Summary

On 22 December 2010, a Finnair Airbus A330-300 inbound to Helsinki and cruising in very cold air at an altitude of 11,600 metres lost cabin pressurisation in cruise flight and completed an emergency descent before continuing the originally intended flight at a lower level. The subsequent Investigation was carried out together with that into a similar occurrence to another Finnair A330 which had occurred 11 days earlier. It was found that in both incidents, both engine bleed air systems had failed to function normally because of a design fault which had allowed water within their pressure transducers to freeze.

Description

On 22 December 2010, a GE CF6-80E powered Airbus A330-300 being operated by Finnair on a passenger charter flight from Krabi, Thailand to Helsinki Finland was at a cruise altitude of 11,600 metres (38,100 feet) south of Moscow, Russia in night Visual Meteorological Conditions (VMC) when successive malfunction of both engine bleed air systems occurred. A consequential loss of cabin pressurisation followed and after the flight crew had donned their emergency oxygen masks, a descent to 6600 metres (17700 feet) was made with the APU used to operate the pressurisation system once within Aircraft Flight Manual (AFM) limits. It was subsequently possible to restart both engine bleed air systems and the flight was continued to the planned destination without further event. None of the 298 occupants were injured.