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Investigation of Bearing Failure in a Turbo Shaft Engine


Failure of a bearing in reduction gear box of a turbo shaft engine is investigated to determine its root cause. Teardown inspections followed by metallurgical investigations are carried out on the parts of the failed bearing. Severe flaking is observed on both inner and outer race as well as on balls. It indicates progressive fatigue due to overload. Insufficient clearance due to differential expansion of inner race and contraction of outer race due to heating and cooling, respectively, can also result in this type of phenomena. Maintaining oil discipline and using correct grade of oil at proper frequency can address these issues. A comprehensive engine-bearing prognostic approach may be followed utilizing available sensor information on-board the aircraft to predict bearing life and incipient bearing failure.

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John, S.K., Mishra, R.K., Hari, K. et al. Investigation of Bearing Failure in a Turbo Shaft Engine. J Fail. Anal. and Preven. 20, 34–39 (2020).

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  • Metal debris
  • Magnetic chip detector
  • Bearing
  • Flaking
  • Overload failure