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ASN Wikibase Occurrence # 163044
Last updated: 28 May 2017
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Date:06-JAN-2014
Time:01:03 LT
Type:Silhouette image of generic A388 model; specific model in this crash may look slightly different
Airbus A380-841
Owner/operator:Singapore Airlines
Registration: 9V-SKE
C/n / msn: 010
Fatalities:Fatalities: 0 / Occupants: 494
Other fatalities:0
Airplane damage: Minor
Category:Serious incident
Location:Baku -   Azerbaijan
Phase: En route
Nature:International Scheduled Passenger
Departure airport:London-Heathrow Airport (LHR)
Destination airport:Singapore-Changi Airport (SIN)
Narrative:
Singapore Airlines flight SQ317 from London to Singapore diverted to Baku, Azerbaijan due to a loss of cabin pressure.
On 4 January 2014, the day before the flight diversion incident, the aircraft operated a scheduled flight from Singapore to London. After take-off from Singapore, a cabin crew member noticed a loud noise coming from the third left door on the main deck (Door 3L). A flight crew member subsequently went to the cabin to check on the door and did not notice anything unusual, other than the loud noise.
Maintenance personnel had earlier visually inspected the door on 23 December 2013 because of a reported noise. No anomaly was found except for a slightly worn seal on the door's upper edge. An entry was made in the Aircraft Deferred Defect (ADD) log for this issue to be monitored. The ADD system allowed this defect to be rectified within 120 days.
After the aircraft arrived in London, the defect was reported to the maintenance personnel who then visually inspected the door. The areas inspected included door seal, seal guides, rollers, stops, coverplate (CP) and the condition of the exterior door skin. No anomaly was found, other than the slightly-worn seal noted previously. The defect remained on the ADD log.
On the aircraft's return flight to Singapore on 5 January 2014, the noise was heard again at Door 3L after take-off. The cabin crew member seated at Door 3L felt around the door but did not detect any air leak or vibration on the door.
After the take-off and once the seatbelt sign was switched off, the cabin crew member immediately informed her cabin zone leader who in turn informed the In-flight Supervisor (IFS). The IFS went to check on the door and detected no air leak or vibration on the door. He informed the flight crew when the aircraft reached the cruise altitude of 37,000 feet.
The cabin pressurisation was normal with the cabin altitude at 6,000 feet. A flight crew member subsequently inspected the door and did not notice anything unusual other than the noise. On return to the flight deck, the pilot transmitted an Aircraft Communications Addressing and Reporting System (ACARS) message to Singapore informing of the noise at Door 3L and requested that the problem be fixed before the next flight.
The extent of the noise was such that passengers and cabin crew members in the area around Door 3L could not clearly hear the announcements over the Public Address (PA) system. The flight crew was aware of the PA situation, but decided to proceed with the flight and monitored the aircraft's pressurisation system, having considered that the issue of a worn seal had already been captured in the ADD, that the pressurisation of the aircraft was normal, that the aircraft had operated normally from Singapore to London, that the noise condition was known and that maintenance personnel had checked the door and certified the aircraft fit for flight.
About five hours into the flight, a cabin altitude advisory appeared on the Electronic Centralised Aircraft Monitoring (ECAM) system which alerted the flight crew to the increasing cabin altitude of the aircraft. This advisory subsequently disappeared. The flight crew by this time was closely monitoring the pressurisation of the aircraft. About 30 minutes later, the flight crew noticed that the cabin altitude started to climb slowly. This resulted eventually in an ECAM warning of excess cabin altitude.
The flight crew executed an emergency descent as the cabin altitude was approaching 10,000 feet. The flight crew declared MAYDAY to Kabul Air Traffic Control (ATC) during the descent but did not get a response. Another aircraft which was flying in the vicinity heard their MAYDAY call and relayed the message to Kabul ATC.
The flight crew then made a decision to back-track and divert to Ashgabat in Turkmenistan, which was the nearest Decompression Alternate (DA) among those identified in the list of DAs in the operator's A380 Supplementary Procedures. The flight crew informed Kabul ATC of their decision to divert to Ashgabat.
The flight crew carried out actions according to the emergency descent checklist. Although not required by the checklist, but as a precaution, the flight crew deployed the passenger oxygen masks.
On the way to Ashgabat, the flight crew was informed by the Turkmenabat Area Air Traffic Control (TAATC) that Ashgabat is not suitable for A380 aircraft. After consulting the operator's headquarter via satellite communication, the flight crew decided to divert to Baku in Azerbaijan which was the next nearest airport. The aircraft landed in Baku without further incident.

CONCLUSIONS:
1. The Door 3L failure was traced to a crack passing through a number of rivet holes on the door skin. The crack was probably caused by high cycle fatigue under varying amplitude loading due to the fluttering of the Batch 1 CP that was initially installed on the aircraft. Once the crack was initiated, the stiffer Batch 3 CP could not prevent further propagation of the crack.
2. There were traces of sealant and paint in the crack surfaces as well as on the countersunk surfaces of two rivet holes, meaning that the crack was present when CP was replaced in August 2012.
3. As regards the PSUs in the bunks in the CCRC, some cabin crew members did not seem to be aware that a conscious effort is needed to pull on the mask, when lying down, in order to release the lanyard pin to allow oxygen to flow to the mask.
4. The amount of water required to be make available at an aerodrome of Category X can be significantly different from that required of a Category X-1 aerodrome. The smaller amount of water available at the Category X-1 aerodrome could compromise the desired RFFS protection level. ICAO guidance material does not seem to offer a methodology for airline operators to evaluate the extent of the compromise in fire protection level when an aerodrome of a lower category than the aeroplane category is used.

Sources:

http://news.asiaone.com/news/relax/sq-flight-317-london-makes-emergency-landing-azerbaijan

Accident investigation:
cover
investigating agency: Transport Safety Investigation Bureau - Singapore
status: Final
number: AIB/AAI/CAS.101
released:18 April 2017
duration of investigation: 3 years and 3 months
download report: AIB/AAI/CAS.101

Revision history:

Date/timeContributorUpdates
06-Jan-2014 08:02 harro Added
06-Jan-2014 08:03 harro Updated [Embed code]
06-Jan-2014 08:12 121.217.121.119 Updated [Embed code, Narrative]
06-Jan-2014 08:21 Alexander Wyche Updated [Narrative]
06-Jan-2014 08:52 Alexander Wyche Updated [Narrative]
24-Apr-2017 17:38 harro Updated [Source, Narrative]
24-Apr-2017 17:44 harro Updated [Time, Source, Damage]
25-Apr-2017 05:46 harro Updated [Narrative]

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