SELECT STUDY OF PROCUREMENT PROCESS AND AVAILABILITY IMPROVEMENT IN
MILITARY AVIATION
by
RAJIV NANDAN RAI
Department of Mechanical Engineering
Submitted
in fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY
to the
INDIAN INSTITUTE OF TECHNOLOGY DELHI
DECEMBER 2013
CERTIFICATE
This is to certify that the thesis entitled “Select Study of Procurement Process and Availability Improvement in Military Aviation” submitted by Mr. Rajiv Nandan Rai to the Indian Institute of Technology Delhi, for the award of the degree of Doctor of Philosophy is a record of the original bonafide research work carried out by him under my guidance and supervision. The results contained in it have not been submitted in part or full to any other institute or university for the award of any degree or diploma.
Place: New Delhi (Dr. NOMESH BOLIA) Date: Assistant Professor
Department of Mechanical Engineering Indian Institute of Technology Delhi New Delhi- 110016, (INDIA)
i
ACKNOWLEDGEMENTS
The thesis is inspired by my 18 years of hard work in the field of aircraft maintenance in military aviation. The motivation for the research work is derived from the limitations of the existing procurement process, reliability analysis and plant performance measurement systems in military aviation. The research work was undertaken at Indian Institute of Technology, Delhi under the PhD study program for Industrial Engineering.
The work was accomplished under the supervision of Dr. N. Bolia and under the guidance of Professor A. D. Gupta, Professor Dr. O. P. Gandhi and Dr.
M. S. Kulkarni.
Firstly I would like to thank Late Group Captain Sunil Kumar whose inspiration, motivation and endless love drove me to undertake the research work.
I would like to express my sincere gratitude to all the people who have provided me advice, help, cooperation during the course of the study, particularly Dr.
Nomesh Bolia who devoted himself tirelessly to provide required guidance for accomplishment of the research work. I am extremely thankful to Dr. M. S.
Kulkarni for always providing the guidance and specialist opinion on the subject. I also extend my gratitude to Professor A. D. Gupta and Professor O. P. Gandhi for providing invaluable guidance during the course of research work.
ii I dedicate this work to my most beloved parents who are no more but their blessings have always been there with me. I would forever be grateful to my wife Neena for her unconditional love, support and patience during the PhD period, for encouraging me despite her numerous commitments. I would also treasure the love of my son Sunny and daughter Shakshi who at times sacrificed the need for my help in their own studies to permit me to complete my work.
I would be equally grateful to all those who have been associated with my study, and helped me in shaping my ideas and rolling them to practicality, the editors and the reviewers of my papers and the reviewers of my thesis.
(RAJIV NANDAN RAI)
iii
ABSTRACT
Presently military aviation (MA) in developing countries, including India, lacks an effective framework which can provide scientific approach to procurement process, maintenance and reliability engineering related problems.
Implementation of scientific methodologies and models for procurement process, reliability and maintainability (R&M) analysis in MA would be a meaningful step since this can aid in better fleet management for enhanced operational capability.
This research work is mainly focused on developing scientific methodologies for the acquisition process followed by availability improvement in MA. Motivated by the limitations encountered by the present system, four objectives are formulated which addresses all the limitations inherent in the present system by developing models and methodologies for various processes starting from acquisition followed by maintenance. A literature survey is presented on weapon systems capability evaluation (WSCE), imperfect repairs, modified failure modes and effects analysis (FMEA) and throughput (TH) analysis. The research gaps that emerge out of the literature review are deliberated. To develop a framework for the procurement process, the selection of alternatives for the procurement of weapons is discussed with the help of the analytic network process (ANP) approach. The thesis then discusses a hierarchical weapon systems valuation model framework and applies analytic hierarchy process (AHP) in establishing two major indices used to evaluate Air Power effectiveness (APE) and AP potential (APP). They are termed Air Power index (API) and Air Power value (APV). Using API and APV as tools, an optimization model for raising an ACU
iv considering several representative constraints is developed. All models are demonstrated with the help of Illustrative examples.
The potential available for a combat force at any point of time is dependent on the number and operational readiness of the weapon systems. Thus to enhance APP by increasing APV either procure more weapons can be procured or the availability of the weapon systems can be improved. In MA, depots confront situations of declaring certain components as High Failure Rate Components (HFRC) to shortlist them for reliability improvement and subjecting them to reviewed maintenance actions. Presently this is done mainly through intuition, experience or based on the number of unscheduled failures at repair depots. The thesis develops methodologies for deciding a threshold based on availability at which the component can be rendered HFRC. Availability based methodology is also developed to designate HFRC by considering the dominant failure modes of the equipment. Further optimization methodologies based on downtime are also developed to review the overhaul policy for the HFRCs.
Generalized Renewal Process (GRP) is used to model repairs and the authenticity of all the developed methodologies is tested on three variants of an aero engine working under field conditions. Further, a methodology is developed to estimate initial RPN by using repair effectiveness index (REI) of GRP and then to reduce RPN of the failure modes (FM) by reducing probability of occurrence (O) with the help of REI estimated through GRP.
v Lastly, suggestions are made for reduction of the time taken for overhaul by enhancement of the present throughput of the repair and overhaul (RAOH) line. The suggestions are based on statistical modeling of the repair processes of three critical components of the aero engine and identifying the bottlenecks in the repair processes followed by recommendation of remedial measures.
KEYWORDS:
Air Power, Air Power Potential, Air power value, Air Combat Unit, Analytic Hierarchy Process, Analytic Network Process, Attack, Defence, Generalized Renewal Process, Repairable Systems, Monte Carlo Simulation, High Failure Rate Component, Military Aviation, Non-homogeneous Poisson process, Renewal Process, Time between Overhaul, Availability, Failure Modes, Imperfect Repair, Failure Modes and Effects Analysis, Repair Effectiveness Index, Throughput, Cycle time, Work in Process.vii
TABLE OF CONTENTS
S. No. Title Page No.
Acknowledgements i
Abstract iii
Table of Contents vii
List of Figures xi
List of Tables xiii
List of Abbreviations xv
Notations xix
Chapter I INTRODUCTION 1-14
1.1 Background 1
1.2 Present Acquisition process 2
1.3 Maintenance 3
1.4 Present System of Reliability Analysis in Military Aviation
4 1.4.1 Present System of Plant Performance Assessment at
Depots
5
1.5 Limitations of the Present System 5
1.5.1 Limitations of the Present Acquisition Process 6 1.5.2 Limitations of the Present System of Reliability Analysis 7 1.5.3 Limitations of the Present Plant Assessment at Depots 7
1.6 Objectives 8
1.7 Relevance 9
1.8 Thesis Road Map 10
1.9 Case description 11
1.10 Thesis Plan 12
Chapter II LITERATURE SURVEY AND RESEARCH GAPS 15-40 2.1 Literature Review on Weapon Systems Capability
Evaluation.
15
2.2 Literature Review on Imperfect Repairs. 18
2.2.1 Repairable Systems: Arithmetic Reduction of Age Models 22
2.2.2 GRP Solution Techniques to Kijima Models 26
2.2.3 Maintenance Policies using Kijima Virtual Age Model 30 2.2.4 Miscellaneous Application on Kijima Virtual Age Model 32 2.2.5 Repairable Systems: Arithmetic Reduction of Intensity 32
viii Models
2.3 Literature Review on FMEA. 35
2.4 Literature review on TH Analysis. 37
2.5 Research gaps 39
Chapter III INTEGRATED APPROACH TO WEAPON PROCUREMENT SYSTEMS
41-66
3.1 Introduction 42
3.2 The Proposed Model for Selection of Alternatives 45
3.2.1 The Analytic Network Process Model 46
3.3 Air Power Index and Air Power value Estimation 51
3.3.1 The Analytic Hierarchy Process Model 52
3.3.2 Air Power Index Estimation 52
3.3.3 Sample Air Power Index Estimation 55
3.3.4 Air Power Value Estimation. 56
3.4 Formation of an Air Combat Unit 60
3.4.1 Attack model 61
3.4.2 Defence Model. 62
3.4.3 Illustrative Example 63
Chapter IV AVAILABILITY BASED HIGH FAILURE RATE COMPONENT ANALYSIS
67-101
4.1 Introduction 67
4.2 Need for HFRC Threshold 70
4.3 Repairable Systems 71
4.4 Basic Analysis Approaches for Repairable Systems 72 4.4.1 Renewal Process and Homogeneous Poisson Process 72
4.4.2 Non-Homogeneous Poisson Process 73
4.4.3 Generalized Renewal Process 76
4.5 Problem Formulation and Methodology 76
4.5.1 Assumptions 76
4.5.2 Virtual Age and Repair Effectiveness (Kijima Model I) 77 4.5.3 Maximum Likelihood Estimators for GRP Parameters 78
4.5.4 Failure-Terminated GRP MLEs 79
4.5.5 Expected Number of Failures Estimation in GRP. 79
4.5.6 First Overhaul Cycle 81
4.5.7 Availability Based Criteria for HFRC 82
4.5.8 Review of Overhaul Cycle 85
4.6 Results and Analysis 86
ix
4.6.1 Variant 1 Aero Engines 86
4.6.2 Variant 2 Aero Engines 88
4.6.3 Variant 3 Aero Engines 88
4.7 Availability Based HFRC Threshold Model Considering Failure Modes
89
4.8 Revised Maintenance Strategy for HFRCs 93
4.8.1 Dominant Failure Modes Identification of the Aero Engine
94 4.8.2 Reviewed Time between Overhaul Model considering
Failure Modes
95
4.9 Results and Discussion for FM Approach 96
4.9.1 Failure Mode Wise Results and Analysis 97
Chapter V MODIFIED FMEA MODEL WITH REPAIR EFFECTIVENESS FACTOR
103-123
5.1 Introduction 104
5.2 Failure Modes and Effect Analysis (FMEA) 106
5.2.1 System Definition 106
5.2.2 Identification of Failure Modes 107
5.2.3 Determination of cause 107
5.2.4 Assessment of effect 108
5.2.5 Classification of Severity 108
5.2.6 Estimation of Probability of Occurrence 109
5.2.7 Detection 110
5.2.8 Computation of Conventional RPN 110
5.2.9 Failure Mode Classification Matrix 111
5.2.10 Determination of Corrective Action 112
5.3 Problem Formulation 112
5.4 Performance Parameters Estimation 112
5.5 Estimating RPNs through the Proposed Approach 113 5.6 Advantage of Suggested Algorithm over Conventional
Method
115
5.7 Results and Discussion 115
5.7.1 Estimation of GRP Estimators of the Identified Failure Modes
115 5.7.2 Estimation of RPNs with Suggested Algorithm 116
5.8 Corrective Actions 118
Chapter VI THROUGHPUT ANALYSIS OF THE OVERHAUL 125-149
x LINE OF A REPAIR DEPOT.
6.1 Introduction 126
6.2 Basic Definitions, Parameters and Relationships 128
6.3 Variability 130
6.3.1 Measures and Classes of Variability. 130
6.3.2 Causes of Variability 131
6.3.3 Variability from Preemptive Outages (Breakdowns) 131
6.3.4 Variability in Flows 133
6.3.5 Variability Interactions-Queueing 134
6.3.5.1 The M/M/1 Queue. 134
6.3.5.2 The G/G/1 Queue. 134
6.3.6 Process Batching 135
6.4 System Flow and Parameters 136
6.5 System Analysis and Discussion 140
6.5.1 Component 1: LPCR Blades 141
6.5.2 Component 2: CCOC 145
6.5.3 Component 3: LPTR Blades 147
Chapter VII CONCLUSION 151-160
7.1 Future Extensions of the Research Work 154
7.1.1 Pure Attack 154
7.1.2 Pure Defence 156
7.1.3 Attack and Defence. 157
7.2 Future Extensions of the Research Work on Modeling REI
References 161
Appendices 173
Publications Based on this Research Work 231
Author Biography 233
