Summary
On 2 July 2012, an AVRO 146-RJ100 aircraft, registration HB-IXW, was involved in a serious incident while flying 24 nautical miles southeast of the Rolampont (RLP) VOR beacon in France. At flight level 244 (7437 m), the cabin pressure ventilation system failed completely, prompting the crew to execute an emergency descent to a safe altitude.
Sequence of Events
The flight was a scheduled service, and prior to departure, air conditioning pack 1 had been deactivated. During cruise, a defect occurred in the right bleed air distribution system. This defect led to a total loss of cabin pressure ventilation, triggering cockpit warnings. The crew donned oxygen masks and initiated an emergency descent in accordance with procedures. The descent was coordinated with air traffic control, and the aircraft landed safely at its destination.
Technical Findings
Investigation by the Swiss Accident Investigation Board (SAIB) identified that the right bleed air distribution system suffered a defect that caused the complete failure of the cabin pressure ventilation system. The system is designed to supply conditioned air for pressurization and temperature control. The deactivation of air conditioning pack 1 before the flight reduced system redundancy, which was a contributing factor.
Contributing Factors
The serious incident was directly attributable to the defect in the right bleed air distribution system. Additionally, the fact that air conditioning pack 1 had been deactivated prior to the flight contributed to the severity of the event by eliminating a backup source of pressurization.
Investigation Conclusion
The SAIB determined that the serious incident was caused by a defect in the right bleed air distribution system leading to a complete failure of the cabin pressure ventilation system, with the prior deactivation of air conditioning pack 1 as a contributing factor. No other causal factors were identified.