An Air Canada Boeing 787-900, registration C-FGHZ performing flight AC-882 from Toronto,ON (Canada) to Copenhagen (Denmark) with 302 people on board, was climbing through FL250 about 40nm east of Toronto when the crew noticed the cabin altitude was climbing through 9800 feet, declared emergency and requested an immediate descent to 10,000 feet. The aircraft subsequently dumped fuel and returned to Toronto for a safe landing on runway 23 about one hour after declaring emergency. The crew requested emergency services to follow the aircraft to the gate.
The Canadian TSB reported that maintenance discovered the Electronic and Equipment (E/E) bay cooling exhaust valve was almost entirely (94%) open. The E/E cooling exhaust fan assembly was replaced and an operational check performed.
The Aviation Herald
Air Canada Boeing 787-9 has cabin pressurization problems, returns to Toronto Pearson
