What happened
On 5 January 2014, a Singapore Airlines Airbus A380-800, registration 9V-SKE, diverted to Baku, Azerbaijan, following a period of cabin altitude instability. The flight, which originated from London, had previously experienced loud noises near the third left door (Door 3L) during its preceding leg from Singapore to London. Although maintenance personnel had inspected the door and noted a worn seal, no structural anomalies were found, and the defect was logged for future rectification.
During the flight from London to Singapore, the same loud noise was reported by cabin crew shortly after takeoff. While the flight crew initially monitored the aircraft's pressurization and found it stable at 6,000 feet, the situation changed approximately five hours into the flight. The crew received an electronic alert indicating a rising cabin altitude, which eventually escalated to a formal warning of excess cabin altitude.
As the cabin altitude approached 10,000 feet, the crew initiated an emergency descent and declared a MAYDAY. After an initial plan to divert to Ashgabat, Turkmenistan, was complicated by information that the airport was not suitable for an A380, the crew diverted to Baku. The aircraft landed safely with no injuries to any person.
The investigation
Investigators examined the physical condition of the aircraft and the sequence of events leading to the decompression. Laboratory examinations of the damaged door revealed that the skin at the top left corner of Door 3L had been torn and bent outward. The investigation also reviewed maintenance logs, flight recorder data, and the adequacy of the aerodrome's rescue and firefighting capabilities during the diversion.
Findings
- The failure of Door 3L was caused by a crack passing through several rivet holes in the door skin.
- This crack was likely the result of high-cycle fatigue caused by the fluttering of an older version of the door coverplate (Batch 1) previously installed on the aircraft.
- Evidence suggested the crack had been present since at least August 2012, as traces of sealant and paint were found within the crack surfaces.
- The investigation noted that the use of an aerodrome with a lower rescue and firefighting category than the aircraft's requirement could potentially compromise safety levels.
Safety action
Following the incident, the aircraft manufacturer issued a transmission to all A380 operators regarding noise reporting procedures. The operator implemented a fleet-wide inspection of passenger doors and updated cabin crew training regarding the manual activation of oxygen masks. Additionally, the operator has been working to implement a door structure reinforcement program as recommended by manufacturer service bulletins.