History of Flight
The Air Canada flight ACA 433, operated with an Airbus A320-211 (registration C-FTJO, serial number 183), departed Montréal/Pierre Elliot Trudeau International Airport, Quebec, for Toronto/Lester B. Pearson International Airport, Ontario. On board were 98 passengers and 6 crew members. During pre-flight preparations, the auxiliary power unit (APU) was started, and a brief odor was noticed in the cabin, which dissipated after adjustments. After takeoff, the odor returned but again dissipated.
Hydraulic System Failure
As the aircraft approached the top of climb, the electronic centralized aircraft monitor (ECAM) alerted the crew to a low reservoir level in the green hydraulic system. The crew performed ECAM procedures, which included deactivating the hydraulic power transfer unit (PTU) and the green system engine-driven pump. Consequently, systems such as nose wheel steering, normal brakes, normal gear extension, and the number 1 thrust reverser became inoperative. The crew decided to continue to Toronto due to better weather. The landing gear was extended using the emergency system, and the aircraft made an uneventful landing on runway 05 at 0844 Eastern Daylight Time. The aircraft came to a stop and waited for a tow.
Evacuation
While stopped on the runway, the tow operator requested that the landing gear doors be closed. After consulting with maintenance, the crew re-energized the green hydraulic system by activating the electric hydraulic pump and PTU. Almost immediately, smoke began entering the cabin and cockpit. The pump was turned off, but smoke continued to enter through air vents. The left side passenger doors (L1 and L2) were opened in an attempt to ventilate, but the smoke persisted. Concerned passengers moved toward the open doors, and the captain ordered an evacuation after the service director reported the situation. The cabin crew closed and re-armed the doors, then all four doors were opened, and emergency slides deployed. Passengers also opened over-wing emergency exits. The evacuation was completed in approximately two minutes. Light rain made the slides damp, and two passengers who carried baggage reported minor injuries, including scraped knuckles and sore backs. Two crew members also reported back injuries during their exit.
Post-Inspection Findings
Maintenance the night before had added 6 liters of hydraulic fluid to the green system and noted a leak for monitoring. A post-flight inspection revealed that a faulty yaw damper had leaked fluid, which flowed into the APU intake. The APU then heated and sent the fluid through the bleed air system into the cabin. The yaw damper leak was caused by degradation of the piston rod seals due to a rough surface finish on the piston rod. Although the manufacturer had issued non-mandatory service bulletins for modifications and a service information letter for inspections, Air Canada had not performed the modifications, considering the risk low. The cockpit voice recorder did not capture the event because it stopped five minutes after engine shutdown, which occurred 16 minutes before the evacuation.
Carry-On Baggage
Several passengers evacuated with carry-on baggage despite instructions to leave belongings behind. The airline's safety briefings did not include a specific directive to leave baggage, though Transportation Safety Board recommendation A07-07 had called for such instruction. Air Canada was in the process of implementing this change.