Narrative:

We arrived at the airport and performed our duties for first flight of the day. The night had been very cold; but the aircraft did have external power and an external air cart attached. All preflight checks were normal and the APU was started just prior to passenger boarding for heating. I did review the logbook and noticed an issue with the right pack just the day before. After the APU had run for at least 2 minutes; I started the left pack and a few minutes later the right pack. After the right pack had been on a few minutes; we received a 'right pack high temperature' caution message. We referred to flight manual and shut the pack off. Thinking the pack may have been working too hard in the cold weather; we selected the temperature on the right side to a colder setting and let the pack cool a few minutes. By now passengers were boarded and the weight and balance was being completed. The checklist guided us to try the pack again. The main passenger door was closed a few minutes prior to departure. About this time I re-selected the right pack on and had the ecs page selected. I noticed on the synoptic page the right duct temperature out of the right pack was rising quickly. Within moments; we had a 'right pack high temperature' caution. As we were reaching for the manual; we had a 'smoke toilet' caution and the lavatory smoke detector started sounding. The cockpit door was still open since we had not started either engine and the flight attendant told us there was smoke in the cabin. She made an announcement for the passengers to stay seated and I asked her to open the main door. We looked for a 'smoke toilet' caution checklist in the manual but could not find one. With the main door open and the right pack off; the smoke began to dissipate quickly and the passengers were deplaned through the main door and jetway. EICAS 'right pack high temperature' caution quickly followed by 'smoke toilet' caution and lavatory smoke alarm sounding. There was a haze in the cabin and strong odor. Flight attendant advised us of the haze and odor since the cockpit door was open. Passengers were told to stay seated. Checklists were covered. The main door was opened to prepare in case of evacuation and for ventilation. Passengers were taken off the plane in an orderly fashion. The right pack went over-temperature and caused a smoke and odor in the cabin. It was a maintenance issue; but there should be a checklist for 'smoke toilet' caution and not just 'smoke toilet' warnings. Clarification should be made as to whether the same checklist should be used in both cases. In this case; the checklist for either really didn't apply since the smoke was from the pack; but if you were to get just the 'smoke toilet caution and no other EICAS items; there should be a checklist to refer to. Since we were at the gate with only the APU running most of the checklist items did not apply.

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Original NASA ASRS Text

Title: Cold soaked CRJ-900 utilizing external power and an air cart received 'R PACK HI TEMP' and 'SMOKE TOILET' caution messages while parked at the gate. Smoke was in the cabin; but there was no checklist for the 'caution' message; only a 'warning.'

Narrative: We arrived at the airport and performed our duties for first flight of the day. The night had been very cold; but the aircraft did have external power and an external air cart attached. All preflight checks were normal and the APU was started just prior to passenger boarding for heating. I did review the logbook and noticed an issue with the right pack just the day before. After the APU had run for at least 2 minutes; I started the left pack and a few minutes later the right pack. After the right pack had been on a few minutes; we received a 'Right Pack High Temperature' caution message. We referred to flight manual and shut the pack off. Thinking the pack may have been working too hard in the cold weather; we selected the temperature on the right side to a colder setting and let the pack cool a few minutes. By now passengers were boarded and the weight and balance was being completed. The checklist guided us to try the pack again. The main passenger door was closed a few minutes prior to departure. About this time I re-selected the right pack on and had the ECS page selected. I noticed on the synoptic page the right duct temperature out of the right pack was rising quickly. Within moments; we had a 'Right Pack High Temperature' caution. As we were reaching for the manual; we had a 'Smoke Toilet' caution and the lavatory smoke detector started sounding. The cockpit door was still open since we had not started either engine and the Flight Attendant told us there was smoke in the cabin. She made an announcement for the passengers to stay seated and I asked her to open the main door. We looked for a 'Smoke Toilet' caution checklist in the manual but could not find one. With the main door open and the right pack off; the smoke began to dissipate quickly and the passengers were deplaned through the main door and jetway. EICAS 'Right Pack High Temperature' caution quickly followed by 'Smoke Toilet' caution and lavatory smoke alarm sounding. There was a haze in the cabin and strong odor. Flight Attendant advised us of the haze and odor since the cockpit door was open. Passengers were told to stay seated. Checklists were covered. The main door was opened to prepare in case of evacuation and for ventilation. Passengers were taken off the plane in an orderly fashion. The right pack went over-temperature and caused a smoke and odor in the cabin. It was a maintenance issue; but there should be a checklist for 'Smoke Toilet' caution and not just 'Smoke Toilet' warnings. Clarification should be made as to whether the same checklist should be used in both cases. In this case; the checklist for either really didn't apply since the smoke was from the pack; but if you were to get just the 'Smoke Toilet caution and no other EICAS items; there should be a checklist to refer to. Since we were at the gate with only the APU running most of the checklist items did not apply.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.