Metallurgical Failure Analysis of Collector Pinion of a helicopter

Sujata, M and Madan, M and Venkataswamy, MA and Raghavendra, K and Bhaumik, SK (2011) Metallurgical Failure Analysis of Collector Pinion of a helicopter. Project Report. National Aerospace Laboratories, Bangalore, India.

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A failed collector pinion belonging to a helicopter was sent to the laboratory for analysis. Examination revealed chipping off of material at the circlip groove region. Fractographic study confirmed that the chipping off of material was by static overload. Metallurgical examination showed carburization of the entire collar of the circlip groove. Evidences suggest that there were localized contacts between the circlip face and the groove surface resulting in high loads at these contact points. Study shows that these localized contacts were due to inability of the hard carburized material to deform and make necessary adjustment for establishing contacts with the entire circlip face. It appears most probable that high notch sensitivity of the carburized material at the circlip groove in conjunction with the high localized load on the collar of the circlip groove was responsible for the failure. In view of this, it is recommended that suitable process modification be incorporated to avoid carburization in the circlip groove region.

Item Type: Monograph (Project Report)
Uncontrolled Keywords: Helicopter;Collector pinion;Overload failure;Carburization
Subjects: AERONAUTICS > Aeronautics (General)
CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Depositing User: Ms. Alphones Mary
Date Deposited: 12 Jul 2011 08:33
Last Modified: 12 Jul 2011 08:33

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