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This SAE Aerospace Information Report (AIR) reviews the precautions that must be taken and the corrections which must be evaluated and applied if the experimental error in measuring the temperature of a hot gas stream with a thermocouple is to be kept to a practicable minimum. Discussions will focus on Type K thermocouples, as defined in National Institute of Standards and Technology (NIST) Monograph 175 as Type K, nickel-chromium (Kp) alloy versus nickel-aluminium (Kn) alloy (or nickel-silicon alloy) thermocouples. However, the majority of the content is relevant to any thermocouple type used in gas turbine applications.

The purpose of this SAE Aerospace Information Report (AIR) is to present a quantitative approach for evaluating the performance and capabilities of an Engine Monitoring System (EMS).

ARP5120 provides recommended best practices, procedures, and technology to guide the physical and functional design, development, integration, verification, and validation of highly reliable Engine Health Management (EHM) systems for aircraft engines and Auxiliary Power Units (APUs). This SAE Aerospace Recommended Practice (ARP) also serves as a concise reference of considerations, approaches, activities, and requirements for producing the end-to-end engine health management system comprised of both on and off-board subsystems for the sensing, acquisition, analysis, detection, and data handling functions for EHM. These functions may also be used to effect continued operation or return to service decisions when demonstrated as compliant with the applicable airworthiness requirements defined by the responsible Aviation Authority. Where practical, this document delineates between military and commercial practices.

This document applies to prognostics of aerospace propulsion systems. Its purpose is to define the meaning of prognostics in this context, explain their potential and limitations, and to provide guidelines for potential approaches for use in existing condition monitoring environments. This document also includes some examples. The current revision does not provide specific guidance on validation and verification, nor does it address implementation aspects such as computational capability or certification.

This Aerospace Information Report (AIR) presents metrics for assessing the performance of diagnostic and prognostic algorithms and systems delivering propulsion health management functions.

This SAE Aerospace Recommended Practice (ARP) examines the whole construct of an Engine Health Management (EHM) system. This keystone document gives a top-level view and addresses EHM description, benefits, and capabilities, and provides examples. This ARP purposely addresses a wide range of EHM architectures to demonstrate possible EHM design options. This ARP is not intended as a legal document and does not provide detailed implementation steps, but does address general implementation concerns and potential benefits. Other SAE documents (Aerospace Standards, Aerospace Recommended Practices, and Aerospace Information Reports) address specific component specifications, procedures and "lessons learned".

This ARP provides an insight into how to approach a cost benefit analysis (CBA) to determine the return on investment (ROI) that would result from implementing a propulsion Prognostics and Health Management (PHM) system on an air vehicle. It describes the complexity of features that can be considered in the analysis, the different tools and approaches for conducting a CBA and differentiates between military and commercial applications. This document is intended to help those who might not necessarily have a deep technical understanding or familiarity with PHM systems but want to either quantify or understand the economic benefits (i.e., the value proposition) that a PHM system could provide.

The process detailed within this document is generic and can be applied to commercial and military applications. It applies to the entire end-to-end health management system throughout its lifecycle, covering on-board and on-ground elements. The practical application of this standardized process is detailed in the form of a checklist. The on-board element described here are the source of the data acquisition used for off-board analysis. The on-board aspects relating to safety of flight, pilot notification, etc., are addressed by the other SAE Committees standards and documents. This document does not prescribe hardware or software assurance levels, nor does it answer the question “how much mitigation and evidence are enough”. The criticality level and mitigation method will be determined between the ‘Applicant’ and the regulator.

The ice bath recommended herein is similar to that described in SAE AIR 46.* Some material not presented in AIR 46, including preferred dimensions, has been added.

This SAE Aerospace Recommended Practice (ARP) provides guidance for the design of flanges on temperature sensors intended for use in gas turbine engines. Three figures detail the configuration of standard size flange mounts with bolt holes, slotted flanges, and miniaturized flanges for small probes.

This SAE Aerospace Information Report (AIR) provides information and guidance for the selection and use of technologies and methods for lubrication system monitoring of gas turbine aircraft engines. This AIR describes technologies and methods covering oil system performance monitoring, oil debris monitoring, and oil condition monitoring. Both on-aircraft and off-aircraft applications are presented. A higher-level view of lubrication system monitoring as part of an overall engine monitoring system (EMS), is discussed in ARP1587. The scope of this document is limited to those lubrication system monitoring, inspection and analysis methods and devices that can be considered appropriate for health monitoring and routine maintenance. This AIR is intended to be used as a technical guide. It is not intended to be used as a legal document or standard.

SAE Aerospace Information Report AIR1871 provides valuable insight into lessons learned in the development, implementation, and operation of various health monitoring systems for propulsion engines and drive train systems. This document provides an overview of the lessons learned for ground-based systems, oil debris monitoring systems, lubrication systems, and Health and Usage Monitoring Systems (HUMS) for military and commercial programs. For each case study, this document presents a brief technical description, the design requirements, accomplishments, lessons learned, and future recommendations. The lessons learned presented in this document represent a fragment of the knowledge gained through experience when developing and implementing a propulsion health management system. Previous versions of this document contain additional lessons learned during the 1980’s and 1990’s that may be of additional value to the reader.

The purpose of this SAE Aerospace Information Report (AIR) is to present a quantitative approach for evaluating the performance and capabilities of an Engine Monitoring System (EMS). The value of such a methodology is in providing a systematic means to accomplish the following: 1 Determine the impact of an EMS on key engine supportability indices such as Fault Detection Rate, Fault Isolation Rate, Mean Time to Diagnose, In-flight Shutdowns (IFSD), Mission Aborts, and Unscheduled Engine Removals (UERs). 2 Facilitate trade studies during the design process in order to compare performance versus cost for various EMS design strategies, and 3 Define a “common language” for specifying EMS requirements and the design features of an EMS in order to reduce ambiguity and, therefore, enhance consistency between specification and implementation.

The purpose of this SAE Aerospace Information Report (AIR) is to provide management, designers, and operators with information to assist them to decide what type of power train monitoring they desire. This document is to provide assistance in optimizing system complexity, performance and cost effectiveness. This document covers all power train elements from the point at which aircraft propulsion energy in a turbine or reciprocating engine is converted via a gear train to mechanical energy for propulsion purposes. The document covers aircraft engine driven transmission and gearbox components, their interfaces, drivetrain shafting, drive shaft hanger bearings, and associated rotating accessories, propellers, and rotor systems as shown in Figure 1. For guidance on monitoring additional engine components not addressed, herein (e.g., main shaft bearings and compressor/turbine rotors), refer to ARP1839.

SAE Aerospace Information Report AIR1871 provides valuable insight into lessons learned in the development, implementation, and operation of various health monitoring systems for propulsion engines and drive train systems. This document provides an overview of the lessons learned for ground-based systems, oil debris monitoring systems, lubrication systems, and Health and Usage Monitoring Systems (HUMS) for military and commercial programs. For each case study, this document presents a brief technical description, the design requirements, accomplishments, lessons learned, and future recommendations. The lessons learned presented in this document represent a fragment of the knowledge gained through experience when developing and implementing a propulsion health management system. Previous versions of this document contain additional lessons learned during the 1980’s and 1990’s that may be of additional value to the reader.

For Engine Monitoring Systems to meet their potential for improved safety and reduced operation and support costs, significant attention must be focused on their reliability and validity throughout the life cycle. This AIR will provide program managers, designers, developers and customers a concise reference of the activities, approaches and considerations for the development and verification of a highly reliable engine monitoring system. When applying the guidelines of this AIR it should be noted that engine monitoring systems physically or functionally integrated with the engine control system and/or performing functions that affect engine safety or are used to effect continued operation or return to service decisions shall be subject to the Type Investigation of the product in which they'll be incorporated and have to show compliance with the applicable airworthiness requirements as defined by the responsible Aviation Authority.

ARP5120 provides recommended best practices, procedures, and technology to guide the physical and functional design, development, integration, verification, and validation of highly reliable Engine Health Management (EHM) systems for aircraft engines and Auxiliary Power Units (APUs). This SAE Aerospace Recommended Practice (ARP) also serves as a concise reference of considerations, approaches, activities, and requirements for producing the end-to-end engine health management system comprised of both on and off-board subsystems for the sensing, acquisition, analysis, detection, and data handling functions for EHM. These functions may also be used to effect continued operation or return to service decisions when demonstrated as compliant with the applicable airworthiness requirements defined by the responsible Aviation Authority. Where practical, this document delineates between military and commercial practices.

This SAE Aerospace Information Report (AIR) presents metrics for assessing the performance of prognostic algorithms applied for Engine Health Management (EHM) functions. The emphasis is entirely on prognostics and as such is intended to provide an extension and complement to such documents as AIR5871, which offers information and guidance on general prognostic approaches relevant to gas turbines, and AIR4985 which offers general metrics for evaluating diagnostic systems and their impact on engine health management activities.