Browse Topic: Maintenance, repair and overhaul (MRO)
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The operation of Urban Air Mobility Vehicles (UAMVs) presents significant technical and operational challenges, particularly in the areas of safety, training, and cost management. This paper explores how advanced simulation models and predictive algorithms can address these challenges. A digital transformation framework is developed and applied in an Urban Air Mobility (UAM) case study to illustrate the effectiveness of these tools. Through the development of simulation models, critical insights are provided on damage detection, impact analysis, and maintenance optimization. The application of predictive algorithms enables quick damage assessment, improving safety by facilitating timely maintenance and repair decisions. To help showcase the benefits of this research, a demonstration was designed and built that allows users to interact with the developed tools and get a better understanding through hands-on training.
Electrification could improve full-size rotorcraft performance by reducing peak turbine power demand, reducing transmission system weight and complexity, and reducing operating costs. Integrating electric machines with mechanical powertrains requires careful consideration of the system-level weight and efficiency impacts. This paper presents an optimization framework for evaluating parallel hybrid powertrain configurations using Geometric Programming (GP). Both retrofit and clean-sheet vehicle designs are considered. The results show that high-speed electric motors integrated into a parallel hybrid configuration using batteries can reduce the sized gas turbine power, enabling more efficient engine operation at lower power levels. For retrofit designs, with a fixed vehicle gross weight, adding batteries and motors reduces usable fuel, decreasing mission capability. Clean-sheet designs offer additional flexibility to re-size the vehicle and rotor, resulting in energy savings for an equivalent design mission.
As part of a human factors research project aimed at optimizing technical documentation used in helicopter maintenance with multimedia elements, we compared different instruction formats to observe their effects on the performance of an assembly task. This task offers us the opportunity to test procedures that call for similar actions as a maintenance task (e.g., localization, action sequencing, assembly). Static (i.e., image and image with text) and dynamic instruction formats (i.e., video, video with text and video with audio) were compared to determine if dynamic formats allowed a better motor performance of the task for assembly reaction time (time needed to complete the assembly) and accuracy. We were also interested in how the use of the text instructions interacted with both visual dynamic and static instructions. Reaction times were recorded and measured with eye tracking data. Subjective data was collected in questionnaires during and after the experiment. Results showed significant differences in the time spent on the instructions and the time spent on the assembly, depending on the format of instructions. Overall, assembly time is shorter with video instruction formats, but videos took longer to be consulted than static formats. Results also showed a difference in the number of actions required to do the assembly. Videos facilitated the right path of action sequence in comparison with static formats. With the analysis of both subjective and objective data, the results give us a better idea of the advantages and drawbacks of using dynamic formats in technical documentation.
Aircraft Certification is a mature and complex bureaucracy that has successfully ensured a very high degree of safety of aircraft design, construction, operation and maintenance. Outside of a very few doing the work, there is a general lack of knowledge of certification details. For novel technologies such as electric power, and innovative configurations such as multi-rotors, the rules are far less mature and still emerging and so also poorly understood. Within the Advanced Air Mobility (AAM) initiative, many new aircraft developments are underway using novel configurations, and the public announcements of regulatory progress toward FAA or EASA Type Certification capitalize on this ignorance by being vague or even misleading. Honeywell conceived the Regulatory Readiness Level (RRL) indicator as an objective measure of certification status to serve the AAM industry and ecosystem, with applicability across aviation. The released RRL Version 1 now enables credible, objective assessment of new aircraft progress toward FAA Type Certification, and Operational Approval for Part 135 operations, to allow consistent apples-to-apples comparisons with other aircraft in development. An emerging complementary version of the rubric for EASA Type Certification is ready for publication to enable RRL determination against the European Union criteria. Future releases will consider other Nation's regulatory authorities, supplemental types certifications (STCs), and risk-based airworthiness assessments such as the Specific Operations Risk Assessments (SORA).
Wear debris monitoring and analysis is a common practice for the condition assessment of engine and transmission health. Oil debris monitoring (ODM) and electronic chip detectors (ECD) are two common methods deployed for continuous monitoring of oil wetted component health in-flight. This study evaluates the diagnostic performance of the two sensing technologies within controlled rolling element bearing (REB) fault experiments. Progressive visual inspection of the REB spall progression through failure provided a ground truth against which both systems could be compared. Quantifiable metrics of reliability, diagnostic accuracy, provided maintenance interval were defined to create a framework for condition-based maintenance (CBM) program decision making. In summary, it was found that the ODM sensor system provided earlier fault notice, but more so, vastly outperformed the ECD in reliability and avoidance of false positives.
The DoD enterprise requires a blueprint for each service and industry base to develop, integrate, and connect crewed and uncrewed platforms across the aviation and ground domains to satisfy the goals of programs such as Replicator, Human Machine Integrated Formation (HMIF) and Joint All Domain Command and Control (JADC2) as a whole. Thanks to years of architecture work by Program Executive Office (PEO) Aviation, PEO Ground Control System (GCS), and the Ground Vehicle Services Center (GVSC), the necessary open standards-based reference architectures, objective architectures, Major System Components (MSCs), and Major System Interfaces (MSIs) can be leveraged to create an executable plan for the Army, the DoD, and the international community as a whole. This paper proposes how to leverage government-owned elements across multiple Army offices to provide a Modular Open Systems Approach (MOSA) that achieves the speed, portability, and interoperability of capabilities needed for the conflicts of tomorrow.
Maintenance of spatial orientation (SO) is achieved primarily through visual information where the horizon and celestial reference cues or flight instruments are used by pilots to infer aircraft orientation. However, cross checking the instruments in degraded visual environments can be complicated by factors such as workload, distraction, and situations where the vestibular and proprioceptive systems may provide false and competing orientation information. We describe experiments measuring pilot performance using a flight simulator under challenging conditions where the sensory information was controlled. Reducing available visual instruments increased the task difficulty. A wearable vibrotactile array could provide concurrent, additional orientation information. Increasing the flying task segment difficulty increased the perceived workload and also corresponded to an increase in accidents. Adding tactile orientation information reduced the accident rate.
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The aerospace ecosystem is a complex system of systems comprising of many stakeholders in exchanging technical, design, development, certification, operational, and maintenance data across the different lifecycle stages of an aircraft from concept, engineering, manufacturing, operations, and maintenance to its disposal. Many standards have been developed to standardize and improve the effectiveness, efficiency, and security of the data transfer processes in the aerospace ecosystem. There are still challenges in data transfer due to the lack of standards in certain areas and lack of awareness and implementation of some standards. G-31 standards committee of SAE International has conducted a study on the available digital data standards in aircraft asset life cycle to understand the current and future landscapes of the needed digital data standards and identify gaps. This technical paper presents the study conducted by the G-31 technical committee. This paper reviews the data being exchanged between various stakeholders in the aerospace asset lifecycle and the availability of standards for the data transfer within the aerospace ecosystem. It identifies gaps based on the list of currently available data standards, and then creates a future landscape to address the needed digital data standards. This paper focuses on aircraft operations, maintenance, transfer, disposal processes, and post-build stage, and does not address the detailed interactions during the aircraft design, development and manufacturing phases. Its scope is also limited to key stakeholder interactions throughout the different stages of the aircraft operations, maintenance, and retirement.
Over the last decade or more there has been a concerted push to move from on condition to predictive maintenance to improve rotorcraft availability and cost competitiveness of sustainment (Ref. 1-2). The US Army, along with industry partners, have been working on the development of prognostics for complete rotorcraft coverage. It has been identified that accurately capturing maintenance actions is needed to improve the accuracy of prognostics for better component health state awareness. Further to achieve the Army's vision for Zero Maintenance rotorcraft and meet the Maintenance Free Operating Period (MFOP) (Ref. 3) requirements for the Future Vertical Lift (FVL) program, it's essential to have an automated configuration management system. To help meet these objectives, the Army and Honeywell are working on the Rotorcraft Automated Component Tracking (RACT) Science and Technology (S&T) development program. This paper discusses the research being conducted to enable the Army's RACT concept done by the Honeywell team and the CCDC AvMC. It identifies the current state of RACT technologies and challenges of integrating such technologies into the rotorcraft environment.
The U.S. Department of Defense has begun the acquisition of the next generation of military rotorcraft, named Future Vertical Lift (FVL), to replace its aging fleet. U.S. Army Futures Command intends to sustain FVL under a new strategy of maintenance free operating periods (MFOP). This study developed a discrete event simulation to evaluate MFOP success given component reliabilities, desired MFOP duration, and operational tempo of a battalion with thirty aircraft. The simulation compared notional FVL aircraft with improved reliability to today's fleet. Results indicated that inherent reliability alone was insufficient to achieve MFOP goals and that prognostics and diagnostics with robust information management are necessary. Sensitivity studies found the recovery effort after an MFOP was linked to the MFOP duration. Recovery downtime was tied to both the duration and operational tempo. Availability and cost improved with moderate gains in MFOP duration by eliminating unnecessary preventive maintenance but overextending the MFOP sacrificed aircraft dependability for marginally greater availability and savings.
Weight and balance activities are widely recognized and understood as important steps in the operation and maintenance of an aircraft to ensure safe and efficient flight. From the pilot's perspective, the operational limits and maneuverability of the aircraft are directly linked to the weight and balance of the aircraft. From a structural perspective, fatigue damage can vary significantly with center of gravity position and gross weight. In-flight center of gravity and gross weight estimation has been pursued for many years with varying success. One of the major challenges is the lack of data to verify an estimation model, since these parameters cannot be easily measured using sensors in flight. This paper reviews in detail the requirement and challenges of accurately monitoring center of gravity and gross weight. In addition, a survey of published work on the estimation of these values is provided. These efforts are divided into four categories: helicopter dynamic models, performance charts, state estimation, and machine learning methods.
Purpose of this paper is to describe the new approach for the analysis of Health and Usage data implemented by Heliwise, a software tool developed by Leonardo Helicopters, and aimed to increase the aircraft availability (with reduction of unexpected Aircraft On Ground's) and to minimize the extraordinary maintenance activities. In this paper will be shown how Heliwise can achieve this result by implementing an architecture which is modular, flexible and suitable to operate in a global environment, a sort of HUMS technical community, where all data are shared.
The Autonomous Sustainment Technologies for Rotorcraft Operations-Structures (ASTRO-S) project between U. S. Army Combat Capability Missile Center, Aviation Development Directorate-Eustis (FCDD-AMV-E) and Sikorsky developed and validated a range of technologies to enable reduced airframe maintenance burden, increase operational availability, and provide key enabling technologies relative to Army's transition to the new paradigm of Maintenance Free Operational Periods (MFOP) for the rotorcraft of the future. Methods were developed for autonomous characterization of major damage and residual strength expressed as a Structural Health Index (SHI) for advanced durable and damage tolerant composite aerospace structural assemblies with redundant load paths, enabling targeted inspections and strength-based fly / watch / repair decisions. A number of sensing technologies including fiber-optic strain measurement and piezo-based structural health assessment, along with a number of innovative advanced algorithms that intelligently use changes in monitored structural responses, were implemented in a comprehensive architecture to detect, localize, and assess the severity of structural damage. Extensive testing on full-scale, multiload-path composite structures to assess feasibility and effectiveness of the developed technologies, as well as understand application and transition challenges, has convincingly shown that damage detection, localization, and severity assessment in an autonomous fashion is feasible. Further, it was shown that the concept of a trendable SHI to assess residual strength, is viable, although additional full-scale test cases are needed to further validate and mature the approach. Overall, these key findings affirm suitability of the technical approach and associated algorithms for reducing maintenance burden by triggering rather than scheduling inspections and potentially deferring repairs in high op-tempo environments. These structural health management technologies will be key enablers supporting Army's future rotorcraft when operating in an untethered multi-domain battle space.
The Improved Turbine Engine (ITE) Program, run by the US Army's Aviation Turbine Engine Project Office (ATE PO), has a multi-faceted Modular Open System Approach (MOSA) to reduce engine integration and sustainment costs, control schedule risks, and enable opportunities for future upgrades. The approach is an integrated business and technical strategy that employs a modular hardware and software design, leverages data rights, employs United States Government (USG) defined interfaces using consensus-based standards, and makes architectural decisions based on lifecycle intentions for maintenance, sustainment, and possible future competition.
The U.S. Army Combat Capabilities Development Command's (CCDC) Aviation Engineering Directorate's Maintenance Engineering Division provides maintenance engineering support to a variety of Army aircraft systems. The Maintenance Engineering Division has historically supported overhaul, repair and maintenance functions for Army rotary aircraft, but has recently unveiled an avenue of opportunity to support Army unmanned aircraft system platforms as well. The Army's leading unmanned system is the MQ-1C, more frequently referred to as the Gray Eagle. The Maintenance Engineering Division assumed sustainment support of this system post production and deployment phase in the program lifecycle and has had to overcome several obstacles in that process. Even though the Army has provided sustainment support for rotary aircraft for several decades, unmanned aircraft programs in the Army are fairly new territory and a new path was paved to ensure similar sustainment support was provided. Forging this path has proved to be challenging since sustainment support was not well-defined early in the lifecycle even though approximately 70% of program costs are attributed to sustainment efforts on average. Consequently, engineers within the organization were challenged to pursue creative tactics to provide product support to unmanned aircraft in an equivalent manner to manned rotary aircraft, specifically for Gray Eagle Unmanned Aircraft System (UAS) in this report. The intent of this report is twofold; (1) inform the engineering community of the unique challenges of Gray Eagle UAS product support team, from a maintenance engineering perspective, and provide further insight into how they were overcome and (2) increase awareness in the acquisition community of the importance in considering sustainment/maintenance support early in the acquisition lifecycle to prevent technical barriers for a product support team with fielded systems.
U.S. involvement in the conflict in Southwest Asia has required prolonged deployment and field-level maintenance of hundreds of mission-critical Army aircraft. Theater settings present unique challenges for the U.S. Army and its aircraft maintainers, crews, and pilots alike. The U.S. Army Combat Capabilities Development Command Aviation and Missile Center deploys Liaison Engineers (LEs) to Southwest Asia in order to maintain airworthiness by delivering hands-on technical and logistical support to theater air crews and maintenance entities. This paper, with input from several previously deployed LEs, offers a look into the duties, responsibilities, and challenges of the LE in Southwest Asia.
Aging aircraft experience increased structural damage and failures as a result of corrosion. Detection of corrosion at its earliest stages is an important step toward improving aircraft readiness rates, safety, and reducing maintenance cost. We have developed and demonstrated a new Paint Additive/Non-destructive Interrogation (PANDI) system. The paint additive component is an innovative implementation of an inorganic nano-sized additive (INA) which was pursued to test for its ability to enhance the non-destructive interrogation system. Although it is shown herein to increase the transparency of the paint to PANDI's operational wavelengths of light when incorporated in a military paint system, the interrogation device was able to reach such a high sensitivity that no paint additive is needed for the system to effectively identify corrosion. The non-destructive interrogator is shown to measure absorption of light by hydroxyl ions accompanying the earliest formation of corrosion.
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