Failure Analysis of Bearings and Gears of Accessory Gearbox of an Aero-engine

Madan, M and Sujata, M and Raghavendra, K and Gore, P and Bhaumik, SK (2011) Failure Analysis of Bearings and Gears of Accessory Gearbox of an Aero-engine. Project Report. National Aerospace Laboratories, Bangalore, India.

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A few components belonging to the engine accessory gearbox (EAGB) of an aeroengine, bearing serial No. 16-96-007 were forwarded to this laboratory for investigation. Examination revealed that there was fatigue failure in the gears on O6 and O8 axes and in the cage of the ball bearing on O7 axis. The primary failure in the EAGB has been identified to be the failure in the ball bearing located on the O7 axis and opposite to the fuel pump. The failure in the bearing was caused due to excessive stresses on the cage resulting from misalignment of the bearing on the gear shaft. Progressive failure in the ball bearing had also resulted in a chain of events in the transmission system along and in the vicinity of O7 axis. The failure of the cage in the bearing by fatigue resulted in non-uniform rotation and vibration in the O7 axis. This would have resulted in fretting wear on the mating splines of the quill shaft and the gear shaft. Also, the failure of the bearing had resulted in non-uniform meshing of the gears on either side of the O7 axis, i.e., O6 and O8 axes leading to fatigue failure in these gears. Once a few teeth of the gears have failed by fatigue, further damages were caused by impact. The other damages seen on various components of EAGB are secondary in nature. The materials of construction of all the components that have been sent for investigation were found to be as per specification or satisfactory for the intended application. No metallurgical abnormalities and/or lubrication deficiencies were found to be responsible for failure in any of the components.

Item Type: Monograph (Project Report)
Uncontrolled Keywords: Accessory gearbox;Gears;Bearings;Fatigue;Misalignment
Subjects: AERONAUTICS > Aeronautics (General)
CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Depositing User: Ms. Alphones Mary
Date Deposited: 12 Jul 2011 05:05
Last Modified: 12 Jul 2011 05:05

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