Analysis of failed MGB II stage pinions of a helicopter

Bhaumik, SK (2003) Analysis of failed MGB II stage pinions of a helicopter. Project Report. National Aerospace Laboratories, Bangalore.

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Second stage planet pinions of main gear box (MGB) belonging to a helicopter that met with an accident were sent to the laboratory for analysis. Out of the nine pinions, four were found fractured into pieces, one collapsed and the remaining four had damages in the form of breakage and chewing of teeth. Fractographic examination revealed fatigue cracks in three pinions. Fatigue cracks were found to have originated at the tooth root radius regions, propagated progressively over about 90% of the tooth cross section before culminating in overload fracture. Excessive spalling was observed on the flanks of the pinion teeth indicating high contact stresses. The microstructure, hardness and case depth in the pinions were found to conform to specifications. From the analysis, it appears most probable that the pinions have failed due to high operating stresses.

Item Type: Monograph (Project Report)
Uncontrolled Keywords: Helicopter;MGB;pinions;fatigue;spalling;hardness; microstructure
Subjects: AERONAUTICS > Aeronautics (General)
CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Depositing User: Mrs Manoranjitha M D
Date Deposited: 07 Jul 2011 09:23
Last Modified: 07 Jul 2011 09:23

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