ANA DH8C near Osaka on Jun 27th 2011, engine shut down in flight

Last Update: February 22, 2013 / 21:06:10 GMT/Zulu time

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Incident Facts

Date of incident
Jun 27, 2011

Classification
Incident

ICAO Type Designator
DH8C

Japan's Transportation Safety Board (JTSB) released their final report concluding the probable cause of the serious incident was:

In this serious incident, during the airplaneÂ’s after-takeoff climb, a section of the cooling ring in the combustion chamber of the engine was fractured due to the progress of fatigue cracks, and the fractured piece went downstream to damage the fast-rotating turbine blades and other parts, resulting in the circumferential turbine blade damage on several downstream turbine stages.

The JTSB reported that the aircraft was climbing through 6700 feet when a loud noise was heard from the left hand engine, the interturbine temperature (ITT) exceeded 950 degrees C and the engine lost power. The engine was shut down and the crew returned to Itami Airport.

A post flight inspection revealed blade damage along various turbine stages. The combustion chamber and high pressure turbine had accumulated 3,415 hours in 4,820 cycles since last overhaul/replacement with new parts. Examination revealed that the fuel nozzles showed no anomaly, the cooling ring attached to the combustion chamber outer line showed fatigue cracks in the circumferential and axial directions at several locations. A section of the ring was missing. All 38 high pressure turbine blades were fractured just above the platform as result of impact damage, all 53 low pressure turbine blades showed damage at the tips as result of impact, the 66 first stage and 71 second stage power turbine blades as well as vanes were fractured. The fractures were confirmed as impact damage, too, some intershaft rubbing was determined.

The JTSB analysed: "As the fracture surface of the bases of the HPT blades indicated the cause of fracture by impact, it is very likely that the missing section of the cooling ring was carried into the HPT area by the combustion gas to strike against the fast-rotating HPT blades or to be caught between the HPT blades and vanes. This generated fractured HPT blades and broken pieces and they further damage the other components leading to the whole circumference. The downstream LPT and PT stages were very likely damaged by broken fragments of the HPT blades and others coming from the upstream."
Incident Facts

Date of incident
Jun 27, 2011

Classification
Incident

ICAO Type Designator
DH8C

This article is published under license from Avherald.com. © of text by Avherald.com.
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