Analysis of parts of an aeroengine and a few wreckage items involved in the accident of an aircraft

Suresh Kumar, M and Madan, M and Venkataswamy, MA and Sujata, M and Kannan, CR and Bhaumik, SK (2006) Analysis of parts of an aeroengine and a few wreckage items involved in the accident of an aircraft. Project Report. National Aerospace Laboratories, Bangalore, India.

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Abstract

The fractured HPTR disc belonging to an aeroengine retrieved from the wreckage of an aircraft was investigated. Fractographic examination showed that the HPTR disc had failed by fatigue resulting in extensive damage to the engine followed by which the aircraft had crashed onto the ground. There was multiple fatigue crack initiation at the fillet of the dovetail rim. After initiation, these cracks have propagated simultaneously and joined together to form a major crack front. The resulting crack had then propagated progressively through the thickness leading to fracturing of a part of the disc. Fluorescent dye penetrant inspection (FPI) carried out on the remaining portion of the disc showed presence of enumerable number of fatigue cracks at the fillet of the dovetail rim at several locations on the circumference. The fatigue cracks were found to have initiated at the fillet in between the cooling holes. Evidences suggest that fatigue was stress related and the crack initiation was resulted due to presence of stress raisers in the form of rough machining marks. The HPTR disc material was found to conform to specification. Microstructural study and hardness survey did not reveal any metallurgical degradation of the disc material due to usage or creep damage. The other wreckage items sent for investigation showed damages which are secondary in nature and were caused after the primary failure i.e., fatigue fracture of the HPTR disc. Evidences do not suggest extensive fire in the engine. It appears that after fracturing of the disc, the rim portion was thrown out under the centrifugal force, which pierced through the engine casing. The projectile sheared off the hydraulic pipeline in the vicinity resulting in immediate fire in the aircraft. The debris of the fuel tanks did not show any signatures of explosion. The fractographic features and failure patterns suggest that the fuel tanks have fractured under impact forces.

Item Type: Proj.Doc/Technical Report (Project Report)
Uncontrolled Keywords: Aircraft accident;HPTR disc;Fatigue;Stress raisers;Machining marks
Subjects: AERONAUTICS > Aeronautics (General)
CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Division/Department: Materials Science Division, Materials Science Division, Materials Science Division, Materials Science Division, Materials Science Division, Materials Science Division
Depositing User: Ms. Alphones Mary
Date Deposited: 26 Jul 2011 16:43
Last Modified: 26 Jul 2011 16:43
URI: http://nal-ir.nal.res.in/id/eprint/9632

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