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Mishra R.K.,Regional Center for Military Airworthiness Engines | Muduli S.K.,Regional Center for Military Airworthiness Engines | Srinivasan K.,Hindustan Aeronautics Ltd Engine Division | Ahmed S.I.,Aeronautical Quality Assurance Engines
Journal of Failure Analysis and Prevention | Year: 2015

Failure of an inter-shaft bearing in an aero gas turbine engine is investigated to determine its root cause. Teardown inspections followed by metallurgical investigations are carried out on the parts of the failed bearing. None of the components of the bearing has shown any discolouration, wear, or overheating marks. But severe flaking is observed on one side of the outer raceway. It indicates progressive fatigue due to overload. Insufficient clearance due to differential expansion of inner ring and contraction of outer ring 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 such as rotor speed, vibration, lube system information, and aircraft maneuvers to predict bearing life and incipient bearing failure. © 2015, ASM International.


Mishra R.K.,Regional Center for Military Airworthiness | Ahmed S.I.,ORDAQA Engines | Srinivasan K.,Hindustan Aeronautics Ltd Engine Division
Journal of Failure Analysis and Prevention | Year: 2013

This paper investigates a bird strike incident of a military gas turbine engine. The jet pipe temperature of the engine shoot up and rotor speed reduced suddenly during takeoff roll. Long flame was noticed from the engine and aircraft crashed at runway end. Forensic analysis of remnants collected from flow passages confirmed the bird ingestion. Blockage of flow passages due to the presence of bird has led to engine surge and high gas temperature resulting in extensive damage of low pressure turbine module. The paper also proposes remedial measures to avoid such bird strikes during flight. © 2013 ASM International.


Mishra R.K.,Regional Center for Military Airworthiness | Srinivasan K.,Hindustan Aeronautics Ltd Engine Division | Thomas J.,Hindustan Aeronautics Ltd Engine Division | Vaishakhi N.,Hindustan Aeronautics Ltd | Bhat R.R.,Hindustan Aeronautics Ltd
Journal of Failure Analysis and Prevention | Year: 2014

Failure of low pressure turbine rotor blade in a low bypass turbofan engine is analyzed to determine its root cause. Forensic and metallurgical investigations are carried out on the blade failed. The failure has originated from the leading edge and has propagated towards the trailing edge. Intergranular features and high oxidation on the fractured surface are the cause of failure which is probably due to creep-stress rupture. This failure has caused extensive damages in low pressure turbine module and also in downstream modules as a secondary effect. Remedial measures are also suggested to prevent such failures. © 2014 ASM International.


Mishra R.K.,Regional Center for Military Airworthiness | Srivastav D.K.,Hindustan Aeronautics Ltd Engine Division | Srinivasan K.,Hindustan Aeronautics Ltd Engine Division | Nandi V.,Hindustan Aeronautics Ltd | Bhat R.R.,Hindustan Aeronautics Ltd
Journal of Failure Analysis and Prevention | Year: 2014

An aero gas turbine engine is investigated for foreign object damage. Extensive damage in the low pressure compressor and abnormal noise forced the engine to shut down. Metallic screw type foreign object debris was retrieved from air intake fairing. Chemical analysis of the metallic debris and failed surface of LP compressor blade show the smearing of blade material on the debris and debris material on compressor blade. This confirms that impact of metallic foreign debris has caused extensive damage to LP compressor blades. The paper presents the details of investigation carried out to assess the extent of damage and its root cause. Effective foreign object prevention and elimination program has also been suggested in the paper to address the FOD in aircraft engines. © 2014, ASM International.


Mishra R.K.,Regional Center for Military Airworthiness | Thomas J.,Hindustan Aeronautics Ltd Engine Division | Srinivasan K.,Hindustan Aeronautics Ltd Engine Division | Nandi V.,Hindustan Aeronautics Ltd | Bhat R.,Hindustan Aeronautics Ltd
Journal of Failure Analysis and Prevention | Year: 2014

Failure of low pressure turbine nozzle guide vane (NGV) in an aero gas turbine engine is analyzed to determine its root cause. Forensic and metallurgical investigations are carried out on the NGV failed as well as the failed components of the downstream modules. Failure in the cooling system in the NGV due to crack in the sealing plate was found to be the cause of NGV getting burnt. This failure has caused extensive damages in low pressure turbine modules. Remedial measures are also suggested to prevent such failures. © 2014, ASM International.

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