BA Airbus A319 : incident in Sept. 2009

The Danish Havarikommission HCL released their [Vous devez être inscrit et connecté pour voir ce lien] concluding:

The engine damage occurred as a result of a fracture in a non-Service Bulletin V2500-ENG-72-0487 standard compressor blade in stage 3 of the high-pressure compressor (HPC).

The fracture occurred as a result of high cycle fatigue initiated by wear and tear on the Clappers. This wear and tear allowed the blade to bend which consequently caused strain on the region of the blade platform bearing the heaviest load.

The HCL reported that the airplane was climbing about 12nm southsoutheast of Copenhagen's Kastrup Airport when the crew heard a loud bang, observed the aircraft to veer left, detected the left hand engine's (V2500) exhaust gas temperature increasing and received a number of ECAM messages associated with the failure of the left hand engine, a smell of smoke was noticed in the cockpit. The crew shut the left hand engine down, cabin crew observed clouds of smoke in the cabin prompting the crew to declare MAYDAY. After the engine was shut down the smoke dissipated and the emergency was downgraded to PAN. The airplane returned to Copenhagen for a safe landing on runway 04R.

The left hand engine had accumulated 14,246 hours.

A post flight inspection found small particles and metallic fragments in the turbine and engine exhaust pipe of engine #1. Subsequent inspections found a blade missing from stage 3 of the high pressure compressor, only the root of the blade remained in its slot. Secondary damage was observed at all remaining 30 blades of stage 3, the stage 4 stator vanes and from stage 6 to stage 12 of the high pressure compressor. No damage was observed in the low pressure compressur, high pressure turbine and low pressure turbine.

Laboratory analysis concluded that the blade had cracked as result of high cycle fatigue. The crack originated in the area of highest stress and worn Clappers. This scenario was consistent with previous blade fractures observed between 2001 and 2005.

In June 2005 the manufacturer had introduced a new blade design with modified Clappers to address the issue of worn Clappers and issued an associated service bulletin V2500-ENG-72-0487. By January 2010 83% of all engines had received the modified blades. In June 2005 the manufacturer also issued a non-modification SB establishing a revised inspection schedule for non-modified blades.

The incident engine had not been modified, during an inspection in November 2008 the inspection interval was reduced to 100 cycles according to the condition of the clappers indicating amber criterion, the engine accumulated 1600 hours since. The last inspection prior to the incident was on Sep 12th 2009.

The HCL annotated that the non-modification SB that wear and tear of Clappers deteriorating to or below the amber criterion means the engine should be detached within the next 500 cycles. Following that recommendation would have prevented the engine failure, however being a recommendation there was no requirement to replace the engine.