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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.

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 Aerospace Recommended Practice (ARP) is a general overview of typical airborne engine vibration monitoring (EVM) systems applicable to fixed or rotary wing aircraft applications, with an emphasis on system design considerations. It describes EVM systems currently in use and future trends in EVM development. The broader scope of Health and Usage Monitoring Systems, (HUMS) is covered in SAE documents AS5391, AS5392, AS5393, AS5394, AS5395, AIR4174. This ARP also contains the essential elements of AS8054 which remain relevant and which have not been incorporated into Original Equipment Manufacturers (OEM) specifications.

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.

This Aerospace Information Report (AIR) is a general overview of typical airborne engine vibration monitoring (EVM) systems applicable to fixed or rotary wing aircraft applications, with an emphasis on system design considerations. It describes EVM systems currently in use and future trends in EVM development. The broader scope of Health and Usage Monitoring Systems, (HUMS ) is covered in SAE documents AS5391, AS5392, AS5393, AS5394, AS5395, AIR4174.

The purpose of this SAE Aerospace Information Report (AIR) is to provide information and guidance for the selection and use of lubrication system monitoring methods. This AIR is intended to be used as a technical guide. It is not intended to be used as a legal document or standard. The scope of this document is limited to those inspection and analysis methods and devices that can be considered appropriate for routine maintenance.

This document applies to prognostics of gas turbine engines and its related auxiliary and subsystems. Its purpose is to define the meaning of prognostics with regard to gas turbine engines and related subsystems, explain its potential and limitations, and to provide guidelines for potential approaches for use in existing condition monitoring environments. It also includes some examples.

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.

An effective GSS is vital to the successful implementation of an EMS and is a fundamental part of the total monitoring system design, including asset management. Unlike the on-board part of the EMS which principally uses real time data to indicate when engine maintenance is required, a GSS can offer much greater processing power to comprehensively analyze and manipulate EMS data for both maintenance and logistics purposes. This document reviews the main EMS functions and discusses the operating requirements used to determine the basis design of a GSS, including the interfaces with other maintenance or logistic systems. A brief discussion is also included on some of the more recent advances in GSS technology that have been specifically developed to provide more effective diagnostic capabilities for gas turbine engines.

The SAE Guide to APU health management establishes the foundation for developing a successful APU health management program at any aircraft or APU operator, such as an airline, an OEM, an equipment supplier, or a military transport unit. This guide identifies the best practices for using an APU health management program to improve dispatch reliability and to satisfy Extended Operations (ETOPS) availability requirements.

This AIR is a general overview of typical airborne vibration monitoring (AVM) systems with an emphasis on system hardware design considerations. It describes AVM Systems currently in use.

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 the gas generator energy is transferred to mechanical energy for propulsion purposes. The document covers engine power train components, their interfaces, transmissions, gearboxes, hanger bearings, shafting and associated rotating accessories, propellers and rotor systems as shown in Figure 1. This document addresses application for rotorcraft, turboprop, and propfan drive trains for both commercial and military aircraft.

The purpose of this SAE Aerospace Information Report (AIR) is to provide information that would be useful to potential users/operators and decision makers for evaluating and quantifying the benefits of an Engine Monitoring Systems (EMS) versus its cost of implementation. This document presents excerpts from reports developed to analyze “actual aircraft cost/benefits results”. These are presented as follows: a First, to outline the benefits and cost elements pertaining to EMS that may be used in performing a cost versus benefits analysis. b Second, to present considerations for use in conducting the analysis. c Third, to provide examples of analyses and results as they relate to the user/operator and decision-maker community. The document encompasses helicopters and fixed wing aircraft and distinguishes between civilian and military considerations.

This SAE Aerospace Standard (AS) provides guidelines for the functional, performance, qualification and acceptance testing, and documentation requirements for the components of an airborne engine vibration monitoring (EVM) system which is intended for use as a turbojet engine rotor unbalance indicating system, per FAR 25.1305 (D)(3) on transport category airplanes. For the purpose of this document, this means a system which can provide real-time flight deck displays of engine vibration caused by rotor unbalance, throughout the flight envelope, which are suitable for: a Relating to engine vibration limits (where such limits are specified) b Use in ice shedding procedures c Helping the flight crew to determine which engine has the higher level of vibration, following an engine damage event. As a minimum, the functional capability for such a system shall include the ability to compute and display vibration levels specifically related to the rotational speed(s) of the engine rotor(s).

To establish a specification for software input and output interfaces for condition monitoring and performance programs used to monitor equipment from multiple manufacturers. The purpose of standardizing these interfaces is to improve operational flexibility and efficiency of monitoring systems as an aid to cost effectiveness (e.g., easier implementation).

This SAE Aerospace Information Report (AIR) is a general overview of typical airborne engine vibration monitoring (EVM) systems with an emphasis on system design considerations. It describes EVM systems currently in use and future trends in EVM development.