Failure analysis of input pinion of a helicopter

Madan, M and Sujata, M and Raghavendra, K and Bhaumik, SK (2011) Failure analysis of input pinion of a helicopter. Project Report. National Aerospace Laboratories, Bangalore, India.

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Abstract

A damaged input pinion, part No. 201P 636H 1302 201 bearing Sl. No. HDSN 527, belonging to Advanced Light Helicopter (ALH) was forwarded to this laboratory for investigation. Examination revealed loss of material by spalling on the loading flank of two teeth of the pinion. Spalling was resulted due to surface contact fatigue. It was discovered that there were rough machining marks on the flank of the teeth. The stress concentrators at these machining marks were responsible for the premature surface contact fatigue crack initiation in the teeth. Subsequently, the surface contact fatigue has manifested in the form of spalling leading to loss of material from the loading flank surface. Evidences also suggest that probably, the working load on the pinion was in the higher side. It is believed that this in conjunction with the stress concentrators in the form of machining marks has accelerated the surface contact fatigue crack initiation. Laboratory test results show that the material of construction of the pinion conforms to the design specification in terms of chemical composition, microstructure, surface hardness, case depth, and core hardness. No metallurgical abnormalities were found responsible for the failure of the pinion. A detailed analysis of the failure is presented in this report.

Item Type: Proj.Doc/Technical Report (Project Report)
Uncontrolled Keywords: Input pinion;Spalling;Hardness;Microstructure;Machining marks
Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Division/Department: Materials Science Division, Materials Science Division, Materials Science Division, Materials Science Division
Depositing User: Ms. Alphones Mary
Date Deposited: 06 Jul 2011 11:16
Last Modified: 06 Jul 2011 11:16
URI: http://nal-ir.nal.res.in/id/eprint/9272

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