Browse Topic: Maintainability and supportability
Rolling-element bearings in rotorcraft dynamic systems are critical components susceptible to rolling contact fatigue (RCF), a dominant degradation mechanism manifesting through subsurface-initiated spalling, surface micropitting, and fatigue fractures. Robust inspection strategies compliant with EASA and FAA requirements are therefore essential. Traditional methods are often invasive, requiring disassembly, and are susceptible to human-factor errors. Smart Duplex introduces a design-for-monitoring architecture integrating in-situ videoscopic and coherence scanning interferometry (CSI) for high-resolution 3D surface mapping, including under partial grease coverage. This paper details a repeatability and reproducibility (R&R) framework ensuring metric consistency; a maintainability assessment projecting significant man-hour reductions and high availability; certification rationale emphasizing airworthiness improvements via enhanced detectability, workload reduction, and digitized inspection records; and an airworthiness mapping supporting threat assessments, Airworthiness Limitations Section (ALS) entries, and usage-based maintenance credits. By embedding sensing capability and digitizing inspection records, Smart Duplex minimizes downtime, mitigates human-factor errors, and facilitates predictive maintenance, optimizing cost, enhancing performance, and ultimately improving safety.
This paper describes the characteristics of the Leonardo Advanced Tiltrotor Aircraft (ATA) concept, focusing on the relationship between goals, targeted improvements and enabling design features. The paper shows the design drivers such as performance, operational capabilities, and maneuverability and it describes how the attributes of the concept originated, showing trade-off and compromises approached during the genesis of the concept. The design drivers are translated into areas of interests, including download, drag, aerodynamic efficiency, rolling and yawing inertia, detectability, maintainability and engine retrofit ability. Finally, these areas are linked to the physical features of the concept, showing how they have been selected and combined to achieve the best overall benefit at platform level.
The power of advanced driver assistance systems (ADAS) continues to increase alongside vehicle code and software complexity. To ensure ADAS functionality and maximize safety, cost efficiency, and customer satisfaction, original equipment manufacturers (OEMs) must adopt a solution that allows them to mine data, extract meaningful information, send remote software updates and bug fixes, and manage software complexity. All of this is possible with an embedded telematics-based software and data management solution. Event-based logging enables OEMs to actively measure ADAS effectiveness and performance. It allows them to analyze driver behaviors, such as whether response times increase after a certain time of day, and adjust the ADAS settings to increase functionality, such as providing an earlier warning or automated response. A vertically integrated solution also enables the identification and correction of software and calibration defects for the entire vehicle life cycle through over-the-air (OTA) software update packages. This eliminates the need for costly and time-consuming dealer visits and allows troubleshooting, updates, repairs, and recalibration to be performed remotely. There are industry-wide benefits of deep connectivity as well, such as the sharing of critical and safety-related data to make functional enhancements and use in the creation of a real-world safety rating system instead of one based on lab data and general speculation. Connected services are essential for not only the future of ADAS but also for the creation of a safer driving environment for all. In this paper we will: Look at emerging trends in ADAS vehicle systems Show how connected vehicle data can measure real-world ADAS performance, including false positives and false negatives Show how connected vehicle data can be used to understand driver behaviors including usage patterns and feedback responsiveness Show how systems can be maintained and enhanced throughout the product life cycle in a cost-effective manner
ABSTRACT A toolchain must be functionally cohesive with a business process, especially in technical domains such as complex systems engineering. Despite the industry-wide shift towards model-based digitization within engineering organizations, there is a lack of development in implementing model-based RAMS (Reliability, Availability, Maintenance, Safety) processes. This results in a missed opportunity to create value throughout the entire system lifecycle, from conceptual design to operations. This paper proposes some reasons for this and outlines a framework for evaluating model-based toolchains in the context of the entire Engineering cycle. A model-based architecture for RAMS is proposed and contrastively evaluated with respect to SysML. Key use cases are identified, and benefits are demonstrated using Maintenance Aware Design Environment Software. Citation: J. Langton, S. Hilton, “Iterative Co-Design Of Organizational Processes and Toolchains For Model-Based Reliability, Availability Maintainability and Safety Integration,” In Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium (GVSETS), NDIA, Novi, MI, Aug. 16-18, 2022.
In industry, and more particularly in the aviation maintenance industry, Human Factors/Ergonomics (HFE) is increasingly considered by maintainability stakeholders in the aircraft development process. However, most of the stakeholders are not specialized in HFE, therefore the compromise between HFE and design criteria is not optimized. This paper introduces a methodology proposal to enhance integration of HFE in aviation maintenance by maintainability stakeholders without HFE skills and knowledge. This methodology, called PEAM (Preliminary Ergonomics Analysis in Maintainability) will not replace the HFE specialist but will help all maintainability stakeholders to anticipate the maintenance operator's activity in the preliminary phases of aircraft design. This paper will also introduce the first results regarding PEAM deployment efficiency.
The Model-Based Development (MBD) paradigm is widely used for embedded controls development, with the MathWorks Simulink modelling environment being extensively used in the automotive industry. As production-scale Simulink models are typically large and complex, there exists a need to decompose them properly in order to facilitate their maintainability, understandability, and evolution. MathWorks recommends the use of three constructs for model “componentization” or decomposition: the Subsystem, Library, and Model Reference. However, a recently added construct introduced in Simulink R2014b, the Simulink Function, can also be used for this purpose, while also supporting information hiding due to the construct’s ability to be scoped and encapsulate data. This paper provides an in-depth comparison of these Simulink constructs to fully understand the differences in their reusability, sharing of program state, encapsulation, and code generation, with the goal of facilitating model evolution. An automotive powertrain example is provided to highlight the differences between approaches. Conventions for structuring models are also presented.
ABSTRACT Reliability Physics simulations for electronic assemblies has matured to become best practice during specification and design. However, the potential advantages of these simulations to programs and integrators are more far reaching. This paper will explore how the simulations can be used for virtual qualification, reliability assurance, maintenance scheduling and obsolescence management. Citation: Ed Dodd, “Reliability Simulations for Electronic Assemblies: Virtual Qualification, Reliability Assurance, Maintenance Scheduling and Obsolescence Mitigation”, In Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium (GVSETS), NDIA, Novi, MI, Aug. 13-15, 2019.
As the U.S. Army endeavors to maintain overmatch capability in the global arena, Future Vertical Lift has become a high priority. In a climate that demands a more efficient and affordable acquisition process, it is imperative that structural integrity requirements are maintained as a priority to ensure initial quality, supportability, and maintainability considerations. Therefore, it is paramount that a standard practice be utilized so that structural integrity requirements are clearly understood by the Product Office, the Airworthiness Authority, and the Original Equipment Manufacturer(s). This paper highlights how the MIL-STD-3063 U.S. Army Standard Practice for Rotorcraft Structural Integrity Programs can meet these demands by laying out interrelated functional tasks in a concise manner to allow for decision makers to make sound choices with regards to structural integrity for any new developmental aircraft. The paper also details how the standard practice is being utilized to assist and guide Future Vertical Lift efforts.
ABSTRACT In order to assess a design from a supportability perspective early in a technology’s prototyping phase, TARDEC’s Systems Engineering Directorate has established a Design for Supportability (DfS) competency. This competency, under the SE umbrella, encompasses the relationship between Design for Reliability (DfR), Design for Maintainability (DfM), and Design for Logistics (DfL). The combination of DfR, DfM and DfL form a trifecta of knowledge that determines whether a developing technology will: 1) perform its intended function for the complete duration of the mission it’s designed for; 2) be designed in a way to be fixable in a reasonable amount of time using standard tools; 3) be designed to have replaceable parts as accessible as possible; 4) not increase the logistics burden for our men and women in uniform.
Four lasers can be used for micro welding: pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG), continuous wave (CW) fiber, quasi continuous wave (QCW) fiber, and nanosecond fiber. Each laser type offers unique features that work best for specific applications. Here is a comparison of the pulsed Nd:YAG laser with the three fiber laser options, and a discussion of why and when one might be chosen over the other. In some cases, several options may work; in that case, cost of ownership and serviceability can tip the scales.
Four lasers can be used for micro welding: pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG), continuous wave (CW) fiber, quasi continuous wave (QCW) fiber, and nanosecond fiber. Each laser type offers unique features that work best for specific applications. This article presents a comparison of the pulsed Nd:YAG laser with the three fiber laser options and discusses why and when one might be chosen over the other. In some cases, several options may work; in that case, cost of ownership and serviceability can tip the scales.
Operations and support cost constitutes nearly 70% of rotorcraft lifecycle cost. When considering new rotorcraft concepts and technology infusion for current concepts, quantitative performance evaluation is undertaken during conceptual design. However, the effect of design decisions on operations and support metrics are typically evaluated qualitatively. Since operation and support costs constitute an overwhelming majority of rotorcraft lifecycle cost, quantitative evaluation of these metrics is required to fully capture the design trade space. To this end, an integrated discrete-event simulation environment is developed to quantify the impact of architectural decisions and subsystem technology infusion on key metrics including the operational availability, system mean time between failures, Maintenance Free Operating Period, repair cost, and maintenance man-hours needed for a given period of operation. Since data needs are immense, it is appropriate to use data from existing platforms to populate unknown fields. An example is presented in this paper for a notional helicopter to demonstrate the use of the discrete-event simulation environment as a tradeoff environment for operations and supportability metrics.
Advanced composite materials are disrupting incumbent metallic materials in Army Aviation and creating new value networks that span the supply chain from raw material manufacturers to specialty equipment for sustainment of composite structures. In order to prepare Army Aviation for fielding and supporting an all-composite aircraft, many investment decisions need to be made today to facilitate the influx of training, tools, materials, and processes that will be necessary. This whitepaper walks through the defense acquisition lifecycle and discusses considerations for supportability of these advanced composite structures at each phase. Multiple case studies are presented to highlight opportunities to help inform the leaders and managers that are making the investment decisions now for tomorrow's weapon systems.
This paper discusses key enablers of a substantiation process that can support both the structural integrity and maintainability goals for either existing or new platforms as they are upgraded with complex systems or other emerging technologies. A new approach to substantiate and maintain rotorcraft structural integrity throughout the operational life cycle can be acquired through the Structural Usage Monitoring System (SUMS) tools employed for Condition-based Maintenance (CBM) systems, with the load monitoring and estimation functionality viewed as a key enabler for the substantiation process. The decision-makers trade space is briefly discussed in this paper, and an example is provided for illustration.
A Development Assurance Value-Based Acquisition (DAVBA) Model To Address Identified Current Systems Engineering Topics of Particular Interest.This AHS Technical Specialists' Meeting announcement has identified current topics of particular interest. They include, but are not limited to: Capability versus affordability ; Managing cost and schedule risk in a volatile defense budget; Technology insertion timeline versus user needs; Consideration of safety, reliability, manufacturing and supportability requirements early in the requirement negotiating process. A systems engineering approach that develops a Development Assurance Value Based Acquisition (DAVBA) model can be used to address all four of these topics.
Many of the “ilities” (Reliability, Maintainability, etc) are afterthoughts in the creation of a specification, and are often relegated to a set of templated boilerplate requirements, that are largely ignored. The Reliability / Robust Design professionals often use a P-Diagram (Parameter Diagram) as a key part of understanding the system under design. A way of integrating the Reliability effort more into the mainstream of the design activity, and give them a stronger voice, is to put their P-Diagram right into the specification, before it gets released to industry. This paper describes the rationale and the manner in which to do this.
This seal features dual sealing capabilities: a face seal and an axial seal. The name swan seal is derived from its cross section, which resembles a swan. Most injector designs require fuel to be delivered from an inlet fitting, through a feed arm, to the injector tip. Temperature variation from the inlet to the tip, from the cool fuel to hot combustion air, and from startup to full power, often poses a challenge due to thermal growth. One of the most challenging areas is accommodating the growth differential between a hot feed arm and a cool fuel delivery tube, which is exacerbated by the relatively long distance. Several methods have been used to allow for this including coiling the fuel tube, utilizing an O-ring sliding seal, metal C-seals, or incorporating stretchable bellows. Some of the drawbacks of these methods include limited space, poor durability at high temperatures, serviceability, long lead times, and cost. The swan seal presents a compact, high-temperature, replaceable, low-cost option for this and other applications where a sliding axial seal is required.
ABSTRACT Due to its subjective nature, the concept of value is not one that is easily defined. Marketers often refer to a product's 'value proposition' as an explanation to why an operator should buy a product or use a service. This statement should convince a potential operator that one particular product or service will add more value or better solve a problem than other similar offerings. In the rotorcraft market, this value proposition is often tied to capabilities of the helicopter and is typically defined as a composite metric. This metric is then compared to the acquisition cost to get a sense of helicopter value. Helicopter manufacturer's marketing and sales departments then go to the market and sell the benefits, either in range, take-off weight, reliability, operating cost, etc… One major difference in the value stream of rotorcraft products as compared to typical consumer products is that it is standard for a second-level supplier, in this case the engine manufacturer, to offer its own services and support. This creates an environment where both the helicopter and engine manufacturer have direct contact with the end operator and can influence their perception of value. A method for an engine manufacturer to define value can aid the helicopter manufacturer, and ultimately, the operator, to make an informed decision regarding the right product for their mission objectives. In order to derive a metric for the concept of value for a helicopter engine, one must understand the important aspects from an operational perspective, as opposed to the technical focus typically associated to this type of product. This paper focuses on the derivation of such a composite metric by using terms that represent a product's reliability, maintainability, and capability as compared to its direct operating cost as the acquisition cost of the engine is transparent to the end operator. Looking at the helicopter engine competitive environment in such a way serves two purposes: one for the engine manufacturer to be able to gauge the competitiveness of their product, and one for the operators to understand an engine's value proposition and how it fits into the helicopter capabilities. The details of how the metric of engine productivity were derived will not be elaborated as they are considered intellectual property to Pratt and Whitney Canada, but the benefits and concepts of viewing helicopter engines in such a way can be discussed.
The development work to date of a generalized cost model which integrates operating costs, reliability and maintainability into rotorcraft conceptual design is described. The cost model is combined with a rotorcraft sizing code to predict the flyaway and O&S cost impacts of varying design mission payload and range. For a fixed mission range, scaling an example aircraft from 14 to 18 passengers is shown to have a favorable impact of up to 14% reduction in direct operating cost per available seat-mile. Trends in maintenance costs are explored, suggesting that measures representative of best practice maintenance may reduce total operating costs per available seat-mile by as much as 20% through a combination of reduced cost per maintenance action and reduced aircraft maintenance down time. Reliability is further investigated by using the code to calculate the fleet impact of operational availability requirements on fleet size and fixed annual costs. Future work is suggested in the context of using reliability and maintainability issues to better guide rotorcraft conceptual design.
This SAE Standard defines the basic structural elements, and guidance on compilation and management, for a software supportability program. Software supportability considerations include initial design influence and through-life support embracing the operational use, post-delivery modification, and logistics management of software. This document requires that the processes of design, development, selection, and production of software include software supportability considerations, as relevant to particular project needs.
Current Army aviation maintenance is reactive to faults, not proactive, resulting in an excessive logistics support burden and high operations and sustainment (O&S) costs. One of the Army's science and technology goals is to mature and transition advanced technologies to enable condition-based maintenance (CBM). In 2007, the US Army Aviation Applied Technology Directorate (AATD) initiated a program with Bell Helicopter to develop and demonstrate an integrated set of diagnostic, prognostic, and system health assessment technologies to support Army objectives and enable transition to a condition-based maintenance philosophy. Specifically, the program developed an integrated set of technologies to enable reduction of inspections and preventative maintenance; expansion of serviceability criteria; extension of life or time between overhaul; and prediction of failure with sufficient fidelity to allow scheduling of maintenance. This paper will provide an overview of the program results.
This document provides information to help the reader view maintainability in the context of an overall systems engineering effort. The guide defines maintainability, describes its relationship to other disciplines, addresses the basic elements common to sound maintainability programs, and describes the tasks and activities associated with those elements.
One of the most expensive and time consuming tasks relating to Condition Based Maintenance involves the testing of mechanical components for CBM. A scientific plan is being developed to identify components that will return the most value within a short time for implementation of CBM. This plan is also based on the historical (TAMMS-A and VMU) data that we have collected and analyzed throughout the past eight years. This paper specifically addresses the component mapping methodologies and the USC CBM test facilities. Furthermore, the CBM testing approach is discussed. The goal of testing is to identify the root causes of components' failure, failure modes and the identification of ways to improve serviceability of A/C components. Components testing will be carried out for used but serviceable components or with components with intentionally seeded faults. Some component test results are presented and discussed.
Helicopter Health and Usage Monitoring Systems (HUMS) provide many benefits, one of which is the ability to provide real time condition of aircraft systems on-board. Providing the aircraft pilot with pending failure information increases safety and in most cases affords the pilot ample time to perform safe precautionary landings. The information displayed to the pilot must be specific as to the system affected to allow for an immediate, intelligent assessment of the aircraft condition. The predominant challenge facing system engineering is establishing parameter and signal validity prior to generating parameter exceedance alarms. Data fidelity must be carefully considered and accomplished in every aspect prior to generating onboard alarms. The United States Marine Corp CH- 46E aircraft program has installed over 130 Honeywell Aircraft Integrated Maintenance Systems (AIMS), which provides a method of providing onboard alarming in three categories. (1) Non-Abort, post flight maintenance required, (2) Pilot informational displayed on the Control Display Navigation Unit, (3) Master Caution panel illumination for flight abort alarms. These three alarm categories represent the best approach to providing aircrew and maintenance personnel with system critical information for continued safe operation of the aircraft while performing maintenance in a field environment. The AIMS’ current configuration has over 100 alarms programmed for cockpit display if advisory criteria are valid. System architecture requires several faulting and alarming mechanisms working together to ensure data fidelity has been met prior to generating an alarm. Several techniques are employed to validate incoming engine parameter signals, such as range checking and rate of change qualification. If signals do not pass validity, alarming is suppressed. Vibration alarming is slightly different. The alarming mechanism utilized is a time hysteresis method, which employs a band alarm with an amplitude and time duration trigger, as well as an amplitude and time duration release. If validity fails, the alarming is suppressed. The Safety aspects are obvious; however just as significant are the maintenance savings recognized from reduction of component collateral damage. . With the belief that all pilots need to know the condition of the machine they are flying at all times, on-board alarming of critical flight components is a necessary function of HUMS. Condition based maintenance starts with safe landing of the aircraft without mishap. On-board alarming will provide increased safety, reliability, and maintainability for the fleet. Savings are incalculable as prevention of the mishap is pricele
Today, the troubleshooting process for gas turbine engines, coupled electrical systems and sub-systems installed on military helicopters is both burdensome and error prone. Maintainers are required to follow static fault isolation procedures (i.e., fault trees), either paper or electronic, that detail a series of sequential test and repair steps. There is a lack of direct communication between embedded (on-board) fault diagnostics and ground based troubleshooting systems, which necessitates transferring information manually that could otherwise be attained digitally and without human error. Today, troubleshooting effectiveness is, at best, on the order of 50%. Removed components are often categorized as No Evidence of Failure (NEOF) when tested in the back shops and Reliability and Maintainability (R&M) data associated with the maintenance tasks is not easily accessible.
This document provides information to help the reader view maintainability in the context of an overall systems engineering effort. The guide defines maintainability, describes its relationship to other disciplines, addresses the basic elements common to sound maintainability programs, and describes the tasks and activities associated with those elements.
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