bridge. We deplaned through the passenger door and the Captain assisted with the deplaning while I contacted Dispatch and Maintenance Control.Smoke and fumes entered the cabin due to a malfunctioning L PACK. We received a L PACK AUTOFAIL message in which the QRH directed us to switch to manual mode; which caused a L PACK TEMP message to appear. A temperature output of 99 [degrees] Celsius displayed and the QRH directed us to turn off the PACK. After turning off the PACK; smoke and fumes started to dissipate. Difficulty with getting in touch with the ground crew added additional challenge as they were not responding to our requests to get priority handling.I should have been more assertive when I initially called Ops through the phone as it took several phone calls and [advising] to grab their attention and assist us in the situation.


Synopsis: CRJ-900 flight crew reported Flight Attendant notification of light smoke and fumes in the cabin followed shortly by experiencing fumes on the flight deck after pushback.