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ASN Wikibase Occurrence # 147264
Last updated: 26 April 2019
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Date:22-DEC-2010
Time:
Type:Silhouette image of generic A333 model; specific model in this crash may look slightly different
Airbus A330-302X
Owner/operator:Finnair
Registration: OH-LTS
C/n / msn: 1078
Fatalities:Fatalities: 0 / Occupants: 301
Other fatalities:0
Aircraft damage: None
Location:South of Moscow -   Russia
Phase: En route
Nature:International Non Scheduled Passenger
Departure airport:Krabi
Destination airport:Helsinki-Vantaa Airport (HEL/EFHK)
Narrative:
The aircraft, registration OH-LTS, was on a scheduled chartered flight from Krabi, Thailand to Helsinki-Vantaa airport. There were 286 passengers and 15 crew members onboard.
The aircraft experienced a loss of pressurisation due to dual engine bleed air system failures. The flight crew donned their emergency oxygen masks because of the decrease of cabin pressure.
The flight crew initiated a rapid descent from cruise level about two minutes after the loss of pressurisation. Excessive cabin altitude warning came on during the descent after which the flight crew continued by an emergency descent. OH-LTS continued to Helsinki-Vantaa airport, its planned destination.

This serious incident was caused by malfunctioning of the engines’ bleed regulated pressure transducers' (Pr). The malfunctioning was caused by freezing of water that had accumulated in the bleed regulated pressure transducers' pressure cell rooms, extremely confined by design. This being the case, the transducers provided faulty pressure information to bleed monitoring computers. Due to the erroneous information the computers closed both engines’ bleed air systems which resulted loss of pressurisation in cabin, i.e. an increase in cabin air pressure altitude. The extremely cold air mass enroute during a long time period contributed to the fact that the water froze in the pressure cell rooms. Furthermore, the relatively rapidly increasing ambient temperatures enroute may have contributed to the engine’s bleed air system faults.

Sources:

http://www.turvallisuustutkinta.fi/en/Etusivu/Ajankohtaista/1342536842578


Images:

Photo of OH-LTS courtesy AirHistory.net


Helsinki - Vantaa (EFHK / HEL)
30 April 2012; (c) Juhani Sipilä

Revision history:

Date/timeContributorUpdates
31-Jul-2012 13:38 harro Added

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