Failure analysis of control tube of a helicopter

Venkataswamy, MA and Sujata, M and Parameswara, MA and Suresh Kumar, M and Madan, M and Bhaumik, SK (2005) Failure analysis of control tube of a helicopter. Project Report. National Aerospace Laboratories, Bangalore.

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Abstract

Out of the five control tubes referred to NAL, four were found to have cracks/indication of cracks. Fractographic examination showed these cracks to be fatigue cracks of varying lengths (1.3 – 4.0 mm) and depths (30 – 90 m). There were no metallurgical and/or mechanical abnormalities responsible for the fatigue crack initiation. Also, there were no correlations between the service hours and crack occurrence/crack length/crack depth. Analysis shows that a number of unanticipated factors were collectively responsible for the early fatigue crack initiation. However, with the available evidences, it was not possible to identify these factors. Under the prevailing service conditions, the capability of the component appears to be marginally above the threshold value. It is recommended that the necessary design modification be incorporated to enhance the capability of the control tube per se so that enough safety factor is built in to take care of the unanticipated factors.

Item Type: Proj.Doc/Technical Report (Project Report)
Uncontrolled Keywords: Helicopter;tail rotor control tube;fatigue;unanticipated factors
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: Mrs Manoranjitha M D
Date Deposited: 05 Dec 2011 16:49
Last Modified: 05 Dec 2011 16:49
URI: http://nal-ir.nal.res.in/id/eprint/10121

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