Airworthiness certification Short

Airworthiness Certification of Fighter Aircraft

AIRWORTHINESS CERTIFICATION OF FIGHTER AIRCRAFT

K NagarajFormer Chief Executive (Airworthiness)

Centre for Military Airworthiness and Certification (CEMILAC)

Bengaluru, India

Defence Research and Development OrganisationMinistry of Defence, New Delhi – 110 011

2015

DRDO MONOGRAPHS/SPECIAL PUBLICATIONS SERIES

AIRWORTHINESS CERTIFICATION OF FIGHTER AIRCRAFT

K Nagaraj

Series EditorsEditor-in-Chief Assoc. Editor-in-Chief Editor Asst. EditorGopal Bhushan Dr GS Mukherjee Anitha Saravanan Kavita Narwal

Editorial Assistant Gunjan Bakshi

Cataloguing-in-Publication

Nagaraj, K


DRDO Monographs/Special Publications Series1. Fighter aircraft 2. Airworthiness I. Title II. Series623.746.3:629.7.017

© 2015, Defence Research & Development Organisation, New Delhi – 110 011.

ISBN 978-81-86514-84-9

All rights reserved. Except as permitted under the Indian Copyright Act 1957, no part of this publication may be reproduced, distributed or transmitted, stored in a database or a retrieval system, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the Publisher.

The views expressed in the book are those of the author only. The Editors or the Publisher do not assume responsibility for the statements/opinions expressed by the author.

Cover Design Printing MarketingAnjan Kumar Das SK Gupta Rajpal Singh

Published by Director, DESIDOC, Metcalfe House, Delhi – 110 054.

Contents

Foreword xiPreface xiiiAcknowledgements xvTerminology and Institutions xviiList of Acronyms xxiIntroduction xxix

CHAPTER 1: TECHNOLOGY DEVELOPMENT 1

CHAPTER 2: PROJECT INITIATION AND DEVELOPMENT 3 2.1 Feasibility Study 32.2 Project Definition 5

CHAPTER 3: CONCEPTS OF AIRWORTHINESS CERTIFICATION 93.1 Introduction 93.2 Airworthiness Certification 9

CHAPTER 4: AB-INITIO DESIGN, DEVELOPMENT, AND 13 PRODUCTION 4.1 Introduction 134.2 Pre-requisites 134.3 Evaluation of Design 144.4 Review Systems 164.5 Methodology to Deal with Defects During Development 174.6 Transition from Development to Production 20

CHAPTER 5: FACETS OF AIRCRAFT DESIGN 23

CHAPTER 6: AERODYNAMICS 256.1 Air 256.2 Pressure 25

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6.3 Density 256.4 Airflow 276.5 Aircraft Aerodynamics 286.6 Aerodynamic Forces in Flight Manoeuvres 436.7 Stability and Handling of Aircraft 48

CHAPTER 7: STRUCTURES 657.1 Configuration Study 657.2 Air Load Estimation and Wind Tunnel Tests 657.3 Structural Design and Analysis 677.4 Static Strength Analysis 677.5 Fuselage Analysis 677.6 Wing Analysis 687.7 Horizontal Tail Analysis 697.8 Vertical Tail Analysis 697.9 Validation of the Total Aircraft 787.10 Excitation Procedures 827.11 Aerodynamic Effects 87

CHAPTER 8: ELECTRICAL SYSTEM 918.1 Overview of Aircraft Electrical System 918.2 Wiring 938.3 Electro Magnetic Compatibility 948.4 Electrical Power System Requirements 958.5 Load Characteristics 98

CHAPTER 9: HYDRAULIC SYSTEM 101

CHAPTER 10: FLIGHT CONTROL SYSTEM 10710.1 Flight Control Actuation System 11310.2 System Design 11310.3 Electro-Hydraulic Servo-Valves 11410.4 Direct Drive Valves 11410.5 Comparison of EHSV with DDV Servo Actuators 11410.6 Built-in Test/Redundancy Management 119

CHAPTER 11: NAVIGATION SYSTEM 12111.1 Doppler Navigation System 12211.2 Very High Frequency Omni Range 126

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11.3 Tactical Air Navigation System 12811.4 Inertial Navigation Systems 12811.5 Automatic Direction Finder 130

CHAPTER 12: COMMUNICATION SYSTEM 13112.1 Very High Frequency/Ultra High Frequency Technology 13112.2 Radio Communication 13112.3 Antennae 13312.4 Sources of Noise 13512.5 Reducing the Effects of Noise and Interference 136

CHAPTER 13: LANDING GEAR SYSTEM 139

CHAPTER 14: FUEL SYSTEM 145

CHAPTER 15: OXYGEN SYSTEM 14715.1 On-board Oxygen Generation Systems 149

CHAPTER 16: ENVIRONMENTAL CONTROL SYSTEM 15316.1 Bleed Subsystem 15416.2 Air Conditioning Subsystem 15416.3 Cabin Distribution Subsystem 155

CHAPTER 17: BRAKE PARACHUTE SYSTEM 157

CHAPTER 18: WEAPON SYSTEM 15918.1 Fixed Gun Installation 16018.2 Tests Required to Prove the Gun Installation 16218.3 Integrated Weapon System 167

CHAPTER 19: ESCAPE SYSTEM 16919.1 Means of Escape 169

CHAPTER 20: SOFTWARE SYSTEM 17320.1 Software Development Process 17320.2 Software Development Activities 17420.3 Process Improvement Models 17720.4 Formal Methods 178

CHAPTER 21: PROPULSION SYSTEM 17921.1 Thrust Augmentation 180

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CHAPTER 22: STANDARDS AND SPECIFICATIONS 18322.1 Types of Specifications 18322.2 Implementation of Specifications/Standards 185

CHAPTER 23: DRAWINGS 18723.1 Drawing Standard 18723.2 Types of Drawings 19023.3 Master Record System for Drawings 191

CHAPTER 24: DESIGN EVALUATION FOR AIRWORTHINESS 19324.1 Introduction 19324.2 Aerodynamics 19524.3 Electrical System 20524.4 Systems Clearance 21024.5 Hydraulic System 22124.6 Installation 24224.7 Ergonomics 24824.8 Aircraft Lighting 24924.9 Life Support Systems 24924.10 Avionics Architecture and Avionics Subsystems 25224.11 Armament/Stores Integration 25424.12 Safety Interlocks 25524.13 Computer 257

CHAPTER 25: SIMULATION 261 25.1 Types of Simulators 26125.2 Techniques of Simulation 262

CHAPTER 26: SAFETY ASSESSMENT OF AIRCRAFT SYSTEMS 26526.1 Hazard Risk Assessment 26726.2 Flight Worthiness Evaluations 26726.3 Software Safety Assessment 26826.4 Software Development: Safety Assessment 270 26.5 New Hazards 271

CHAPTER 27: GROUND TESTS 27527.1 Aerodynamics 27627.2 Armament Stores 28027.3 Ground Firing Tests 283

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CHAPTER 28: DOCUMENTATION 28928.1 General Requirements 28928.2 Structures 29028.3 Flight Control System 29128.4 Propulsion and Propulsion Systems 29328.5 Pilot–Vehicle Interface 29428.6 Avionics 29528.7 Electrical System 29628.8 Computer and Software 29728.9 Armament Stores 298

CHAPTER 29: FLIGHT CLEARANCE CERTIFICATE 30129.1 Introduction 30129.2 Standard of Preparation of Aircraft 302

CHAPTER 30: FLIGHT TESTS 30730.1 Flight Test Instrumentation 30730.2 Flight Tests 30830.3 Evaluation of Test Results and Acceptance 310

CHAPTER 31: RELEASE TO SERVICE 317

CHAPTER 32: CONTINUED AIRWORTHINESS 31932.1 Modifications 32032.2 Aircraft Level Aspects 32332.3 Weapon System Augmentation 32432.4 Licence-Built Aircraft 328

CHAPTER 33: INCIDENTS, DEFECTS, AND ACCIDENT 331 INVESTIGATION 33.1 Aircraft Accidents 331

CHAPTER 34: INDIGENOUS DEVELOPMENT 33534.1 Items Having Licence Agreement 33634.2 Approval of Non-Critical Items 33634.3 Consumables: Approval of Fuel, Oil, and Lubricants 339

CHAPTER 35: LIST OF DOS AND DON’TS 34335.1 Dos 34335.2 Don’ts 345

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CHAPTER 36: CERTIFICATION IN FOREIGN COUNTRIES 34736.1 United States of America 34836.2 United Kingdom 34836.3 France 34936.4 Russia 35036.5 Conclusions 350List of References 353Index 363

Preface

This monograph is written for use by students pursuing the aeronautical engineering degree course; fresh entrants into the certification group; personnel engaged in the design, development of fighter aircraft with the objective of meeting the user’s requirement; R&D scientists; certification groups; and user services.

Airworthiness means different things to different people. It is an essential prerequisite if the product has to be of utility to the user services for deployment in an operational scenario, in both military and civilian usage. However, unlike in the civilian sector, airworthiness certification has not got the recognition that is the due of such a vital and important subject in the military sphere.

This publication highlights the aspects of airworthiness certification that have to be assimilated into all facets of design, development, production and service life cycle of an aircraft and airborne store. It is of particular significance during design and development, since a product can only be as good as it has been designed, and all other factors will only help to achieve the capabilities built into the product by design. This monograph also attempts to bring out the fact that if corrective actions are required, they can be extremely difficult, if not impossible, to introduce and implement at later stages, due to the constraints of time and cost. Thus, the deficiency may have to be carried forward till the aircraft is phased out of service.

The certification personnel will have to meet several challenges in the concurrent design, development and certification scenario. This publication, therefore, deals in some depth with the design and design evaluation aspects. It also brings in the practical experience in aircraft system design of the author, who had the privilege of working for five years in the HF-24 design team of Dr Kurt Tank, the famous German designer, who set up a design team at the invitation of the then Prime Minister, Pandit Jawaharlal Nehru.

It is an extremely challenging and rewarding experience to be involved in an ab initio design and development project, and to process the activities of concurrent certification and accord flight clearance for the first flight and a block of initial flights. This task is all the more exciting if the aircraft incorporates state-of-the-art technologies for which certification standards are scant and have to be evolved

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as the work progresses. The author was privileged to shoulder this awesome responsibility and accord such a flight clearance for the Light Combat Aircraft (LCA).

The material presented in this monograph is, out of compulsion, only a small part of the mammoth activity that goes under the generic title of Airworthiness and Certification. The scope of activities and nuances involved are too vast and intensive to be consolidated in one publication. What has been presented, therefore, is of such a nature and depth that will enable the interested and the practitioner alike to grasp the overall approaches to aircraft design and airworthiness certification, and to benefit from the experience of the author in this field for over three-and-a-half decades. The author will derive immense pleasure and feel rewarded if a large number in the aeronautical community read the book and benefit from the contents.

Bengaluru K Nagaraj Former CE (Airworthiness)

Centre for Military Airworthiness and Certification

Acknowledgements

A work of this scope and magnitude has to draw upon the knowledge, experience and expertise of several distinguished people, who have specialised and worked in the specific areas and on several projects. The author has been very fortunate in getting the cooperation, wholehearted support and generous help from Shri S Krishnasamy, former Chief Executive, CEMILAC, and Director, ADRDE, Agra, on aerodynamics and Late Shri VK Kalyanam, former Associate Director, CEMILAC, on aircraft structures. The author expresses sincere thanks to these gentlemen in this regard. The author wishes to place on record his thanks to Dr Raghothama Rao for his painstaking and meticulous effort in proofreading of the document.

The project has been made a reality by DESIDOC, DRDO, Delhi. The author sincerely thanks Shri Gopal Bhushan, Director, DESIDOC and gratefully acknowledges with thanks the efforts of the officers and staff of DESIDOC and in particular Smt Anitha Saravanan, Head, Monographs.

A publication of this magnitude and content requires a good deal of effort in typing, compilation, data collection, proofreading, countless number of revisions and other miscellaneous types of work. The author gratefully acknowledges with thanks the efforts of Shri Edwin Oliban, who has helped in preparing this document as per schedule and in an extremely presentable form.

K Nagaraj

Terminology and Institutions

1. ASR/NSQR/GSQR/ISQR: The ASR/NSQR/GSQR/ISQR is a document which describes, in qualitative terms, requirement for an equipment or system for IAF, Indian Navy, Indian Army, and Inter Services, respectively.

2. CEMILAC/RCMAs: Centre for Military Airworthiness and Certification is responsible through its Regional Centres for Military Airworthiness, for all activities leading to certification of fighter/transport aircraft, helicopters, engines, systems, airborne equipment, software, mid-life upgrades/life extension programmes of indigenous/license production/bought out aircraft, indigenously developed airborne stores, FOL, continued airworthiness activities like defect/incident/accident investigation, and approval of corrective actions through SIs, STIs, UONs, and modifications.

3. Certificate of Design: The Certificate of Design is the document which certifies that the store complies with all the requirements laid down in the Technical Specification with exceptions quoted therein.

4. Chief Resident Engineer/Regional Director: The heads of RCMAs are designated as Chief Resident Engineers or Regional Directors.

5. Chief Resident Inspector: The Chief Resident Inspector is the resident representative of the Director General Aeronautical Quality Assurance to ensure quality assurance of the stores during design, development and production phases.

6. Design Approved Agency: Design Approved Agency is an agency whose design/development department has been approved by the Chief Executive, CEMILAC as competent to carry out design, development, modification, indigenous substitution of a particular class of stores/material/equipment, and/or formulate Statement of Work (SOW), Prime Item Development Specification (PIDS), Critical Item Development Specification (CIDS) and software related documents, etc.

7. Design Authority: Responsible for the detailed design and development of the aircraft, aero engines, systems/software/equipment/materials/components, etc. The design authority is the Design Department of the Development Agency or any Design Approved Agency or R&D establishment.

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8. Design and Development Agency: Undertakes design and development of aircraft, aero engines, systems, software, equipment, materials, etc. The design and development agency may be a public sector undertaking, government R&D organisation, R&D laboratories, agencies created by the government from time to time for such purposes, or private sector firms.

9. Development Contracts: This is a contract placed on a development agency for development of an aeronautical store on the basis of service requirements.

10. DGAQA/RDAQA: Directorate General of Aeronautical Quality Assurance through Regional Directorate of Aeronautical Quality Assurance is the approving authority for quality assurance during manufacture and quality assurance for all the activities listed under CEMILAC.

11. Main Contractor: A development and/or production agency entrusted with the total responsibility for development and/or production of aircraft/aero engines/systems/software/equipment/components/material, etc.

12. Minor and Major Airborne Equipment: Airborne equipment is classified as minor and major. Classification into major and minor equipment, critical, and non-critical shall be described by the main contractor in consultation with RCMA. Minor items are those which do not affect the safety and interchangeability aspects of the aircraft maintenance and operation. Proprietary items that are being imported and constitute only forming and machining operations may also be considered as minor equipment. Electrical black boxes; electro-mechanical, hydraulic, and pneumatic components; brake pads; etc., shall be considered as major items.

13. Production/Limited Series Production: Production refers to bulk production at the production agency or Limited Series Production (LSP) carried out either at the development agency or at the production agency. This also refers to the overhaul or repair of the aircraft or airborne stores.

14. Provisional Clearance: A Provisional Clearance could be issued by one of the RCMAs for a limited period, pending final approval by CEMILAC. A Provisional Clearance is issued to the effect that the store under development meets all the laid-down specifications and test requirements with the exceptions stated therein. The Provisional Clearance is issued because documentation is pending, or because some of the long cycle life tests (such as fatigue test) are pending, or because of the necessity to obtain, from flight tests, some results which cannot be obtained from ground tests. There is no difference between a Provisional Clearance and a Type Approval in so far as the safety of the aircraft or airborne store is concerned.

Terminology and Institutions

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15. Quality Assurance Approved Firm: Quality Assurance Approved Firm is a firm whose quality assurance organisation has been approved by DGAQA as competent to carry out quality assurance during manufacture/overhaul/repair/storage of aircraft/aero engines and its associated equipment, accessories, and other aircraft stores. The terms and conditions for approval are given in DGAQA, Ministry of Defence document ‘Approval of Firm’s Inspection Organisation/Department’ and also ‘Quality Control System Requirements for Industry’, JSS 0254-01 April 1983.

16. Regional Centre for Military Airworthiness: Regional Centre for Military Airworthiness is a unit of CEMILAC, which acts on behalf of CEMILAC. It deals with all aspects of technical clearance of the airborne stores during design, development, production, and in-service phase. In such places where there is no establishment of RCMA, authority may be delegated to Visiting Technical Officers (VTOs) of CEMILAC.

17. Subcontractor: Any agency, including PSU, private sector, R&D institutions, etc., identified by the main contractor for the development and/or manufacture of a specific airborne store. The subcontractor is responsible to the main contractor.

18. Type Approval: Type Approval is a certificate issued by the approving authority, i.e., Chief Executive, CEMILAC to the effect that the store under reference meets all design specifications and test requirements laid down by CEMILAC. The Type Approval is issued after the Design Authority/Main Contractor submits a full Type Record with all the relevant documents to the satisfaction of CEMILAC.

19 Type Record: Type Record is a document giving a description of the store; its functional performance characteristics; summary of strength and other calculations along with reserve factors, environmental envelope of operation and storage of the store; results of all the tests including environmental, functional and performance tests; weight data; list of applicable drawings; and the certificate of design. It includes all documents and specifications approved by CEMILAC, information on dimensions, materials, and processes necessary to define the structural strength of the aeronautical product. It should also indicate instructions for continued airworthiness of the product, operating limitations, and other information for the safe operation of the product.

20 Technical Specification: Technical Specification is a document laying down design and performance characteristics of the stores. The technical specification shall contain full details of the equipment, standard of the main

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store, the specifications/standards followed in the design and manufacture, the environmental conditions, interface and integration requirements, besides performance and functional requirements.

21. User Acceptance: Acceptance of the airborne store for service use and end use requirements will be the responsibility of the concerned services.

Introduction

The aeronautical industry took shape in India in 1940, with the establishment of Hindustan Aeronautics Limited (HAL) as a private enterprise by late Walchand Hirachand on land generously sanctioned by Shri Krishnarajendra Wodeyar, the then king of Mysore, for overhauling USAF aircraft. It was consolidated through takeover by the Government of India in 1942. The impetus for indigenous design and development was given by the HT 2 basic trainer project. Although this all-metal aircraft was primarily meant for use by the Indian Air Force, it was certified by DGCA, under the overall guidance of Dr S Neelakantan, since there was no Military Certification Agency in existence at that time. All design clearance activities were undertaken by HAL.

The Directorate of Technical Development and Production (Air) [DTD&P (Air)] was subsequently formed by the Ministry of Defence, Government of India, under the leadership of Dr S Neelakantan, to look after the Military Aircraft Airworthiness Certification aspects, including overseeing of company inspection. The first branch office of DTD&P (Air) was started in 1958 at Bengaluru within the premises of HAL, structured similar to airworthiness groups in the UK. The design and inspection related functions were separated in 1960, and entrusted to Chief Resident Engineer (CRE) and Chief Resident Inspector (CRI) respectively, in view of the increased aeronautical activities taken up in the country. CRE (Engines) was formed to look after the clearance activities of the engines, and brought out the requirements for re-type tests similar to UK procedures.

In 1968, the CREs were brought under the functional and administrative control of DRDO, reporting to SA to RM, through the Director of Aeronautics. The CRIs remained under DTD&P (Air), reporting to the Secretary, Defence Production. During this period, the Marut (HF 24) design activities, started under the leadership of Prof Kurt Tank, reached its peak. However, in-depth interactions/involvement of CREs for the design clearance activities were lacking. After the crash of HF 24 aircraft with reheat version of modified engine, the active participation of CRE (Aircraft) was considered essential and ensured with the concept of involvement in all activities of design and development, leading to clearance of the aircraft for development flights on a flight-by-flight basis as a mandatory requirement. These requirements were subsequently extended to other

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projects like HJT 16, Ajeet, HPT 32, etc. These aircraft were certified for release to service for operational deployment by the CRE (Aircraft).

The experience of CREs in certifying a wide variety of aircraft and equipment were consolidated into a procedure document called Design Development and Production of Military Airborne Stores (DDPMAS –1975). The same was issued by the Ministry of Defence as a mandatory requirement to be followed by the certification authorities, quality assurance personnel, industry, users, and private companies. This document has since been reviewed, amended, and re-issued by the Ministry of Defence as DDPMAS – 2002.

Subsequently, under Directorate of Aeronautics, the officers of CREs were started at the HAL divisions at Foundry & Forge, Kanpur; Koraput; Korwa Helicopter; Hyderabad and Lucknow; at Base Repair Depot (BRD), Chandigarh; at Defence Research & Development Laboratory (DRDL), Hyderabad; and at Armament Research & Development Establishment (ARDE), Pune. These offices were called Resident Technical Office (RTO), with CRE as the head. RTO, Nasik was established in 1968, but started functioning in 1971.

DRDO felt the necessity to have a dedicated setup to look after the airworthiness functions, reporting to the Secretary, Defence Research. The Centre for Military Airworthiness and Certification (CEMILAC) was formed at Bengaluru in 1995, with the head of CEMILAC designated as Chief Executive. An advisory council was formulated with Secretary, Defence Research as its Chairman and members drawn from IAF, IN, Army, Aviation, PSU, DRDO, Director General, Civil Aviation (DGCA), academic institutions, and Directorate General Aeronautical Quality Assurance (DGAQA) to periodically review and provide guidelines for the effective functioning of CEMILAC. All CREs were brought under the technical and administrative control of the Chief Executive (CE), CEMILAC. The RTOs were named as Regional Centres for Military Airworthiness (RCMAs) with their heads designated as Regional Directors (RDs). The CE, CEMILAC reports to the Secretary, Defence Research, Ministry of Defence. The day-to-day activities on safety, certification, and interactions with HAL/Air Force/Navy/Army/DRDO laboratories/private companies are looked after by the respective RCMAs in their allocated areas of disciplines.

RESPONSIBILITIES OF CRES/RDS

During Prototype Development Phase

• Beresponsibleforensuringthatthefirmiscognisantwith,correctlyinterpretsand applies the technical requirements.

• Bring up to the attention of CEMILAC, Air/Naval/Army Headquarters/Ministry of Defence, cases where there is difference of opinion between

Introduction

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the contractor and the concerned CRE/RD regarding compliance of a particular requirement.

• Evaluatedesignfeaturesofallmilitaryprojectsatthecontractor'sworksandverify conformity to design requirements. The CRE/RD is also responsible to ensure compliance of design and test requirements required for technical clearance of the stores by CEMILAC.

• ApprovetheDevelopmentandQualificationTestSchedulesandspecify thetest and analysis requirements for clearance of airborne systems and stores.

• Witnessgroundtestswherenecessaryandverifyadequacyofloadingandtestconditions. Where these are inadequate, one shall advise the contractor for revision of testing to appropriate loading and test conditions.

• Analyseflightresultsandexamineadequacy.Additionaltestsshouldbecalledwhere necessary. Shall attend the debriefing meeting when necessary.

• SubmittechnicalappreciationreportstoHeadquarters,CEMILACperiodicallyon evaluation of design features, ground and flight tests carried out.

• Arrange to collect Type Records, including test reports on wind tunnel,structural, mechanical and system tests, bench test, proving trials and flight tests. One set of these shall be forwarded periodically to CEMILAC.

During Production Phase

• Be the Chairman for Local Type Test Committee, Local Concession Committee, and Lifing Committee.

• Examinetheacceptability,orotherwiseconcessions,referredtobyCRI,whenstrength, safety interchangeability, etc. are affected.

• Examinemodificationproposalsputupbythecontractorinrespectofprojectsunder his control, call for the tests required, technically accept the modification proposals, and act as the Chairman of the Local Modification Committee constituted for the various projects. In the discharge of this responsibility, one shall take all necessary actions to ensure acceptance of the modification by the user services prior to his formal technical clearance and prescription in the standard of preparation.

• Examineandapprovealldraft servicing instructions(SIs), special technicalintructions (STIs), urgent operating notices (UONs), urgent servicing notices (USNs), service bulletins (SBs), and Lifing Policies that are required to be issued for the maintenance of airworthiness standard of the aircraft manufactured at thecontractor'sworks.

• Defineperiodicallythedesignstandardsforproduction/overhaulofaircraft;examine and approve changes to ground and flight test schedules; examine cases of concessions put up by the contractor for non-compliance of modifications,

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SIs, STIs, UONs, USNs, Repair Schemes, etc., during manufacture; and overhaul of aircraft manufactured by the contractor.

• Maintainday-to-daycontactwithserviceheadquartersinrespectofaircraftin service use, on matters arising from technical and operating experience of such aircraft, and take action as considered necessary to ensure maintenance of airworthiness.

• Participate and ensure adequacy of investigation of defects and incidentscarried out by the contractor on design aspects.

• Examine tests carried out on components indigenously developed at thecontractor's works and forward, to CEMILAC, recommendation for typeapproval.

• Be satisfiedhimself on the adequacyofproduction, groundand flight testschedules, and approve the ground and flight test schedules and their amendments.

• Beresponsibletoapprovespecifications/drawingsofthematerial/componentsand lay down test requirements for approving the same in respect of items proposed by the contractor to indigenise or substitute, material or components from other countries.

• All defect investigations carried out during development phase shall havemember from RCMA.

STRUCTURE OF CEMILAC

The flow chart indicates the structure, organisation and interactional ambit of CEMILAC.

Directorate General of Aeronautical Quality Assurance

The Directorate General of Aeronautical Quality Assurance (DGAQA) is under the Department of Defence Production and Supplies in the Ministry of Defence. DGAQA is responsible for the quality assurance and acceptance of aircraft/aero-engines/helicopters and aeronautical stores manufactured/overhauled/repaired at various divisions of HAL, stores manufactured by ordnance factories and in private sector, besides other responsibilities.

The head of DGAQA is the Director General and its headquarter is located in New Delhi. It has branch offices located at the various divisions of HAL in a manner similar to RCMAs; the branch offices are termed ADGQAs. The responsibilities of DGAQA and ADGQAs are summarised below: • Exercise controlover thequality controlorganisationof a firmand report

to headquarters of any fall in the standard of the firm's quality assuranceorganisation/staff.

Introduction

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• Ensure,throughphysicalexamination,thatthefirm'squalityassurancestaffhave carried out comprehensive quality assurance at all stages, from raw materials stage to the final delivery of the product, and introduce such checks and procedures as considered necessary from time to time.

• Introducestagesofphysicalqualityassurancethatarecomprehensiveandcoverquality assurance, from the incoming raw material and stores to the finished product and final assembly stage. These are to be reviewed periodically for ensuring better supervision over the firm's quality assurance organisation.WhenevertheCRIs'stagesofqualityassurancehavebeencommunicatedtothefirm,thefirm'squalityassuranceresponsibilityshouldbepermitted.

• Ifthereisaneedtodeviate,itshouldonlybedoneinconsultationwithCRI.• Ensure that all deviations from the stipulated requirements are properly

authorised and recorded. Whenever there are deviations of a major nature affecting safety, strength, interchangeability or other operational aspects, these

Secretary Defence Research

Chairman : SA TO RMCo-Chairman : CAS NomineeMembers : INF. IN. Army Aviation, PSU, DRDO, DGCA, Academic Insts., DGAQA

Centre for Military Airworthiness and

Certification (CEMILAC)

CEMILAC Advisory Council

Analytical Inputs• HAL• Academic Institutions• Aero Labs• AR & DB

Propulsion Group• RCMA (E)• RCMA (KPT)• RCMA (M)• RCMA (C)• RCMA (GTRE)• RCMA (F&F)

Aircraft Group• RCMA (A/C)• RCMA (N)• RCMA (KD)• RCMA (H)

Avionics Group• RCMA (L)• RCMA (HYD)• RCMA (KW)• RCMA (AA)

ConsultancyIFAA : CAA PE UK

National Labs DRDO

Labs

Public Sectors

Support toAirworthiness

Assurance to User Services

• IAF• IN• Army Aviation

Private Sectors

Joint Civil Military

Certification

ADABRDS

Structure of CEMILAC

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shall be referred to CRE/RD for decision. Deviations affecting operational aspects shall be referred to Air/Naval/Army Headquarters/RD for decision.

• Report to Headquarters, details of new design projects or manufacturingmethods or processes that may affect the established inspection procedure, and raise critical observations thereon.

• AssistDGAQAHeadquartersinindigenoussubstitutionactivity.• During theprototypedevelopmentof stores and trial installation, associate

with all phases of development and testing of stores.• ReleaseaircraftfortestflightsbyissuingForm1090.

Interface between CEMILAC and DGAQA

The involvement of RCMA and CRI in various day-to-day activities during development, testing, production, overhaul, and indigenisation tasks like LTCC, LCC, LC, snag rectification, testing, etc., ensures a systemic interaction mechanism at all stages. However, the system does not always take care of individual personalities, which could cause stand-offs and sometimes confrontation on perceived overlapping of authority. The headquarters of CEMILAC and DGAQA would then have to step in and smooth out the issues.

ABOUT THIS MONOGRAPH

This monograph discusses the aspects concerning the methodology adopted for airworthiness certification in India for military aircraft, systems, hardware and software. The certification process through concurrent design evaluation and clearance to the next agreed stage are elaborated. The concepts of milestones in the project are addressed. The methodology adopted by the certification authority in evaluating the design from airworthiness and safety viewpoints throughout the design and development phase, for according clearance for development flight tests, is presented. Approach to confine clearing the aircraft for development flight tests, based upon extensive wind tunnel simulation and ground test evaluation is elaborated. Specific certification activities for various facets of aircraft design, development, production and life cycle management of the aircraft will be discussed covering the following aspects.• ProjectInitiationandDevelopment• OverviewofAirworthinessCertification• TechnologyDevelopment• Ab-initioDesign,Development,andProduction• TrialEvaluation• PrototypeDevelopmentandProduction• LicenceProgrammes

Introduction

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• IntroductiontoAircraftDesign• DesignEvaluationMethodologiesforCertification• BoughtoutAircraft• ContinuedAirworthiness• VarioustypesofModifications• Mid-lifeUpgrades• WeaponSystems• LifeEvaluationofAircraftandAirborneStores• LicenceManufacturedAircraftandAirborneStores• AircraftAccidents,IncidentsandDefectInvestigation• IndigenousDevelopment• COTSanditsCertificationImplications

Design implications of not following the concurrent clearance approach are discussed through a brief overview of the design aspect. Pros and cons of delegation of airworthiness function to the contracting firm through approved designers and airworthiness groups within the firm will also be discussed. The tools adopted for design evaluation like failure analysis, failure tolerance criteria, reliability analysis, risk analysis, etc., are discussed to demonstrate how, at the end of this process, the user gets an assurance that aircraft is safe to operate within the stipulated limits and the build standard of the certified aircraft provides the extent of performance level desired in the requirements spelt out by the service headquarters in appropriate Air Staff Requirements (ASR)/Naval Staff Requirements (NSR)/General Staff Quality Requirements (GSQR).

The document is structured in such a fashion, that chapters one through five will provide information that is extent sufficient in scope and depth to be of interest to the individuals desirous of understanding the basic concepts of airworthiness certification. Chapters six through twenty five provide information in greater detail to be of utilitarian interest to a practitioner of the discipline of airworthiness certification.

A brief explanation of the terminology used and institutions named in the document is given in pages xvii to xx and the evolution of Airworthiness Certification is covered in Introduction from pages xxix to xxxv.

CHAPTER 1

Technology Development

Technology development can be a precursor to enable the government to commit to a particular programme. A contractor provides evidence that the technology being proposed is viable, and that he has the expertise and capability to undertake the programme. This demonstration enables the government to take a decision on project sanction. Thus, technology demonstrator programmes are an extremely important route for decision-making. If unexpected technical or operational problems are uncovered after this point, the effort, time and cost to correct them can be significant, with impact on the time and cost schedules. Hence, the technology demonstrator phase should thoroughly evaluate the technologies and operational concepts, using actual hardware and software, so as to bring out potential problems and take corrective actions. It is worthwhile to note in this context, the experience of USAF in the F111 and C5A programmes of the 1960s. These had followed the ‘total system’ acquisition concept of the then Defence Secretary Robert McNamara, which did not require technology demonstrators and hardware test demonstration, relying instead on analyses and simulation as the basis for decision-making. This resulted in performances shortfalls, cost overruns, and schedule delays.

Due to the very nature of a programme conceptualised to be a platform involving cutting edge technologies, CEMILAC/RCMAs will not have the advantage of availability of the technical specifications and standards to evaluate the design for safety, and performance, and to provide statements of compliance. The most recent example is the demonstration of the control configured vehicle (CCV), glass cockpit and composite technologies.

In such a technology demonstrator programme of critical importance to decision-making, the role of CEMILAC/RCMA will at best be limited to ensuring that safety-of-flight is ensured, by a thorough assessment of safety aspects. This will be necessary since such aircraft will also have to be flown by the service

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pilots. CEMILAC/RCMAs should provide a statement on the performance achieved to enable decision-making by the government.

The question arises as to how safety assessment can be done without a sound knowledge of the technologies involved, to assess the limits within which it is safe to operate and to determine the boundary conditions for operation, ensuring that adequate margins are provided for excursions. The only approach is a painstaking one–by means of a sound knowledge of the basic aspects of aircraft design, and extensive literature survey with particular reference to (1) National Technical Information Services (NTIS), (2) National Aeronautics and Space Administration (NASA) and (3) Socity of Automotive Engineers (SAE) reports as well as proceedings of NFTE, NFTP, and IEEE seminars. These cover the current technologies. A systematic compilation of a good database, in respect of analytical as well as experimental work done in various organisations, will serve as the baseline knowledge. Keeping the above points in view, the design aspects have been provided a good coverage in chapters – 5 through 21, which would be particularly helpful to the younger entrants into the certification discipline.

The next step is to make use of the interactive sessions with the various contracting firms in the form of technical meetings. It will be helpful if a detailed questionnaire is prepared and answers obtained. An example is the case regarding the queries on low temperature operation of the flight control actuator. The discussion with the scientist at Wright Laboratories, USA, who in fact had drafted the specification, brought out that fluid temperature gets hot due to the high frequency of operation of flight control actuators on statically unstable aircraft, and that in fact high temperature operation is more critical than low temperature operation for this class of aircraft.

The safety considerations should be based on input/output criteria and definition of the number of failures a system should tolerate. Whatever the technology level being dealt with, the safety criteria cannot be of a level lower than that with a conventional system.

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Airworthiness certification Short