Summary
On November 17, 2022, at 17:48 UTC, an Airbus A319-111 aircraft, registration G-EZBV, operated by easyJet UK Limited, experienced a serious incident during a ferry flight from Sofia Airport (LBSF), Bulgaria, to London Gatwick Airport (EGKK), United Kingdom. The flight crew consisted of two persons. Approximately 10 minutes after departure, while climbing through Flight Level 290, a Cabin Altitude Warning appeared on the Electronic Centralized Aircraft Monitor (ECAM). The crew leveled off around FL300, donned oxygen masks, declared a MAYDAY, and initiated an emergency descent back to Sofia. The cabin altitude rose to about 9,000 feet, indicating low cabin pressure. During the descent, cabin pressure slowly recovered and reached normal values at 10,500 feet. The aircraft landed safely on runway 27. There were no consequences for the flight crew.
Event Details
The flight, designated EZY9002, was a ferry flight conducted after base maintenance at Sofia Airport. The aircraft's pressurization system failed during climb. The crew responded by leveling off, using oxygen masks, and squawking 7700. The emergency descent was performed as per procedures. The incident was classified as a serious incident by the Air, Maritime and Railway Accident Investigation National Board (AMRAINB) of Bulgaria. The investigation was supported by Airbus and Lufthansa Technik Sofia.
Investigation
The investigation examined maintenance procedures performed by Lufthansa Technik Sofia during the base maintenance checks. The focus was on the installation of the aft cargo door pressure seal. The analysis revealed that the technological process for installing the seal was disrupted, leading to an improper seal that allowed air leakage, resulting in the loss of cabin pressurization.
Probable Cause
The root cause of the serious incident was determined to be: disruption of the technological process of the installation of the aft cargo door pressure seal during the base maintenance activities by the maintenance crew of Lufthansa Technik Sofia.