Integrated Vehicle Health Management Systems Research Articles

Trend in tropopause warming and its influence aircraft performance

PurposeTemperature anomalies in the upper troposphere have become a reality as a result of global warming, which has a noticeable impact on aircraft performance. The purpose of this study is to investigate the total air temperature (TAT) anomaly observed during the cruise level and its impact on engine parameter variations.Design/methodology/approachEmpirical methodology is used in this study, and it is based on measurements and observations of anomalous phenomena on the tropopause. The primary data were taken from the Boeing 747-8F's enhanced flight data recorder, which refers to the quantitative method, while the qualitative method is based on a literature review and interviews. The GEnx Integrated Vehicle Health Management system was used for the study's evaluation of engine performance to support the complete range of operational priorities throughout the entire engine lifecycle.FindingsThe study's findings indicate that TAT and SAT anomalies, which occur between 270- and 320-feet flight level, have a substantial impact on aircraft performance at cruise altitude and, as a result, on engine parameters, specifically an increase in fuel consumption and engine exhaust gas temperature values. The TAT and Ram Rise anomalies were the focus of the atmospheric deviations, which were assessed as major departures from the International Civil Aviation Organizations–defined International Standard Atmosphere, which is obvious on a positive tendency and so goes against the norms.Research limitations/implicationsNecessary fixed flight parameters gathered from the aircraft's enhanced airborne flight recorder (EAFR) via Aeronautical Radio Incorporated (ARINC) 664 Part 7 at a certain velocity and altitude interfacing with the diagnostic program direct parameter display (DPD), allow for analysis of aircraft performance in a real-time frame. Thus, processed data transmits to the ground maintenance infrastructure for future evaluation and for proper maintenance solutions.Originality/valueA real-time analysis of aircraft performance is possible using the diagnostic program DPD in conjunction with necessary fixed flight parameters obtained from the aircraft's EAFR via ARINC 664 Part 7 at a specific speed and altitude. Thus, processed data is transmitted to the ground infrastructure for maintenance to be evaluated in the future and to find the best maintenance fixes.

Development and Implementation of a Framework for Aerospace Vehicle Reasoning (FAVER)

This paper discusses the development and implementation of the architecture of a Framework for Aerospace Vehicle Reasoning, `FAVER'. Integrated Vehicle Health Management systems require a holistic view of the aircraft to isolate faults cascading between aircraft systems. FAVER is a system-agnostic framework developed to isolate such propagating faults by incorporating Digital Twins (DTs) and reasoning techniques. The flexibility of FAVER to work with different types and scales of DTs and diagnostics, and its ability to adapt and expand for previously unknown faults and new systems are demonstrated in this paper. The paper also shows the novel combination of relationship matrix and fault attributes database used to structure the knowledge of FAVER's expert system. The paper provides the working mechanism of FAVER's reasoning and its ability to isolate faults at the system level, identify their root causes, and predict the cascading effects at the vehicle level. Four aircraft systems are used for demonstration purposes: i) the Electrical Power System, ii) the Fuel System, iii) the Engine, and iv) the Environmental Control System, and the use case scenarios are adapted from real aircraft incidents. The paper also discusses the pros and cons of FAVER's reasoning via demonstrations and evaluates the performance of FAVER's reasoning through a comparative study with a supervised neural network model.

Real-Time Maintenance Optimization Considering Health Monitoring and Additive Manufacturing

Prognostics Health Management (PHM) and Integrated Vehicle Health Management (IVHM) are extensive areas of research. Whereas a lot of work has been done in diagnostics and prognostics, economic viability is an important consideration. The availability of aircraft in the aerospace sector is a critical factor. Thus, cost and downtime are the main parameters to assess the impact of IVHM. Additionally, new repair technologies, such as additive manufacturing (AM), have the potential to become standard repair procedures, complementing IVHM, and its viability also has to be assessed. However, to accurately study the impact of these factors, the characteristics of aerospace maintenance have to be taken into account. Several approaches are followed in aircraft maintenance, depending on cost, downtime and aircraft availability constraints. For instance, some parts can be repaired on the ground and assembled again on the same aircraft, while single Line Replaceable Units (LRUs) need to be removed, replaced and later repaired in the workshop without affecting the availability of the aircraft. With the gradual introduction of IVHM, the viability of any new IVHM technology needs to be assessed.This paper describes an extensive cost and downtime model to take into account all these scenarios, including the impact of using different types of IVHM systems. The impact of IVHM and new repair technologies is discussed comparing maintenance cost and downtime of parts of LRUs and parts repaired when the aircraft is on the ground.Secondly, a real-time maintenance case study based on IVHM, a cost and downtime model and additive manufacturing is presented. This application allows the optimization of maintenance activities by updating the available resources and their corresponding cost and time, along with the actual prediction of the Remaining Useful Life (RUL) using a health monitoring system, instead of depending on historical component/sub-system failure probabilities.

Integrating IVHM and Asset Design

Integrated Vehicle Health Management (IVHM) describes a set of capabilities that enable effective and efficient maintenance and operation of the target vehicle. It accounts for the collecting of data, conducting analysis, and supporting the decision-making process for sustainment and operation. The design of IVHM systems endeavours to account for all causes of failure in a disciplined, systems engineering, manner. With industry striving to reduce through-life cost, IVHM is a powerful tool to give forewarning of impending failure and hence control over the outcome. Benefits have been realised from this approach across a number of different sectors but, hindering our ability to realise further benefit from this maturing technology, is the fact that IVHM is still treated as added on to the design of the asset, rather than being a sub-system in its own right, fully integrated with the asset design. The elevation and integration of IVHM in this way will enable architectures to be chosen that accommodate health ready sub-systems from the supply chain and design trade-offs to be made, to name but two major benefits. Barriers to IVHM being integrated with the asset design are examined in this paper. The paper presents progress in overcoming them, and suggests potential solutions for those that remain. It addresses the IVHM system design from a systems engineering perspective and the integration with the asset design will be described within an industrial design process.

Opportunities for Explainable Artificial Intelligence in Aerospace Predictive Maintenance

This paper aims to look at the value and the necessity of XAI (Explainable Artificial Intelligence) when using DNNs (Deep Neural Networks) in PM (Predictive Maintenance). The context will be the field of Aerospace IVHM (Integrated Vehicle Health Management) when using DNNs. An XAI (Explainable Artificial Intelligence) system is necessary so that the result of an AI (Artificial Intelligence) solution is clearly explained and understood by a human expert. This would allow the IVHM system to use XAI based PM to improve effectiveness of predictive model. An IVHM system would be able to utilize the information to assess the health of the subsystems, and their effect on the aircraft. Even if the underlying mathematical principles are understood, they lack an understandable insight, hence have difficulty in generating the underlying explanatory structures (i.e. black box). This calls for a process, or system, that enables decisions to be explainable, transparent, and understandable. It is argued that research in XAI would generally help to accelerate the implementation of AI/ML (Machine Learning) in the aerospace domain, and specifically help to facilitate compliance, transparency, and trust. This paper explains the following areas:
 
 Challenges & benefits of AI based PM in aerospace
 Why XAI is required for DNNs in aerospace PM?
 Evolution of XAI models and industry adoption
 Framework for XAI using XPA (Explainability Parameters)
 Discussion about future research in adopting XAI & DNNs in improving IVHM.

Progress towards a Framework for Aerospace Vehicle Reasoning (FAVER)

This paper proposes a reasoning framework to diagnose faults at the vehicle level in a complex machine like an aircraft. The current focus of Integrated Vehicle Health Management (IVHM) is on diagnosing and prognosing faults at the component and subsystem levels; only a few IVHM systems consider the interaction between the systems. To diagnose faults at the vehicle level, an IVHM System needs a framework that recognizes the causal relationships between systems and the likelihood of fault propagation between them. The framework should also possess an element of reasoning to assess data from all systems, to assign priorities, and to resolve ambiguities. The Framework for Aerospace VEhicle Reasoning (FAVER) that is proposed in this paper uses a digital twin of the aircraft systems to emulate functioning of the aircraft and to simulate the effect of fault propagation due to systems interactions. FAVER applies reasoning that can handle fault signatures from multiple systems in the form of symptom vectors, to detect and isolate cascading faults and their root causes. The blending of a digital twin and reasoning in this framework will enable FAVER to: i) isolate faults that have both local and cascading effects on the concerned systems, ii) identify faults that were previously unknown, and iii) resolve ambiguous faults. This paper explains the different steps involved in developing FAVER and how this framework can be demonstrated in the aforementioned scenarios with the help of different use cases. This paper also talks about the challenges to be faced while developing this framework and ways to overcome them.

Physics-based integrated vehicle health management system for predicting the remaining useful life of an aircraft planetary gear transmission

PurposeIntegrated vehicle health management has been developed for several years in different industries, to be able to provide the required inputs to determine the optimal maintenance operations depending on the actual health status of the system. The purpose of this paper is to demonstrate the potential of a physics-based model (PbM) for prognostics with a real case study, based on the detection of incipient faults and estimate the remaining useful life of a planetary transmission of an aircraft system.Design/methodology/approachMost of the research in the area of health assessment algorithms has been focused on data-driven approaches that are not based on the knowledge of the physics of the system, while PbM approaches rely on the understanding of the system and the degradation mechanisms. A physics-based modelling approach to represent metal-metal contact and fatigue in the gears of the planetary transmission of an aircraft system is applied.FindingsBoth the failure mode caused by metal-metal contact as caused by fatigue in the gears is described. Furthermore, the real-time application that retrieves the results from the simulations to assess the health of the system is described. Finally the decision making that can be executed during flight in the aircraft is incorporated.Originality/valueThe paper proposes an innovative prognostics health management system that assesses two important failure modes of the planetary transmission that regulates the speed of the generators of an aircraft. The results from the models have been integrated in an application that emulates a real system in the aircraft and computes the remaining useful life in real time.

Using Big-data and Surface Fitting to Improve Aircraft Safety Through the Study of Relationships and Anomalies

The aim of this paper is to assess the utility of a Big-Data approach to fault detection for ‘systems of systems’, utilising the derivation of empirical relationships identified through surface fitting. So-called Big-Data Integrated Vehicle Health Management systems do currently exist, but tend to analyse the health of vehicle systems based on the behaviour of individual sensors and readings. This paper proposes that it is possible to consider vehicle systems with a ‘macro’ approach and identify relationships between key variables which may not be initially apparent. Used in this paper is the open source flight simulation software FlightGear which has previously been assessed for the development of fault detection systems with positive results. The relationships found can be combined into a model of expected results against which real-time data is tested. Surface fitting and the assessment of ‘goodness of fit’ is used to identify these relationships. It is proposed that this technique need not be limited to fault detection in vehicle systems but is also applicable to other vital systems which require redundancy and constant health analysis. This paper concludes that this method is a viable approach and that relationships can be successfully identified for fault detection purposes.

Integrated Vehicle Health Management System for Fighter Aircraft

Integrated Vehicle Health Management System for Fighter Aircraft

Maintenance optimization of an aircraft fleet considering IVHM based on cost and availability considering the use of additive manufacturing

PHM and Integrated Vehicle Health Management (IVHM) are extensive areas of research. Whereas a lot of work has been done in diagnostics and prognostics, the economic viability is also an important aspect. The availability of aircraft in the aerospace sector is a critical factor; thus, cost and downtime are the main parameters to assess the impact of IVHM. Additionally, new technologies such as additive manufacturing have the potential to become standard repair procedures and its viability also has to be assessed. However, to accurately study the impact of these factors the particularities of the aerospace sector have to be taken into account. Several systems of the aircraft are considered as part of a single Line Replaceable Unit (LRU) that is replaced, and later repaired in the workshop without affecting the availability of the aircraft when a subcomponent fails; whereas other parts can be repaired while the aircraft is on the ground and assembled again in the same aircraft. This aspect affects the cost and downtime, and also has to be taken into account to assess the viability of any new technology or IVHM system.This paper describes an extensive cost and downtime model to take into account all these scenarios including the impact of using different types of IVHM systems. The impact of IVHM and new repair technologies are discussed comparing maintenance cost and downtime of parts of LRUs and parts repaired on the ground.

Overview of Vehicle Integrated Propulsion Research (VIPR) Testing

Maintaining safe operation of an aircraft is a major emphasis of the NASA Aviation Safety Program [1]. An Integrated Vehicle Health Management (IVHM) system aims to maintain vehicle health through detection, diagnostics, state awareness, prognostics, and lastly, mitigation of detrimental situations for each of the vehicle subsystems and throughout the vehicle as a whole [2]. Major subsystems associated with a vehicle wide IVHM system are the airframe, avionics, and propulsion systems. Each subsystem has its own challenges associated with development of IVHM technologies. One particular challenging subsystem for vehicle health management is related to Propulsion Health Management (PHM). The engine is a complex system with a range of operating components whose failure can affect passenger safety. Reliable operation of these engines is critical for aircraft safety. The harsh environment conditions within an engine often present significant challenges for the integration and application of health management systems. In parallel, diagnostic systems often have to perform evaluations with limited sensor information, while evaluating a complex system whose components include gas path, turbomachinery, hydraulics, and other components. Demonstration of Propulsion Health Management technologies is critical for their commercial acceptance. A major aspect of ongoing NASA Propulsion Health Management work is demonstration of these maturing technologies on an operational engine in series of tests called Vehicle Integrated Propulsion Research, or VIPR. This paper gives a brief overview of the VIPR series of tests, the technologies involved in this testing, and how this approach is being used to advance the commercialization and acceptance of these technologies. VIPR is a means to test and evaluate emerging health management technologies on a commercial engine, incorporating new sensors directly on the engine, providing seeded fault scenarios, and evaluating advances in engine diagnostics. This step is critical in order for IVHM technologies to mature from lab work and simulation demonstrations needed for industry acceptance. This work is in partnership with the Air Force, which has provided access to two F117 high bypass turbofan engines and time on operational planes for the ground-based, on-board engine tests. In these tests, the research engines are instrumented to achieve NASA and partner goals and mounted on a C-17 aircraft, though it is important to note that the planes are grounded and do not take flight. A series of tests are planned with overall Vehicle Systems Safety Technologies (VSST) project objectives of testing health management sensors, sensor systems and algorithms on a high bypass turbofan engine under the following conditions: (1) Normal engine operations; (2) Seeded mechanical faults; (3) Seeded gas path faults; and (4) Accelerated engine life degradation through volcanic ash ingestion testing. The first VIPR test took place in December 2011 at NASA Dryden Flight Center/Edwards Air Force Base as an on-wing ground test on a heavily instrumented high bypass turbofan engine. This test featured: 1. Emission Sensor System: Investigation of the ability of of an array of chemical sensors to detect a simulated oil leak and measure changes in sensor response with changing engine conditions.2. Self Diagnostic Accelerometer feasibility test: Demonstrate operability of self-diagnostic accelerometer in aircraft engine environment3. Validate Gas Path Diagnostics: Test analytical model predictions of engine parameters in the presence of bleed valve faults (failed, full open; schedule bias) An unique feature of this VIPR series is an upcoming test, which includes the planned ingestion of volcanic ash into an engine on-board an aircraft. The primary objectives of this work are to determine the effect on the engine of several hours of exposure to low to moderate ash concentrations and to evaluate the capability of engine health management technologies for detecting these effects. Numerous observations and measurements of the engine’s performance and degradation will be made during the course of the experiment. While not intended to be sufficient for rigorous certification of engine performance when ash is ingested, the experiment should provide useful information to aircraft manufacturers, airline operators, and military and civil regulators in their efforts to evaluate the range of risks that ash hazards pose to aviation. A research team of U.S. Government agencies and engine manufacturers are involved in this VIPR testing. This government and industry partnership is not only crucial in enabling the tests, but is also a method by which various organizations can be involved in the demonstration and maturation of technologies, facilitating potential future acceptance. A conclusion of this paper is that partnerships between developers and users of new technologies are crucial towards enabling technology commercialization and acceptance. Not only does this type of work allow the ability to mature and evaluate the technologies in environments reflective of potential application, interaction with potential technology users can provide feedback on pathways towards technology improvements and possible implementation.

Software Framework for Prototyping Embedded Integrated Vehicle Health Management Applications

Integrated vehicle health management is a major component in a new, future fleet-management paradigm where a conscious effort is made to shift aircraft maintenance from a schedule-based approach to a more proactive and predictive approach (that is, condition-based maintenance). Its goal is to maximize fleet operational availability while minimizing the logistics footprint through monitoring of the deterioration of equipment conditions. A comprehensive integrated vehicle health-management system will be executed in an environment that includes different sensor technologies, multiple information systems, and different data models. Integrated vehicle healthmanagement implementers have to therefore deal with an integration problem that involves different specialized algorithms and embedded hardware platforms. Integrated vehicle health management applications will have common execution logic, and many will share the same data-processing algorithms; hence, development productivity and the quality of integrated vehicle health management applications can be increased through reusable software building blocks and algorithm libraries or, in particular, by using a software development framework. This paper presents an approach to distributed integrated vehicle health management systems that offers reusable software architecture for a class of integrated vehicle health management applications. The focus of this paper deals with an open software framework for development of integrated vehicle health management applications stemming from the open system architecture for a condition-based maintenance specification, which is an architecture-promoting interoperability and a component framework that enables reuse, data-process partitioning, configuration, and rapid prototyping. The framework is developed using Java and Internet communications engines’ distributed middleware, and its application is demonstrated through a gearbox health-monitoring system, where the integrated vehicle health management software is deployed on the distributed embedded devices. This approach provides software-enabled capability to distribute/reconfigure the integrated vehicle health management data process (through the open system architecture for condition-based maintenance common interface and data model) across the hardware platforms to meet the given system configuration. The performance evaluation for the test example shows negligible overhead in the central processing unit, bandwidth, and latency when using the framework.

Rotordynamic Faults: Recent Advances in Diagnosis and Prognosis

Diagnosis and condition monitoring in rotating machinery has been a subject of intense research for the last century. Recent developments indicate the drive towards integration of diagnosis and prognosis algorithms in future integrated vehicle health management (IVHM) systems. With this in mind, this paper concentrates on highlighting some of the latest research on common faults in rotating machines. Eight key faults have been described; the selected faults include unbalance, misalignment, rub/looseness, fluid-induced instability, bearing failure, shaft cracks, blade cracks, and shaft bow. Each of these faults has been detailed with regard to sensors, fault identification techniques, localization, prognosis, and modeling. The intent of the paper is to highlight the latest technologies pioneering the drive towards next-generation IVHM systems for rotating machinery.

Integrating nondestructive inspections with autonomic logistics and structural health monitoring strategies for aeronautic systems

In recent years, there has been much activity concerning health management of aviation systems. Many government- and industry-based research projects/programs are focused on integrated vehicle health management strategies that include sensor development for automated or manual fault detection, diagnostics, prognostics to define remaining useful life, as well as mitigation plans for continued safe operation during a fault. The overall objectives for such activities include increased safety as well as efficient and economic operation of an aircraft fleet. Currently, to assess structural faults, visual inspections and/or nondestructive inspection techniques are utilized as a required routine for certain design and life management strategies. The inspections are manually involved and are carried out during aircraft downtime (e.g. on the runway or nightly hangar maintenance) or during a more extensive aircraft overhaul. Even with the potential of automated structural health monitoring within an integrated vehicle health management system, it is foreseen that manual and nondestructive inspections will continue to be an integral part of fleet life management. This article addresses and clarifies the role of nondestructive inspections in aircraft life management and its potential inclusion in future integrated vehicle health management systems.

Integrated Vehicle Health Management and Unmanned Aviation

Over the past decade the use of unmanned aerial systems (UAS) has increased in military, intelligence, and surveillance operations for dull, dirty and dangerous (DDD) missions. They have primarily been used at a time of war, and been pushed into service by programmes designed increase the capabilities of military organisations, with little thought of supportability or interaction with other air users. The increased use of UAS in war time and the ensuing media coverage has naturally led proposed use of UAS in a civilian context, being used for a wide range of non-militaryDDD missions: from land usage and crop monitoring; to the monitoring of nuclear power plants; to inspection of power lines.But when considering the use of UAS this civilian context brings up important issues, such as: How can UAS be integrated into civil unsegregated airspace, and how will they react to other air traffic (manned and unmanned)? How can UAS be shown to be safe to get general public, especial with an increased level of autonomy? What technologies are needed to ensure the safe use of UAS? Is using a UAS more economical than using the manned equivalent? The list goes on.Steps have already been taken to answer these issues, in the United Kingdom the Civil Aviation Authority (CAA) have produced guidance (CAP 722) for manufactures and operators of UAS, to allow them to build and operate UAS whilst developing a framework to fully integrate them into the civil airspace. In addition the CAA is working closely with industry-led consortium ASTRAEA (Autonomous Systems Technology Related Airborne Evaluation & Assessment) to help solve the issues of using UAS in civil airspace, and with the United States Federal Aviation Administration (FAA) having been set a 2015 deadline for full integration, hastening the need for solutions to be found. The poster will take a holistic systems engineering view of the current situation in unmanned aviation and where Integrated Vehicle Health Management (IVHM) might be used (in whole or in part) to solve some of the issues mentioned above.It will present reasons why you may wish to include IVHM in a UAS (e.g. cost, size, safety), the potential benefits (e.g. increased availability, reduced maintenance costs) and pitfalls (e.g. false positives) of implementing an IVHM on a UAS. It will also map how the IVHM (system of interest) interacts with the rest of the UAS (wider system of interest), how it relates to the issues the aviation industry have with UAS (environment) and the general public (wider environment).

Autonomous safety and reliability features of the K-1 avionics system

Kistler Aerospace Corporation is developing the K-1, a fully reusable, two-stage-to-orbit launch vehicle. Both stages return to the launch site using parachutes and airbags. Initial flight operations will occur from Woomera, Australia. K-1 guidance is performed autonomously. Each stage of the K-1 employs a triplex, fault tolerant avionics architecture, including three fault tolerant computers and three radiation hardened Embedded GPS/INS units with a hardware voter. The K-1 has an Integrated Vehicle Health Management (IVHM) system on each stage residing in the three vehicle computers based on similar systems in commercial aircraft. During first-stage ascent, the IVHM system performs an Instantaneous Impact Prediction (IIP) calculation 25 times per second, initiating an abort in the event the vehicle is outside a predetermined safety corridor for at least 3 consecutive calculations. In this event, commands are issued to terminate thrust, separate the stages, dump all propellant in the first-stage, and initiate a normal landing sequence. The second-stage flight computer calculates its ability to reach orbit along its state vector, initiating an abort sequence similar to the first stage if it cannot. On a nominal mission, following separation, the second-stage also performs calculations to assure its impact point is within a safety corridor. The K-1's guidance and control design is being tested through simulation with hardware-in-the-loop at Draper Laboratory. Kistler's verification strategy assures reliable and safe operation of the K-1.