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Foreword
The Department of Aerospace Engineering at the Indian Institute of Science in Bangalore is
hosting a 3 - day seminar like series of lectures on Aging Aircraft in its department premises on
27 - 29 November 2019. The program consists of about 20 presentations on various technical
aspects surrounding the subject by a distinguished panel of national and international lecturers.
The subject is also of interest to the Indian National Academy of Engineering (INAE) in view of
its criticality to both strategic and civil aviation sectors and the advanced engineering &
technologies involved. Partial financial support is provided by the Indo-US Science and
Technology Forum (IUSSTF), Indian National Academy of Engineering, CSIR-NAL, and Office
of Naval Research - Global, Singapore.
The proposed lecture series is designed to provide regulatory personnel, fleet operators,
managers, military commanders, designers and industry personnel responsible for upgrading the
capabilities and safety of their fleets, maintenance personnel at air logistics centers and depots,
and specialists involved with aircraft design, insight into issues involved in ageing aircraft and
their impact on safety and economic burden due to higher cost of maintenance, repair and
replacement. It will help them in making tactical adjustments to better manage their aging fleets
in terms of capacity and maintenance costs, and in the case of military aircraft their operational
readiness in a changing environment also.
The term Aging Aircraft suddenly entered our lexicon in 1988 when a commercial jet aircraft
operating in the United States suffered an in-flight structural failure. Though a major catastrophe
was averted and almost everyone on board survived, the ill-fated aircraft’s structural integrity
was found to be severely degraded due to fatigue and corrosion. The aircraft was operating well
beyond its manufacturer-suggested economic life of 20 years, like many aircraft in present day
service are. However, it must be emphasized that current regulations offer adequate protection to
ensure that even if an aircraft has reached or exceeded superannuation it would be airworthy but
only if structural degradation like what was found in the ill-fated aircraft is absent. Post failure
examination of the subject aircraft and subsequent analyses that were conducted revealed that
60% of the jet transport commercial fleet worldwide was at risk due to the same kind of failure.
Almost simultaneously, the United States Air Force (USAF) came across a disturbing pattern of
structural degradation occurring in one of their older models, which concern was exacerbated a
short time later by concerns about the safety and integrity of other critical subsystems.
Although there are several other reasons for developing awareness among the community in
India about the challenges involved in operating aging aircraft, the unacceptably high threat that
could be posed to the nation’s transportation infrastructure by aging aircraft is sufficient
motivation for conducting the lecture series.
The organizers would also like to thank IMechE, UK, Indian Structural Integrity Society,
DGCA, DRDO, and HAL for extending support to this lecture series.
Organized by
Sponsored by
INDIA-USA LECTURE SERIES ON AGING AIRCRAFT
(IULSAA)
Venue: Satish Dhawan Auditorium, IISc, Bengaluru, India
TECHNICAL PROGRAM
November 27, 2019
08.00 am - 09.00 am Registration
09.00 am - 09.50 am Inaugural Session
Plenary -Session
Chair: Dr Kota Harinarayana
09.50 am - 10.20 am First Plenary Talk
Sustenance of Aircraft Fleet Through Aging Management
Air Marshal Vibhas Pande VSM, Indian Air Force, India
10.20 am - 10.50 am Second Plenary Talk
Building an Environmental History for US Naval Aircraft
William Nickerson, Office of Naval Research Global, Japan
10.50 am - 11.20 am Coffee/Tea Break
Session I
Chair: Cmde C D Balaji
11.20 am - 12.20 pm Aging Aircraft: An Introduction
Dr S G Sampath, FAA, USA - Retired
12.20 pm - 01.20 pm Airframe and Aeroengine Fatigue under Extended Service
Usage
Dr R Sunder, Bangalore Integrated System Solutions, India
01.20 pm - 02.00 pm Lunch
Session II A
Chair: Mr. Ashok Baweja
02.00 pm - 03.00 pm NDE and SHM for Aerospace Applications
Dr Krishnan Balasubramaniam , IIT Madras
03.00 pm - 04.00 pm Aging Aircraft Engines
Dr Prakash Patnaik, National Research Council, Canada
04.00 pm - 04.15 pm Coffee/Tea Break
Session II B
Chair: Mr. Ashok Baweja
04.15 pm - 05.15 pm Overview of Helicopter Fatigue
Mr. Ugo Mariani, Leonardo Helicopters, Italy
06.00 pm - 08.00 pm Cultural Program-An Evening of Carnatic Music
Carnatic Music Concert by Prof. Sankaran Mahadevan,
Vanderbilt University
08.15 pm onwards Dinner at IISc Guest House Lawns
November 28, 2019
Session III A
Chair: Dr S K Chaudhuri
09.00 am - 10.15 am Human Factors in Aircraft Maintenance and Inspection
Prof. Colin Drury, University at Buffalo, SUNY, USA
10.15 am - 11.15 am Review and Assessment of Airframe Repair Schemes
Dr Jayanth Kudva, NextGen Aeronautics, USA
11.15 am - 11.30 am Coffee/Tea Break
Session III B
Chair: Dr S K Chaudhuri
11.30 am - 12.30 pm Monitoring Aircraft Load Spectrum Towards an Integrated
Structural Health Management
Prof. Afzal Suleman, University of Victoria, Canada
12.30 pm - 01.30 pm Lunch
Session IV
Chair: Dr K Ramchand
01.30 pm - 02.30 pm Electromagnetic NDE Activities at MSU on Aging Aircraft
NDE
Prof. Lalita Udpa, Michigan State University, USA
02.30 pm - 03.30 pm Digital Twin Technology for Aircraft Health and Operations
Management under Uncertainty
Prof. Sankaran Mahadevan, Vanderbilt University, USA
03.30 pm - 04.00 pm Coffee/Tea Break
Session V
Chair: Prof. B Dattaguru
04.00 pm - 05.00 pm Effect of Newly Promulgated, Environmental Rules
Dr Prakash Patnaik, National Research Council, Canada
05.00 am - 06.00 pm Technology Insertion into a Combat Aircraft: Opportunities
and Challenges
Dr K Vijayaraju, Aeronautical Development Agency (DRDO)
07.30pm onwards Banquet Dinner at Kirloskar Hut, Bangalore Golf Club
November 29, 2019
Session VI
Chair: Mr. Vijay Raman
09.00 am - 10.00 am An Overview of Corrosion Monitoring for Aircraft –
Problems and Prospects
Dr Prakash Mangalgiri, Visiting Professor, IIT Kanpur, India
10.00 am - 11.00 am Aging Avionics
Shri Yogesh Kumar, HAL, India - Retired
11.00 am - 11.30 am Coffee/Tea Break
Session VII A
Chair: Prof. R Ganguli
11.30 am - 12.30 pm Aging of Aircraft Electrical Wiring
H R Sudarashan Prasad, Centre of Excellence in Aerospace and
Defence, India
12.30 pm - 01.30 pm Structural Life Management in a Combat Aircraft
Dr Mangalgiri, Visiting Prof, IIT, Kanpur, India and Dr A R
Upadhya, Former Director, CSIR-NAL, India
01.30 pm - 02.30 pm Lunch
Session VII B
Chair: Prof. R Ganguli
02.30 pm - 03.00 pm Regulatory Aspect of Ageing Civil Aircraft
Dr Ramakant Singh, DGCA, India
03.00 pm - 03.30 pm Presentation from Private Airlines
03.30 pm - 04.00 pm Coffee/Tea Break
04.00 pm - 04.30 pm Feedback Session
Speakers’ Profiles & Abstracts
Air Marshal Vibhas Pande VSM, Indian Air Force, India
Air Marshal Vibhas Pande VSM assumed the present appointment of DG (Aircraft) on 01
February 19. Air Officer was commissioned as Aeronautical Engineer (Mechanical) in IAF on 29
August 1984. He started his career as Engineering Officer in IAF with MiG-23 BN aircraft and
later also gained experience in maintenance operations on An-32 and Mi-17 helicopter. As a
Flight Engineer, he has flown Mi-8 & Mi-17 helicopter and has been Air Force Examiner for
Rotary Wing aircraft.
Air Officer is a Post Graduate in Reliability Engineering from IIT Powai, Mumbai and is
alumnus of College of Air Warfare and National Defence College.
He has held the appointments of Senior Production Engineer at 11 Base Repair Depot,
Commanding Officer of Air Armament Inspection Wing Khamaria, Directing Staff at College of
Air Warfare and Command Engineering Officer at HQ WAC. He has been founder CO of 1
CIMD, commanded 11 Base Repair Depot and was Senior Maintenance Staff Officer at HQ
EAC. Prior to assuming his current appointment, he served as ACAS Eng (T&H).
He is an avid sportsman and enjoys playing Squash and Golf. He is married to Mrs. Ruchira
Pande and blessed with two daughters.
Sustenance of Aircraft Fleet through Aging Management
Air Marshal Vibhas Pande VSM
DG (Aircraft),
Indian Air Force
Mr. William Nickerson, Office of Naval Research Global, Japan
William Nickerson is a Science Director for Office of Naval Research Global (ONRG) based in
Tokyo. ONRG is comprised of scientists and engineers that apply Science and Technology
(S&T) to improve the capabilities of the Navy and Marine Corps by establishing mutually
beneficial relationships with S&T partners around the world. Mr. Nickerson has 23 years of
experience within the DoD, serving as both a program officer and primary investigator for
multiple programs within the DoD science, engineering and logistics functions. Mr. Nickerson
has provided S&T, Acquisition, RDT&E, and In-service Engineering support to Naval Aviation
and the Joint Service community throughout his career. In his ONR role, he is working to
enhance research efforts for next generation air vehicle structures and materials. His research
areas of interest include combined loading mechanics and service life prediction, materials
selection and durable aircraft design, 3D capable advanced composite structures, and advanced
protection, inspection and repair of airframe structures.
Building an Environmental History for US Naval Aircraft
William Nickerson
Science Director
Office of Naval Research Global, Tokyo
Email: [email protected]
Abstract
The operating environment of US Navy aircraft varies significantly depending on the geographic
location, flight operations, and surrounding activities. All of these various conditions promote
environmental degradation that impacts the structural life and capability of the airframe and
components. Aircraft loading conditions will also influence the type and degree of
environmental damage. Building an environmental history that can monitor and track
environmental service life similarly to how we monitor and track mechanical service life is
crucial. Such a history will allow the corrosion to be treated as a structural factor, and allow for
time variation of environmental factors instead of using inaccurate proxy data such as average
geographic environment.
Dr S G Sampath, FAA, USA (Retired)
Dr. S. G. Sampath, “Sam,” retired in May 2010 from the U.S. Army’s Research, Development
and Engineering Command. Prior to his tenure at RDECOM he successively served as the Chief
of the Aeronautics and Mechanics Branch at the International Technology Center (ITC) in
London during 1998-2006 years, and as the Engineering Director of ITC-Pacific during 2006-
2008. In the 10-prior years he was employed by the Federal Aviation Administration (FAA)
where the served as the Manager of the National Aging Aircraft Research Program, which had to
deal with issues of import in the context of the nation’s infrastructure. He also served on the
Science and Technology Panel of the Joint Aeronautical Commanders Group (JACG).
Prior to his employment with the FAA, he was in the Research and Special Projects
Administration, another agency within the U.S. Department of Transportation, involved mainly
in crashworthiness and survivability research. Between 1986 and 1989, he was employed by the
Defense Systems Division of Goodyear Aerospace Corporation, later acquired by Loral
Corporation. Dr. Sampath was employed by the Battelle organization for about 13 years, first at
their Columbus Division, then at their research center in Geneva, where he was in-charge of
several inter-disciplinary projects.
Since retirement from the U.S. Army, he operates a small company, offering consultation
services on Science and Technology matters. His involvements since retirement relate to a
variety of projects such as sentient systems, energy saving through formation flight by micro-
aerial vehicles, graphene, surface treatment methods, and mitigation of the effects of blast loads.
Most recently he is attempting to convene a specialized workshop on Cognitive Abilities of
Elephants, which can then be incorporated in sentient systems.
He has a Master’s degree in Physics, a research degree in Aerospace Engineering from the Indian
Institute of Science, and a Ph.D. degree in Engineering Mechanics from the Ohio State
University. He served for several years on the Structures and Materials Panel of NATO’s
Advisory Group on Aerospace Research and Development (AGARD) and chaired the Group on
Durability and Damage Tolerance. He was also active in the AGARD’s successor organization,
the Research and Technology Organization (RTO) during which he was engaged in several
technical activities and special assignments by the two organizations. He was a member of the
Damage Tolerance Committee of the American Helicopter Society, and the Design and Analysis
Committee of the Pressure Vessel and Piping Division of ASME. He is a member of Sigma Xi
Scientific Society. He received the Distinguished Alumnus Award from the Aeronautical
Engineering Department of the Indian Institute of Science during their Golden Jubilee
Celebration in 1993.
Aging Aircraft: An Introduction
Dr S G Sampath
FAA, USA (Retired)
Abstract
This brief presentation begins with a genesis of how the term, Aging Aircraft, entered into our
collective consciousness and lexicon. It then mentions legislation passed shortly thereafter by
the U.S. Congress, which was subscribed to by all the stakeholders, worldwide. The legislation
enabled the Federal Aviation Administration (FAA) to formally initiate their National Aging
Aircraft Research Program, under whose auspices research inquiry into the causes of Multiple-
Site Damage (later termed as Widespread Fatigue Damage) was undertaken, as were strategies
for its prevention. Initially, research and development was also directed towards developing
more effective corrosion prevention products and methods to arrest corrosion, expansion of the
range of available Non-Destructive Inspection (NDI) technologies for flaw and corrosion
detection in airframe and engine components, ways to improve Inspection Reliability, and
development of aids to assist the FAA’s corps of Aviation Inspectors manage their certificate
holders. As concerns due to other reasons surfaced, partly due to various other highly publicized
accidents, like the catastrophic one that overtook the MD-11 in 1998 over Grand Banks due to
faulty wiring, the research agenda saw a concomitant expansion. Starting in 1993, the U.S. Air
Force also started experiencing aging related problems in some models of their aircraft, which
escalated in extent as well as their response.
It became quickly clear Aging Aircraft had several connotations: technological obsolescence,
need for system or subsystem upgradement, such as avionics suite, changing mission
requirements that were unanticipated during the design stage, runaway costs if a properly
conceived maintenance program is not instituted, perceived or otherwise reduction in safety
levels, impairment of fleet readiness, unavailability of replacement parts due to shutdowns of
manufacturing lines or business enterprises, operations distant from home depot facilities – all
leading to unbudgeted expenses.
The presentation then goes into certain facets of research, which was ill-conceived due to
insufficient deliberation and diligence.
The purpose behind this and other presentations to follow is three-fold: (a) adherence to a well
thought maintenance program will allow the aircraft to age gracefully, and result in higher
operational readiness and lower cost-of-ownership, (b) undue haste in undertaking research
without a well thought through plan can result in wasteful expenditures, and (c) an aging aircraft
program should be instituted early, preferably during the design stages, where factors such as
inspectability, easy maintenance, architecture that favours modularity, and ease of inserting
newer technology are considered.
Dr R Sunder, BISS, India
Curriculum Vitae of Dr. Ramasubbu Sunder
Research Director, BISS Division
ITW-India (P) Ltd
MTech, PhD in Aeronautical Engineering (1978) Kiev Institute of Civil Aviation.
Research in aeronautical fatigue and airframe residual strength at the National Aerospace
Laboratories, Bangalore, India (1978-1993).
Research on Elevated temperature fatigue crack growth in nickel-base superalloys at Air Force
Materials Laboratory, Wright-Patterson Air Force Base, Ohio (1986-88 and as consulting
scientist on Ageing Aircraft Programmes at UDRI, 1990-2001).
Founder, Bangalore Integrated System Solutions (P) Ltd (BISS) in 1992, a developer and
manufacturer of mechanical test systems. BISS is presently an independent business unit of
Illinois Tool Works (ITW), USA.
1992 – to date: Test technology development for wide range of applications. Research on metal
fatigue under service loading.
Member, ASTM (from 1985) and ASTM Committee E-8 (Fatigue & Fracture) & D30
(Composites).
Fellow, Indian Academy of Sciences
President, Indian Structural Integrity Society
About 70 peer reviewed publications.
Airframe and Aeroengine Fatigue under Extended Service Usage
R Sunder
BISS Division, ITW-India, Bangalore, India
Abstract
The common thread running through aging airframe structures is the invariable extension of their
usage beyond what may have been envisaged by their original design, this particularly so when
viewed in terms of calendar years of service. Just as in the case of human life itself, with age
comes the increasing competition of multiple degradation mechanisms.
The focus of this lecture is on fatigue thresholds and how they may be affected by extended
service usage conditions in a manner that affects the early stages of fatigue crack growth. Twenty
years ago, collaborative research with the US Air Force Research Laboratories resulted in the
discovery that the mean stress and residual stress effects in metal fatigue are an environmental
phenomenon. This was proven through reproducible experiments in high vacuum.
Follow-up research at BISS Labs, Bangalore over the past twenty years served as the foundation
for a radical transformation of our understanding of fatigue thresholds and of near-threshold
fatigue crack growth that effectively determine material and structural durability.
We now know for example, that intrinsic threshold stress intensity, Kth for a material is uniquely
related to a certain computable near-tip residual stress. This is so in atmospheric fatigue because
of the manner in which crack-tip diffusion kinetics may be related to instantaneous local stress at
the commencement of a fatigue load cycle. Modeling fatigue crack growth using the new
understanding to estimate residual fatigue crack growth life under a transport airframe load
spectrum appears to show results of promise.
A historical perspective is presented of the two decades of research that led to the development
of a new testing practice as well as its engineering application to vastly improve the ability to
model residual fatigue life of structural elements seeing extended usage in the HCF/VHCF
regime.
Prof. Krishnan Balasubramaniam, Indian Institute of Technology Madras, India
Prof. Krishnan Balasubramanian is currently the Dean for Industrial Consultancy and Sponsored
Research at the Indian Institute of Technology Madras. He also serves as a Chair Professor in the
Department of Mechanical Engineering, and also serves as the Head of the Centre for
Nondestructive Evaluation which he founded in 2001. His research focus is in the field of Non-
destructive evaluation, Smart Inspection and Structural Health Monitoring, with applications in
the fields of maintenance, quality assurance, manufacturing and design.
He received his undergraduate degree in Mechanical Engineering from the University of Madras
(Regional Engineering College, Tiruchirapalli, India) in 1984. He then graduated from Drexel
University with a M.S. degree in 1986 and a Ph.D. in the year 1989. Before joining IIT Madras
in 2000, he was employed at Mississippi State University. He has over 450 technical
publications (including 220 refereed journal papers), 18 patents filings and has directed 24 PhD
student dissertations and 48 MS student theses.
In recognition for his outstanding contributions to research in the field of Nondestructive
Evaluation, he was conferred with the ROY SHARPE PRIZE by the British Institute for NDT for
the year 2012. He was also awarded the ISTEM Entrepreneurial Faculty Member Award for his
entrepreneurial activities by Auburn University, USA in 2011 and the NATIONAL NDT
AWARD 2010 by the Indian Society for NDT. He was conferred with the DRDO Academic
Excellence Award for the year 2015. He has served as a Board Member of the World Federation
of NDE Centers (WFNDEC– www.wfndec.org) that is headquartered in Iowa State University,
USA. In 2018, he was bestowed with the prestigious ABDUL KALAM National Technology
Innovation Fellowship by the Indian National Academy of Engineers and the Life Time
Achievement Award by the Indian Institute of Technology Madras. He has been instrumental in
the incubation of several startups including Dhvani Research, Playns Technologies, Detect
Technologies, Trotix Robotics, HyperVerge, Maximl Labs and Solinas Integrity, and has jointly
developed several new products through these companies. He currently serves as the Editor-in-
Chief of the Journal for Nondestructive Evaluation (ISNT) and as the South-east Asia Editor for
the Journal of Nondestructive Testing and Evaluation (Taylor and Francis). He also serves as the
Associate Editor of Ultrasonics (Elsevier) and Subject Editor of NDT International (Elsevier)
and also serves in the editorial board of the Journal of Structural Longevity (Techscience). He
also is a board member of the World Federation of NDE Centers and the QNDE Scientific
Advisor Committee.
He is a Life Fellow of the Academia NDT International, Life Fellow of the Indian Society of
Nondestructive Testing (ISNT) and a Fellow of the Indian National Academy of Engineers.
NDE and SHM for Aerospace Applications
Prof. Krishnan Balasubramaniam
Chair Professor in Mechanical Engineering
Head of Centre for Nondestructive Evaluation (CNDE)
Indian Institute of Technology Madras, Chennai, 600036 INDIA
Email: [email protected]
Abstract
NDT methods are currently employed in the quality assurance during the manufacturing and for
in-service inspection of aerospace components and structures. Most of these techniques are
focused on the detection, sizing, and characterisation of flaws such as cracks, at pre-determined
critical locations, that lead to fractures and hence failures in the component. Advanced NDE
methods are being developed by the Centre for NDE at the Indian Institute of Technology
Madras (CNDE@IITM) that may potentially influence the fabrication, inspection, safety,
costing, and maintainability of the aerospace components and its fleets in the military as well as
the commercial sector. Some of the techniques that will be discussed here includes: (a) Use of
ultrasonic guided waves for the improved inspection of complex structures and components
including hidden areas, (b) Structural health monitoring of components and structures using
attached and embedded sensor networks, (c) Use of new and novel active thermography
techniques for thermal barrier coatings on engine components, and (d) Waveguide sensors for
process condition measurements. Using the methods discussed here, the operator now has the
opportunity to take vital decisions such as component integrity and propose necessary
repair/replacement or estimate the remaining life of the component.
Dr Prakash Patnaik, National Research Council, Canada
Dr. Patnaik received his B. Engg.(Hons) degree in India followed by a Masters and Ph.D. in
Materials Science & Engineering from McMaster University in Canada in and had an impressive
start to his career as a NSERC Visiting Fellow Research Scientist to the NRC’s National
Aeronautical Establishment in 1984. He worked for internationally recognized defence
companies such as Hawker Siddeley Canada and the Magellan Aerospace Corporation as a
Senior Engineering/R&D Manager (1986-2001) prior to moving to NRC in 2002. In 2012, he
was appointed as the Leader of NRC’s Air Defence Systems Program (ADS) and working with
DND, the RCAF and DRDC generated nearly $60M revenue (till the end of FY18) in the
program and delivered research and technology outcomes in line with the ADS Program’s value
proposition. Dr. Patnaik’s research engagement and contributions to private and public sector in
Canada has led him to receive numerous recognitions and awards of which the ASM Fellow,
Research Fellow Pratt Whitney Canada and Fellow of the Canadian Academy of Engineering are
worthwhile to note.
Dr. Patnaik is a member of many international scientific organizations and committees and has
earned many awards and recognitions in between 1978 till 2018. He is a member of the NATO
Science and Technology Organization (STO) and a former Chair of the NATO-STO Technical
Committee on Mechanical Systems and Materials for the Applied Vehicle Technology panel and
recently elected to be the Vice-Chair of the NATO-AVT S&T Strategic Committee. In
December 2018, he received the NATO-AVT Panel Excellence Award for his outstanding
contributions to the NATO S&T program of work in the Applied Vehicle Technology Panel and
more recently (Sept 2019) the NATO-STO Scientific Achievement Award (SAA) for his
contributions to the S&T.
He has recently been appointed by the Department of National Defence –DRDC as the Technical
Advisor in Defence Materials & Defence Aerospace (Five Eyes TTCP Defence S&T
Collaboration) as well. He also serves in the USAF-DND-DRDC Air Senior National
Representative (ASNR) Board as a technical advisor from NRC. On the academic side, he has
been adjunct professors at UBC, Carleton University and a Professor of Eminence at the Jain
University in India. He has completed serving the UBC advisory board in Materials Engineering
and currently serving in the industrial advisory board of the Carleton University Mechanical &
Aero as well as an advisory board member of the Defence & Security Science at McMaster
University in Canada. As a Fellow of the American Society for Materials (ASM) International in
the USA, he was selected to give topical lectures in India & Canada in early 2000 to promote
research collaboration between these three nations. A number of these appointments have been
NRC First and/or Canada First.
Aging Aircraft Engines
Prakash C Patnaik
Structures, Materials and Performance Laboratory, Aerospace Research Centre,
National Research Council Canada, Ottawa, Canada
Abstract
Nations around the globe are being faced with the need to operate fleets of mature gas turbine
engines built many years ago. Due to diminishing resources, replacing these engines with new
ones challenges are being faced. How long such engines can be still used in service safely,
without replacing a significant portion of their aged structural components have become a
growing concern to the engine life-cycle managers. Also, there are technical uncertainties in
residual lives of components that make it difficult for logistics in sustainment. Another concern
is the high maintenance cost associated with the replacement of critical components, such as
blades, vanes and rotors (disks and blisks). The need to balance the risk and escalating
maintenance costs explains the growing interest in the application of life extension technologies
for safely extracting maximum usage out of life-limited parts. In the case of aero-engines,
maintaining airworthiness while ensuring affordability is of prime concern to both life-cycle
managers and regulatory authorities.
This lecture describes the modes of deterioration of engine components leading to potential
failures and discusses their effects on the performance, operating costs, reliability and
operational safety of engines. It also identifies component life extension strategies that engine
life-cycle managers may adopt early to cost-effectively manage their engines, while ensuring
reliability and safety. Finally, advanced technologies such as additive manufacturing and the
digital twin approaches that can be reliably used for engine components, life management repair,
design and development are briefly reviewed.
Mr. Ugo Mariani, Leonardo Helicopter Division, Italy
After 5 years degree on Aeronautical Engineering at Politecnico di Milano, in Italy, I have been
working in Fatigue Department at AgustaWestland, now Leonardo Helicopter Division, and
CVE for Fatigue within Leonardo Helicopter DOA for more than 25 years.
On 1999 I was nominated Head of Fatigue Department and in this role I have been managing
fatigue and damage tolerance up to now.
From 1999 to 2002 I was nominated Co-Chairman of ARAC Working Group for Damage
Tolerance for Metallic Structures on Rotorcraft, committed to evaluate Industry White Paper and
TOGAA recommendations on rotorcraft fatigue and damage tolerance and propose appropriate
changes to FAR/JAR 29.571 and the related AC.
During this time substantial improvements were carried out to fatigue and damage tolerance
methodology applied to helicopter rotor and transmission parts and applied to the certification of
new civil helicopters AW139, AW189 and AW169, and also military variants EH101/AW101
and NH90. Moreover, they were systematically applied to the issues of continued airworthiness
of the fleet, supporting also special usage of aircrafts for both civil and military customers.
Fatigue and fracture mechanics data base and analytical tools had relevant development with
important role in changing our methods to manage fatigue life and fracture. The most relevant
topics of application are:
• Fracture mechanics applied to rotorcraft, with high frequency fatigue loading
• Small crack propagation and interface with NASGRO crack growth
• Defect tolerant methods based on Kitagawa approach
• Improve fatigue methods for composite materials and their damage tolerance, addressing
impact damage, manufacturing defects and environmental ageing
• Research on fracture mechanics for delamination of composite materials
• Health and Usage Monitoring of helicopters to improve fatigue life prediction and
damage detection
• Damage tolerance for transmission gears
Several papers were published on these subjects at International Committee on Aeronautical
Fatigue (ICAF), European Rotorcraft Forum (ERF) and AGARD / RTO.
Overview of Helicopter Fatigue
Ugo Mariani
Fleets Events within Safety System Governance
Former Head of Fatigue Department
Leonardo Helicopter Division
Abstract
The views presented in this paper are those of the author and should not be construed as
representing LHD position on the subject.
The loading of helicopter components is typically made by combinations of low and high
frequency loading conditions and changes also according to the aircraft usage. This very
demanding fatigue loading environment shortly outlined makes the fatigue evaluation of
rotorcrafts a peculiar discipline.
The detailed fatigue evaluation is carried out for all structural components whose failure could
result in a catastrophic event. Several methods are available and were accepted by the
Airworthiness Authorities.
Fatigue strength can be established by analysis or tests. Higher safety factors are applied for
analysis only, to cope with uncertainties in material fatigue strength, stress analysis and
manufacturing. For this reason, several fatigue tests are usually carried out. The fatigue
substantiation approach required by the rules up to the ’80 was related to pristine components,
without the deviations that may occur due to accidental damage, manufacturing discrepancies or
service environment. This safe life methodology for helicopters is an engineering approach that
each applicant has adjusted according to experience and legacy data within a comprehensive
method that was proved adequate and reliable by service history.
A deep discussion took place during the ’80 on the need to have damage tolerance requirement
also for helicopter fatigue, considering the effects of flaws and accidental damages and to
manage fatigue life by inspections, as a fraction of the time necessary to grow a fatigue crack to
its critical size for residual strength.
Under impulse of FAA the Regulatory Change to FAR 29.571 was approved in 1989 (Amdt. 29-
28), requiring tolerance to flaws and damages and opening the way to the application to
rotorcraft of the Damage Tolerance design philosophy.
Three options were basically offered by the new Rule and the paper shortly reviews the
differences.
More recently a further improvement of the rule required both retirements lives and inspection
intervals, to prevent generalized fatigue degradation due to helicopter usage and ageing in
normal conditions, and to prevent fatigue failures starting from accidental damages within a
realistic scenario of events.
Reporting from service and new technologies suggest further areas of improvements that are
summarized.
Prof. Colin G Drury, University at Buffalo, USA
Colin G Drury is SUNY Distinguished Professor Emeritus of Industrial and Systems Engineering
at University at Buffalo: SUNY. He is also President of Applied Ergonomics Group Inc., which
specializes in human/system integration for a variety of industries. These include Boeing
Commercial Aircraft, the US Postal Service, NASA (Space Shuttle), Delta Airlines, China
Airlines, General Electric and Sandia National Laboratories. His work has concentrated on the
application of human factors techniques for error reduction to manufacturing, quality and
maintenance processes. At UB, he was the Founding Executive Director of The Center for
Industrial Effectiveness (TCIE), which worked successfully to create and maintain jobs in the
Western New York region. Since 1989 he led a team to reduce errors in aviation maintenance
and inspection, as well as security services, as Director of Research Institute for Safety and
Security in Transportation (RISST). He has over 200 publications on topics in industrial process
control, quality control, aviation maintenance, security and safety. He is a Fellow of the
Institute of Industrial Engineers, the Chartered Institute for Ergonomics and Human Factors, the
International Ergonomics Association and the Human Factors & Ergonomics Society. Colin
Drury received the Bartlett medal of the Ergonomics Society and both the Fitts and Lauer
Awards of the Human Factors Ergonomics Society. In 2005 he received that FAA’s Excellence
in Aviation Research award, while in 2006 he was awarded American Association of
Engineering Societies’ Kenneth Andrew Roe Award. He is also a private pilot with extensive
experience in aviation matters.
Human Factors in Aircraft Maintenance and Inspection
Colin G Drury
SUNY Distinguished Professor Emeritus
University at Buffalo: SUNY
Abstract
Humans have always played a key role in the inspection, maintenance and operation of aircraft:
increasing reliance on electronics and automation is changing this role but not decreasing its
importance. Although most studies of accidents concentrate on the aircrew and operations,
maintenance contributes to around 15% of all accidents. Since at least 1989, human factors
engineering has contributed to better understanding of both the active and latent system failures
that lead to human error, and to the reduction or elimination of such errors. The chief principle is
to design out human errors by system interventions before attempting to modify human behavior
by selection or training. This presentation shows how the design and execution of the
maintenance system influences the error rate, and provides proven good practices for error
reduction. Specific issues in maintenance error are covered, including outsourcing of
maintenance, language errors, design of less error-prone documentation and how to help ensure
that maintenance procedures are actually followed. In the specific field of inspection,
quantitative models of how human inspectors perform a variety of NDI tasks are used to derive
good practices applicable to reduction of error in inspection. This in turn leads to improved
overall inspection reliability, which can reduce the potential for structural failure and lead to
more appropriate intervals for scheduled inspection.
Dr. Jayanth N Kudva, NextGen Aeronautics Inc. Torrance, USA
Education: IIT Madras, B. Tech, Aeronautical Engineering, 1973; Virginia Tech, PhD Aerospace
and Ocean Engineering, 1979; Certificate in AI, UCLA, 1989; Executive Management Program,
UCLA, 1998.
Dr. Kudva has 30+ years of experience in functional and technical management. He has been
PM/PI on over 50 R&D programs in diverse fields including UAVs, underwater vehicles, smart
materials, and human movement monitoring. During a 20-year career at Northrop Grumman
Corporation, he managed a Structures R&D group, spearheading company activities in smart
structures. He founded NextGen in 2003 to focus on transformative technologies for military
and commercial applications, with a five-year program from the US Defense Advanced Research
Projects (DARPA) on Morphing Aircraft as the founding contract. He has published over 60
conference and journal papers and reports and has given invited talks at several universities and
organizations including the NATO/AGARD lecture series LS-205 on adaptive structures and
health monitoring. He holds three patents (co-inventor) on antenna technologies. Dr. Kudva was
honored with the SPIE Smart Structures and Materials Lifetime Achievement Award in 2007 and
the AIAA ASME Adaptive Structures Prize in 2010. He is also an AIAA Fellow (2015). Dr.
Kudva has been an adjunct professor at the Aerospace and Mechanical Engineering Department
at USC since 2015.
Review and Assessment of Airframe Repair Schemes
M M Ratwani and J N Kudva, NextGen Aeronautics Inc. Torrance, CA, USA
S G Sampath, US Army (Retired)
Abstract
This review paper discusses the application of conventional and new repair technologies to in-
service aircraft to enhance structural integrity and safety while at the same time reducing
maintenance costs. Repair procedures for metallic aircraft with composite components and
sandwich structures using composite patches are discussed. Tools and procedures needed to
prepare surfaces for bonded repairs and advantages of using bonded repairs for cracked metallic
components are presented.
The importance of surface preparation and proper material selection for bonded structures is
emphasized. Key steps to be followed for high quality repairs are outlined. The procedures
described may seem simple and routine; however, they play an important role in the performance
of repairs to assure structural integrity of repaired components.
Prof. Afzal Suleman, University of Victoria, Canada
Afzal Suleman is a Professor and Canada Research Chair in Aerospace Systems at the University
of Victoria. He is currently the Director of the Center for Aerospace Research on Unmanned Air
Systems at the University of Victoria where he collaborates with Boeing USA, Bombardier
Canada and Department of Defence in Canada. He is also an Adjunct Faculty at the Technical
University of Lisbon – Instituto Superior Tecnico in Lisbon, Portugal. The focus of Afzal’s
research is on multidisciplinary design optimization of next generation, environmentally efficient
and novel aircraft configurations. He leverages Unmanned Air Systems technology for
experimental validation and airworthiness evaluation. He was the coordinator of the EU funded
project on Novel Air Vehicle Configurations: from fluttering Wings to Morphing Flight
(NOVEMOR) and has participated in EU projects (ARTIMA, 3AS, SMORPH). He has
authored/co-authored over 120 scientific journal publications and over 250 conference papers
and two patents. He has also supervised 33 PhD and 80 MSc theses in diverse areas such as
aeroelasticity, aeroacoustics, multidisciplinary design optimization, advanced composite
structures, structural health monitoring, unmanned air systems and small satellites. Afzal holds a
BSc (Honours) and MSc. in Aeronautical Engineering from Imperial College of Science and
Technology, London and a PhD in Space Dynamics from the University of B.C. He is an
alumnus of the International Space University. Between 1992-1994, he was a Post-Doctoral
Research Fellow at the U.S. Air Force where he researched active aeroelastic control of flexible
aircraft. He is a member of NATO Applied Vehicle Technology Panel, Government of Canada
Armed Forces Defense Advisory Board and the Space Advisory Board. He has been a national
delegate at the United Nations Committee on Peaceful Uses of Outer Space between 1999-2006.
He is a Fellow of the Canadian Academy of Engineering (Canada), the Royal Aeronautical
Society (UK) and the Royal Academy of Sciences of Lisbon (Portugal), and Associate Fellow of
the American Institute of Aeronautics and Astronautics (USA).
Monitoring Aircraft Load Spectrum towards an Integrated Structural Health
Management
A Suleman
Canada Research Chair and Professor
University of Victoria
Victoria, BC, CANADA
E-mail: [email protected]
Abstract
As existing aircraft remain in-service longer, and as new and multifunctional composite
materials replace conventional metal airframes, are resulting in new structural damage scenarios
that may not be detected using current non-destructive inspection techniques, or estimated using
current life prediction methods. Furthermore, if the usage of an aircraft changes from the original
load design spectrum, then the life of critical components can dramatically change and the effect
on critical load bearing components cannot be determined. One possible solution is to use
sensors to measure the in-flight load spectrum that is needed to more accurately predict the
remaining useful life of the component. The load spectrum can be combined with a diagnostics
structural integrity monitor based on a physics-based life management process, and a prognostics
process can be used to determine the remaining useful life followed by a health management of
the structure. However, difficulties with the development of cost-effective health monitoring
technology and reliable prognostics have challenged its practical use and exploitation.
This lecture will provide a consolidated view of current research on structural health monitoring;
including a flight test program to identify issues related to the practical implementation of
condition-based monitoring systems and provides a strategic roadmap for future development
and exploitation.
Prof. Lalita Udpa, Michigan State University, USA
Lalita Udpa received her Ph.D. in Electrical Engineering from Colorado State University. After a
stint of 11 years at Iowa State University, she is currently a University Distinguished Professor in
the department of Electrical and Computer Engineering at Michigan State University. Dr. Udpa
works primarily in the broad areas of Nondestructive Evaluation, Signal Processing and
Analysis. Her research interests include various aspects of NDE such as development of
computational models for NDE, new sensor design, signal and image processing, data fusion,
and inverse problem solutions. Dr. Udpa is a Fellow of the IEEE and a Fellow of the American
Society of Nondestructive Testing and Indian Society of Nondestructive Testing. She serves as
associate technical editor of Research Techniques in NDE and is an editor of IEEE Transactions
on Magnetics.
Electromagnetic NDE Activities at MSU on Aging Aircraft NDE
Prof. Lalita Udpa
Michigan State University, USA
Abstract
Life of average aircrafts in commercial and military fleets is growing and so is the demand for
reliable NDE techniques that assures the structural integrity of aircraft. This talk will first give a
brief review of some of the strategies, challenges and capabilities in aircraft NDE. The talk will
then present an overview of research activities in electromagnetic NDE for aircraft structures. In
particular, the talk will focus on multi-layered riveted geometry in airframe structures with a
review of work carried out on magneto-optic imaging, magneto resistive imaging for crack
detection at fastener holes. Some recent work on microwave imaging for detecting disbands in
metal composite joints will also be presented.
Prof. Sankaran Mahadevan, Vanderbilt University, USA
Sankaran Mahadevan is John R. Murray Sr. Professor of Civil and Environmental Engineering
and Professor of Mechanical Engineering at Vanderbilt University, Nashville, Tennessee, where
he has served since 1988. At Vanderbilt, he also serves as Director of the M.Eng. program in
Risk, Reliability and Resilience Engineering, and as Co-Director of the Laboratory for Systems
Integrity and Reliability (LASIR).
Professor Mahadevan’s research interests are in reliability and uncertainty analysis of civil,
mechanical and aerospace systems, model validation, material degradation, structural health
monitoring, design and manufacturing optimization, and system resilience. His research has been
funded by NSF, NASA, FAA, DoE, DoT, DoD, NIST, Nuclear Regulatory Commission, General
Electric, Northrop Grumman, General Motors, Chrysler, Union Pacific, Siemens, Transportation
Technology Center, and the Sandia, Los Alamos, Idaho and Oak Ridge National Laboratories.
Professor Mahadevan’s research has been documented in over 600 technical publications,
including two books and 300 peer-reviewed journal papers. He has directed 42 Ph.D.
dissertations and 24 M. S. theses, and has taught many industry short courses on uncertainty and
reliability analysis methods.
Professor Mahadevan’s current professional service activities include Managing Editor, ASCE-
ASME Journal of Risk and Uncertainty in Engineering System; and Associate Editor for two
other journals (ASCE Engineering Mechanics, ASTM Smart and Sustainable Manufacturing).
Professor Mahadevan is a Fellow of American Institute of Aeronautics & Astronautics,
Engineering Mechanics Institute (ASCE), and the Prognostics & Health Management Society.
Professor Mahadevan earned his Ph.D. at the Georgia Institute of Technology, Atlanta, Georgia,
M.S. at Rensselaer Polytechnic Institute, Troy, New York, and B.Tech. at the Indian Institute of
Technology, Kanpur.
Digital Twin Technology for Aircraft Health and Operations Management
under Uncertainty
Prof. Sankaran Mahadevan
Vanderbilt University, Nashville, TN, USA
Abstract
A digital twin is a computer model that contains all the information collected about an
engineering system, including design details, manufacturing process effects, system properties,
physics behavior models of the system and components, operational history, and health
monitoring (inspection, maintenance, repair) data. Such a digital twin can be used to (i) assess
the system’s current condition and capabilities, (ii) predict the future condition and capabilities
of the system, and (iii) support decision making related to system health management
(inspection, maintenance, and repair) and operational strategies (such as mission profiles). The
digital twin is continuously updated with real-time information as it becomes available. Two
desirable features in this regard are fusion of multiple sources of information, and accounting for
multiple sources of uncertainty in modeling and measurement. As a result, the digital twin
approach offers several benefits: (i) it supports decision-making with comprehensive information
about the system’s current and future states; (ii) it reduces the system risk by taking advantage of
monitoring, information fusion, and timely corrective actions such as repair; and (iii) it reduces
the cost of extensive testing and analysis by fusing all available information.
The digital twin concept has become feasible and popular during the past decade, due to the
advances in sensing, communication and computing technologies, and machine learning
algorithms. Many different industries are currently studying this concept and developing suitable
approaches for system health and quality management. This talk will present the concepts,
techniques, and implementation challenges of digital twin technology. In particular, the talk will
discuss a Bayesian network approach for information fusion and uncertainty quantification in the
diagnosis and prognosis of system health and reliability. These techniques will be illustrated for
several mechanical systems, focusing both on health management and operational decision
making for aircraft and rotorcraft structures [1, 3].
References
1. Li, C., Mahadevan, S., Ling, Y., Choze, S., and Wang, L., “Dynamic Bayesian Network for
Aircraft Wing Health Monitoring Digital Twin,” AIAA Journal, Vol. 55, No.3, pp. 930-941,
2017.
2. Karve, P., Guo, Y., Kapusuzoglu, B., Mahadevan, S., and Mulugeta, H., “Digital Twin
Approach for Damage Tolerant Mission Planning under Uncertainty,” Engineering Fracture
Mechanics, 2019, in press.
3. Ling, Y., and Mahadevan, S., “Integration of Structural Health Monitoring and Fatigue
Damage Prognosis,” Mechanical Systems and Signal Processing, Vol. 28, pp. 89-104, 2012.
Effect of Newly Promulgated Environmental Rules
Prakash C Patnaik
Structures, Materials and Performance Laboratory, Aerospace Research Centre
National Research Council of Canada. Ottawa
Abstract
The global environmental regulations/guidance have been driving the aerospace and defence
industries to invest in developing, qualifying and implementing environmentally compliant
materials and processes, including hard chrome plating and cadmium plating alternatives for
various applications. The environmental legislature can impact on defence platforms anywhere
through the CADMID (Concept Assessment Development Manufacturing In-Service Disposal)
life cycle. However, in the context of interoperability between nations, the legislature would
require a common framework between countries to adopt the available alternative technologies
for air vehicles both for civil and defence applications. To this end, continuing exchange of
information, knowledge, best practice activities is highly desired.
This presentation will review the latest guidelines and present some of the recommendations and
harmonization of consumables and processes in the industry. Furthermore, selected technologies
are demonstrated such as HVOF cermets, Zn-Ni plating, IVD aluminium coating and
AlumiPlate® coating aiming for hard chrome and cadmium replacing developed in Canada and
other countries.
Dr K Vijayaraju, Aeronautical Development Agency, India
BE(Metallurgy), 1984, Indian Institute of Science, Bangalore; M Sc (Engg-Met), 1987, Indian
Institute of Science, Bangalore; Ph D(Aerospace), 2000, Indian Institute of Science, Bangalore
Joined Aeronautical Development Agency - ADA in 1987 and has been with ADA since then.
Currently Outstanding Scientist and Group Director (Composites and Fatigue).
Coordinates the airframe team for the structural design of the Advanced Medium Combat
Aircraft (AMCA) in addition to the responsibilities for the Fatigue, HUMS and Composite
groups of ADA.
Participated through the entire range of development activities of LCA structures - from
Preliminary Design to its induction into service, specifically, in the development of Composites
Technology for LCA aircraft structures
Contributed to, in particular, on behavior of composites at various levels, from raw materials to
small structural details to full-scale components. This has led to high confidence in the Design
Allowables used for the design of composites and sorted out various certification issues.
Conceptualized the Health and Usage Monitoring System (HUMS) for LCA to monitor LCA
airframe fatigue usage and led the team on its implementation to LCA-AF-Mk1. This system is
now a standard fit to all Series Production Aircraft.
Coordinated the indigenization of carbon fibres at NAL through a DRDO-ADA programme
(2004 - 2008)
Coordinated the "Development Initiatives for Smart Aircraft Structures" (DISMAS),
spearheading the application of smart materials and MEMS for aircraft applications (2004 -
2009)
Project Director (2008 - 2016) of the National Program on Smart Materials and Structures
(NPMASS), leading the R & D on smart materials, advanced sensors, MEMS and related
technologies.
Interests are in a broad range of subjects – advanced materials, fatigue, damage tolerance, testing
of aircraft structures, health monitoring and management, micro and smart systems technology
Honored in 2015 by Institute for Smart Structures and Systems for his contributions to Smart
materials and Microsystems technology.
Been Chairman of several review committees and DRDO panel on Sensor development
Member of several DRDO, ARDB, DST, MeitY panels at the national level.
Life Member of Professional bodies - ISAMPE, AeSI, ISSS and InSIS and has been President of
ISAMPE.
Published around 25 papers in International and National Journals & Conferences.
Also, currently holds the post of Adjunct Professor of Aerospace Department, IIT Kanpur
Technology Insertion into a Combat Aircraft: Opportunities and Challenges
K Vijayaraju, OS
Group Director (Composites & Fatigue)
Aeronautical Development Agency,
PB No: 1718, Vimanapura Post, Bangalore 560 017
Email: [email protected]
Abstract
Combat aircraft development programmes incorporate advanced materials and technologies to
realize the highly demanding performance goals of the platform and also to ensure that the
platform serves the intended users for long time without exorbitant life cycle cost. Judicious
insertion of technologies into the design and development of the platform are extremely
important not only to build a contemporary fighter to serve the intended purpose but also to
deliver economically viable service life and a sustainable maintainability. In the Indian military
aircraft ecosystem, the Light Combat Aircraft (LCA), a multirole, single engine fighter, an
indigenous platform that has entered only recently the user service. It is, therefore, quite evident
that there would be no aging aircraft issues to discuss. However, it is well known that the
technology choices made during the design and build phases of the platform determines the
success and limitations of the platform for rest of its life cycle including aging characteristics. It
is on this premise; the author intends to present two examples of technology insertions which
were affected during the evolution of LCA-AF-Mk1. These are, namely, large scale use of fibre
reinforced composite materials in the airframe and Health and Usage Monitoring System
(HUMS) developed for the fatigue life monitoring of the aircraft with Individual Aircraft
Tracking (IAT). As these technologies were being introduced for the first time into an aircraft
platform being designed and developed indigenously, there were challenges in realizing them to
exploit the benefits offered by these technologies. The presentation will discuss the background
and challenges encountered during the insertion of these two technologies into LCA
Dr Prakash Mangalgiri, Indian Institute of Technology Kanpur, India
Dr Prakash D Mangalgiri graduated from VRCE (now VNIT) Nagpur and then got his M E
(Mech) and Ph D (Aerospace) from IISc, Bangalore. He has worked in various prestigious
organisations such as, TELCO (now Tata Motors), IISc, NASA Langley Research Center USA,
Aeronautical Development Agency (ADA) Bangalore, General Motors (R&D), Bangalore and
IIT Kanpur. He is currently Visiting Professor in the Aerospace Dept of IIT Kanpur.
Dr Mangalgiri's research interests have spanned the entire spectrum – “cradle to grave” - of
structural technology, from raw materials to final failure. His contributions are especially
noteworthy in areas of advanced composites technology, designing with composites, failure
mechanics, fatigue, damage tolerant design and development and use of smart technology. His
work on various issues related to use of composites in primary structures of aircraft not only
facilitated the large-scale use of carbon fiber composites in the Light Combat Aircraft Tejas, but
also led to the development of composite technology in India in general. His work in automotive
sector covered crashworthiness, use of smart materials in automobiles and virtual manufacturing.
His interest in Structural Integrity issues has led to bringing in Structural Health Monitoring and
then Integrated Vehicle Health Monitoring to the fore to be taken up for development in the
country. Currently, he is engaged in teaching Aircraft Structural Integrity and Composite
Structures at IIT Kanpur and exploring new areas for research such as stealth structures, aircraft
lifing issues and IVHM.
Apart from his technical contributions, Dr Mangalgiri has played a vital role in framing,
managing and implementing small and large research projects in the country, working with
numerous institutions and researchers. His initiatives have led to development of the crucial
carbon fibre technology in the country along with development of advanced resins. He has been
a key member of the two National Programs - NPSM and NPMASS - for smart materials and
MEMs technology in India and contributed heavily to their success. Dr Mangalgiri also served as
expert member on various committees and R&D Boards of Govt of India, such as AR&DB and
DST.
Dr Mangalgiri has more than 100 publications of which more than 50 papers are published in
refereed journals and conferences. He has also written more than 100 internal technical reports in
ADA and GM-R&D. He has also edited three books and has lectured widely. He has received
several awards and felicitations for his work. He has been President of ISAMPE and ISSS. He is
a Fellow of the Aeronautical Society of India and Distinguished Alumnus of the Aerospace Dept
of IISc.
An Overview of Corrosion Monitoring for Aircraft – Problems and Prospects
Prakash D Mangalgiri,
Visiting Professor, Aerospace Dept, IIT Kanpur 208016
Abstract
Among the several concerns that crop up during the operation of an ageing aircraft, perhaps the
most worrying issue for a structural engineer is the appearance of corrosion. This is so in spite of
the extensive knowledge generated over last several decades of the corrosion phenomena of Al-
alloys, steels and other materials used in aircraft structures. Certainly, the existence of corrosion
and its ill-effects on the structural behaviour have been recognised by aircraft engineers, and a
strategy to deal with them is usually provided in a Corrosion Prevention and Control Plan
(CPCP). Such a plan comprises of corrosion prevention strategies by design, and periodic
inspections and corrective actions as a part of the scheduled maintenance. The basic philosophy
in the aircraft industry appears to be that corrosion should be prevented through use of
anticorrosive surface treatments, coatings, paints, etc. and, if it does happen, should be detected
at periodic inspections; and if detected, should be “repaired”. Unfortunately, there is enough
evidence to suggest that in reality the structural integrity of the aircraft does get compromised by
corrosion, more so as the aircraft ages and significant costs may be incurred in avoiding risks of
structural failure. Over last couple of decades, the paradigm of structural health monitoring has
seen significant advances giving rise to the hope of catching the occurrence of structural damage
much before it becomes a problem. However, much of this effort has focused on mechanical
damage such as cracks and similar flaws in metals and impact damage and delaminations in
composites, as well as on their growth under operational loads through processes such as fatigue.
It is of course desirable that corrosion damage also be sensed and monitored, its criticality
assessed and its growth predicted, thus ensuring availability of aircraft for safe operation.
An attempt is made in this talk to examine developments in corrosion monitoring techniques and
highlight issues in their incorporation into an SHM framework of an aircraft or aircraft fleet.
Two basic approaches for corrosion monitoring are considered: one, direct monitoring of
corrosion damage, use of coupons and surrogates, and also electrochemical techniques and the
other, indirect monitoring through monitoring corrosivity of the environment, and through
monitoring degradation in corrosion prevention coatings. Most of these developments can be
seen as an evolution from the non-destructive testing (NDT) techniques to detect corrosion. In
recent times, corrosion sensing and monitoring are increasingly using developments in ‘smart
technology’, such as smart coatings, thin-film technology, piezo sensors and guided waves, smart
materials such magneto-resistive and magneto-optical, optical fibres, smart polymers, and micro
devices fabrication. On the whole, though, there are significant gaps which are inhibiting
application and use of the developed techniques in practice. It is expected that the issues
highlighted here will be of relevance not only for ageing aircraft but also for new aircraft under
design or in operation.
Mr. Yogesh Kumar, CSIR-NAL, India
Yogesh Kumar, a distinguished alumnus from Punjab Engineering College Chandigarh and IIT
Madras, is a renowned technologist in the field of Aircraft and Aircraft systems. During his
career (all in R&D) at Hindustan Aeronautics Ltd. (HAL) a leading Aerospace Organization, he
has successfully led a number of major R&D programmes; notable amongst those was the
India’s pride the Light Combat Aircraft (LCA). LCA now is in regular production at HAL. He
also led the Design teams for development of Intermediate Jet Trainer (IJT), and major upgrade
of Jaguar aircraft; both done in record time.,
Yogesh Kumar also led a team at Lucknow which did pioneering work on development of a
number of Systems and Accessories (about 100 in number) for various aircraft. All are currently
flying. He and his team also developed a pilot plant for Alternate Energy system for power
generation using organic fluid-based turbine.
Author of about 24 Scientific and Technical papers and over 50 keynote addresses and lectures
to reputed organizations, Yogesh Kumar is a proud recipient of following National/International
awards;
• Noel Derr Gold Medal – 1987 (based on his work related to alternate energy systems)
• National acclamation Prize – 1988
• National Aeronautical Prize – 2000
• Scientist of the Year Award – 2001
• International Project Management Award – 2005; considered an ‘Oscar’ in Project
Management.
• Raksha Mantri Award for Import Substitution - 2006
• Sammana Patra by Karnataka State-2005
• Life Time Achievement Award – 2006
• Distinguished Alumnus Award of Excellence from Punjab Engineering College - Nov.2019
Yogesh Kumar has also authored a Book titled “Lead and Execute- Art of Managing Large Scale
Projects”. It was formally launched on 18th December 2014 at HAL Management Academy,
Bangalore. It evoked very good response with about 640 sold to various aerospace organizations
(Public and Private), R&D Labs, Academic Institutes, and aeronautical enthusiasts in a short
period of about two years from its launch.
Yogesh Kumar is a Fellow, Aeronautical Society of India and was Member, American Institute
of Aeronautics and Astronautics.
After superannuating from HAL where he was Member of the Board as Director (LCA) in
September 2006, he is currently working as Adviser to NAL/CSIR; a Govt. of India Research
and Development Organization in Aerospace.
Ageing Avionics
Yogesh Kumar
Former Director (LCA), HAL
Adviser, CSIR-NAL
Abstract
Starting from the contribution of systems and LRUs towards the production cost of a typical
aircraft, the paper deals with global scenario on aerospace and defence with focus on avionics
segment. To illustrate the problem of ageing, it mentions how much it costs to maintain avionics
at depot level; and why we need avionics upgrade; what are the challenges faced etc. India’s
initiatives towards that are highlighted.
Taking CSIR-NAL as an example, how the capabilities in this vital field have evolved are
mentioned with challenges and opportunities. Health Management and Technology Insertion,
vital tools towards ageing of avionics have also been addressed.
In the end, a case study on Jaguar Avionics’ upgrade program; one of the largest on upgrades in
the time period 2000 to 2006 has been given.
Mr. H R Sudarshan Prasad, Centre of Excellence, Aerospace and Defence, India
Sri H.R. Sudarshan Prasad graduated in engineering from Bangalore University with distinction
in 1971 and joined Hindustan Aeronautics limited after completing the design trainee training at
Indian Institute of Science, Bangalore. He has a rich experience of 39 years in the area of fixed
wing aircraft design and development, integration and flight testing. His core competence is
avionics and electrical system design, design of cockpit controls and display systems. He has
worked extensively on all aircraft design and development projects of HAL including basic
trainers, intermediate trainers and fighter aircraft including Tejas aircraft and its variants. He was
responsible for the design, development, testing and certification of electrical power generation
and distribution system of Tejas aircraft. Technical challenge was to provide uninterrupted
electrical power to meet stringent requirements of digital flight control system with dissimilar
redundancy. He was awarded Dr V M Ghatge memorial award by Aeronautical Society of India
in 2001 for his contribution to Tejas aircraft programme. After superannuating in 2010 as
General Manager, Aircraft research and design centre, HAL in 2010 he worked as consultant at
Aeronautical Development Agency (ADA). Currently, he is working at the Centre of Excellence,
Aerospace and Defence, Bangalore as an expert faculty imparting training to engineering
students and also graduate engineers.
Aging of Aircraft Electrical Wiring
H R Sudarshan Prasad
Abstract
Impact of aging on Aircraft Electrical Wiring is often difficult to identify. The electrical wiring
of many older aircraft still in service was designed to be in the ‘fit and forget’ category.
However, both age itself and inadvertent collateral damage during scheduled maintenance or
routine inspection cause airworthiness problems. Wiring degradation has been found to be
caused by installation, environment and maintenance factors. Wire insulation deteriorates
through factors such as aging and temperature cycling. The disruptive effects of maintenance
activity can be more than the environmental factors that can lead to accelerated wire degradation.
Maintenance practices should focus on maintaining the integrity of wiring.
Typical faults noticed in electrical looms, cables and connectors include broken conductors,
overheated conductors, chafed insulation, contamination, connector damage etc. Good routing
and installation practices coupled with careful handling of wiring especially during aircraft
maintenance helps in ensuring the integrity of the aircraft wiring.
New technologies like ‘live wire testing’ of aircraft wiring during flight, arc fault circuit
interrupter technology and embedding of nanoscale sensors in the wiring are being developed to
further enhance the safety of the aircraft wiring. In the longer run fiber optics and wireless
technologies will reduce the need for bulky wiring looms.
Dr A R Upadhya, Jain University, India
Dr. A R Upadhya holds B.Tech and M.E. degrees in Aeronautical Engineering from IIT
Kharagpur and Indian Institute of Science respectively, and a PhD from Cranfield Institute of
Technology (now Cranfield University), UK. He served as a Scientist at the CSIR – National
Aerospace Laboratories initially during 1974-1986 and then as its Director during 2004-2011.
In between, he was associated with the design and development of the Light Combat Aircraft at
the Aeronautical Development Agency, MoD in the areas of Loads, Dynamics and Aero-Servo-
Elasticity. Post superannuation, he was appointed as Dr. Raja Ramanna DRDO Distinguished
Fellow of the Department of Defence Research, MoD at ADA for a period of 4 years. Presently
he is a Distinguished Professor at Jain University, Vice Chairman of NALTECH and Convener
of Sectional Committee on Aerospace Engineering of Indian National Academy of Engineering
(INAE) and Honorary Secretary of its Bangalore Chapter, Member of Pogramme Monitoring
Board of Jain University, Academic Council of JSS S&T University, Mysore and Academic
Senate of Visveswaraya Technological University, Belagavi, Karnataka. He was also the
Programme Director of the first National Programme on Smart Materials & MEMS, Vice
Chairman of the Executive Board of the second National Programme, and the Convener of the
Technical Committee of Aeronautical Research and Development Board, MoD. Dr Upadhya’s
contributions have been recognised with the Distinguished Alumnus Award of IIT Kharagpur
and of the Department of Aerospace Engineering, Indian Institute of Science, Platinum Jubilee
Award of the same Dept, Visvesvaraya Vijnana Puraskar of Swadeshi Vijnana Andolana in
2008, “Engineering Personality” honour by the IE(India) in 2009, and Honorary Member of
ISAMPE in 2010, Presentation of Citation IE(India), Rajasthan State Centre in 2010, and the
Institute of Smart Structures and Systems(ISSS) in 2012 . He is a Fellow of the Indian National
Academy of Engineering (INAE) and Aeronautical Society of India. He had also served as
President of ISSS and ISAMPE.
Structural Life Management in a Combat Aircraft
Prakash D Mangalgiria and A R Upadhyab aVisiting Professor, Aerospace Department, IIT Kanpur 208016,
Email: [email protected] bDistinguished Professor, IIAEM, Jain University, Bangalore 562112,
Email: [email protected]
Abstract
The paper briefly describes some of the underlying concepts, issues and strategies for ensuring
efficient management of structural integrity of an airframe throughout the useful life of an
aircraft – especially that of a military combat aircraft. Much of the discussion in the paper is
based on the experience of the authors during the design and development phase of the Indian
Light Combat Aircraft, namely, LCA Mk-I Tejas, and the information available about the LCA
in the open literature or public domain. Even though not an ageing aircraft, LCA is taken as an
example to facilitate bringing out various issues and strategies to resolve them, particularly with
relevance to the Indian aeronautical scenario. The use of both metallic and composite materials
in modern combat aircraft structures necessitate different design strategies to be adopted for their
structural integrity throughout the life time. In this respect too, the LCA serves as a good
example. Within the limited scope of the paper, the description and discussions are primarily
limited to some of the important aspects, such as the fatigue degradation in metallic materials
and impact damage in composites – which do form the bulk of the effort of life management of
airframe structures. Other issues such as corrosion in metals and environmental degradation in
composites are also briefly mentioned. A brief description of the aircraft and its structure is given
initially. Major steps in designing for structural life management, such as, estimation of static
loads, derivation of fatigue spectra for the intended usage, degradation through fatigue or impact
damage, lifing philosophies, estimation of life and monitoring of health and usage of individual
aircraft are described. A brief mention is also made about Structural Health Monitoring (SHM)
as a future direction in life management.
It is expected that the exposition in the paper will help understand issues and strategies that
would eventually be required as a combat aircraft gets aged in the service.
Dr. Ramakant Singh, DGCA, India
Dr. Ramakant Singh completed his graduation in Aeronautical Engineering in 1987 and Master
degree in Space Engineering and Rocketry in 1989. He completed his PhD in Composites in
1996. His work was related to study of buckling behaviour of glass fibre and carbon fibre based
composite plates.
He was appointed in Civil Aviation Department (DGCA-India) in 1993 as Project Officer. Since
then, he is continuing in the same organisation.
Presently, Dr. Singh is working as Director (Aircraft Engineering) in DGCA (India) and posted
at Bangalore. His present work involves certification of aircraft and its parts and appliances for
civil aviation applications.
Regulatory Aspect of Ageing Civil Aircraft
Dr. Ramakant Singh
Director, Aircraft Engineering
DGCA, India
Abstract
There is no single criterion that defines an aircraft as ‘old’. The age of an aircraft depends on
factors including the chronological age, the number of flight cycles, and the number of flight
hours. Some ageing mechanisms such as fatigue occur through repetitive or cyclic loading.
While others, such as wear, deterioration, and corrosion occur over time. If not managed, these
ageing mechanisms can be a significant safety concern.
India as a Contracting State to ICAO, has obligations to ensure the continuing airworthiness of
the aging aircraft. A continuing structural integrity programme exists as a part of aircraft type
design which includes specific information concerning corrosion prevention and control.
Compliance to continuing airworthiness of aging aircraft is ensured through such programmes.
Depending on the structural design criteria, the Structural Integrity Programme for aircraft
(sometimes referred to as the ageing aircraft programme) include the following:
a) Supplementary structural inspection programme,
b) Corrosion prevention and control programme,
c) Service bulletin review and mandatory modification programme,
d) Repairs review for damage tolerance, and /or
e) Widespread fatigue damage (WFD) review.
The corrosion prevention and control programme should be initiated as early as possible in the
service life of the aircraft and should preferably be available when the aircraft is introduced into
service. The other elements of the continuing Structural integrity programme should be
developed once sufficient service experience has been accumulated; normally they should be
initiated by the time that the lead aircraft has reached the half design life goal for the type and be
reviewed periodically.
In line with the vision of DGCA to promote efficient air transportation, it is necessary to define
the term ‘aging’ of an aircraft not only on technical terms but also on economic and financial
aspects, which have a long term impact on aircraft maintenance costs.
