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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. Source


Nirmala S.,Regional Center for Military Airworthiness | Ananda C.M.,National Aerospace Laboratories, Bangalore
Proceedings - 2015 International Conference on Cognitive Computing and Information Processing, CCIP 2015 | Year: 2015

Communication in Micro Air Vehicles (MAV) swarm flying is challenging and critical for functional integrity of the swarm network. MAVs are deployed in groups to realise useful applications from MAV. Such mode of deployment of MAVs in-group demands dedicated and well defined communication method, protocol, simplified control and data paths along with the redundancy management to mitigate the failures. On the fly communication failures or complete system failure is addressed by dynamic reconfiguration of fellow MAVs to restructure the network as per Binary Search Tree network (BSTN). BST based network for swarm flying enables simplified and structured network with ordered, dynamic and unique data paths. Reconfiguration of MAV nodes in the BSTN is critical for continued swarm and hence completion of intended function. The paper presents the BST based network for MAVs, communication protocol, metrics for configuration, failure scenarios and redundancy management. © 2015 IEEE. Source


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. Source


Kale S.S.,Regional Center for Military Airworthiness Foundry and Forge | Raja V.S.,Indian Institute of Technology Bombay | Bakare A.K.,Regional Center for Military Airworthiness
Corrosion Engineering Science and Technology | Year: 2014

Stiffening of Al alloy aircraft structures with carbon fibre reinforced plastic laminate called 'patches' is considered as a viable option to enhance fatigue life. Interface so created between the reinforcement and Al alloy structure is potential site for crevice corrosion attack. Therefore, studies were conducted to investigate the interface corrosion behaviour of peak and two-step aged Al-Zn-Mg-Cu-Cr alclad alloy with and without the patch and examine the possibility to control the interfacial attack with the addition of cerium chloride inhibitor exposed to 3.5 wt-% NaCl solution for the durations of 2 and 168 h. Electrochemical impedance spectroscopy revealed that the interface attack was significantly reduced by the addition of 1000 ppm cerium chloride. The response of the peak and two-step aged alloy for such an addition was further investigated and found that the alloy under step aged condition behaves better than that of the peak aged condition.©2014 Institute of Materials, Minerals and Mining. Source


Mishra R.K.,Regional Center for Military Airworthiness | Srinivasan K.,Hindustan Aeronautics Ltd
Journal of Failure Analysis and Prevention | Year: 2016

Failure of low-pressure (LP) turbine rotor blades in low bypass military turbofan engines is a great concern for designers, manufactures, repair and overhaul agencies, operators, and airworthiness authorities. The present paper analyzes the LP turbine blade failure cases to determine its root cause. Forensic and metallurgical investigations are carried out on the failed blades. In most cases, the failure was originated from the leading edge and had propagated toward the trailing edge. Intergranular features and high oxidation on the fractured surface have been found as the cause of fatigue failure. Operation at elevated temperatures for considerable time was found responsible for these fatigue failures. Malfunction of fuel system, failure in control sensors, and nonuniformity in atomizer characteristics were the root cause of high temperature in turbine leading to the failure of blades. The paper also presents various remedial measures to address the blade failures from manufacturing and operational points of view. © 2016, ASM International. Source

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