Incident Summary
The aircraft had been pushed back from the gate and both engines were started. The pneumatics system was shifted from the auxiliary power unit to the engines. Shortly thereafter, smoke was observed in both the cockpit and the passenger cabin. The flight crew donned their smoke masks, and the captain ordered an emergency evacuation of the aircraft.
Evacuation and Injuries
During the evacuation, two passengers sustained serious injuries, and an additional 32 passengers received minor injuries. The evacuation proceeded as the crew directed passengers to the exits.
Investigation Findings
An investigation into the incident determined that the source of the smoke was a hydraulic check valve failure. This failure allowed hydraulic fluid to enter the engine pneumatic duct, producing the smoke that filled the cockpit and cabin.
Door Malfunction
The investigation also noted that the 3R door evacuation slide did not deploy during the evacuation. Further inspection revealed that the door had not fully opened. However, when the door was manually pushed during the investigation, it opened fully, and the slide deployed and inflated as designed.