This SAE Aerospace Information Report (AIR) contains technical information on aerospace hydraulic, actuation and support equipment technologies lessons learned. The lessons learned were prepared by system designers and hydraulic engineers from the aerospace industry and government services as part of SAE Committee A-6, Aerospace Fluid Power, Actuation, and Control Technologies, and were presented at eight Lessons Learned Symposia from 1989 through 1999 held during A-6 Committee meetings. The technical topics represent many years of design experience in hydraulics and actuation, which it is felt is a resource for learning that should be documented and made available to current and future aerospace hydraulic engineers and designers. The document is organized into two sections: systems and components with further categories within the components section. The information topics are presented in a concise format of problem, issue, and solution, with accompanying descriptive diagrams and

A-6 Aerospace Actuation, Control and Fluid Power Systems

Intelligent Damage Adaptive Control for Commercial Air Transports

1999-01-143604/13/1999

In situations of unanticipated maneuvers of an aircraft, information must be immediately received by the aircrew for correcting the aircraft flight path to a safe trajectory for continued flight and landing. These maneuvers may be due to failures in the control system, wind gust upsets, or other off-nominal conditions. Also critical are situations of control maneuvers that exceed the normal flight envelope of the aircraft, and providing information to the pilot and control system that will result in safe return to controllable flight. The Intelligent Damage Adaptive Control System (IDACS) operates during flight to detect dangerous conditions of the aircraft and to provide the crew with assistance to restore and to maintain safe control. This system is being developed by Boeing for NASA.

Urnes, James M.

Development of a Maintenance Free Self-Lubricating Ball Joint

1999-01-003603/01/1999

Vehicular suspension ball joints can be categorized in the family of tribological systems which can reduce useful service or working capacity through malfunction or breakdown. Detailed metallurgical analysis of the friction and wear mechanisms on typical ball joint bearing surfaces point to a Teflon-based woven fabric, self-lubricating liner as the best bearing material for the joint. Laboratory functional testing was conducted on modern, 4-axis test equipment simulating the applicable loading and motion conditions typically encountered in use. The self-lubricated bearing liner woven with Teflon thread demonstrated higher sustained load capacity, less rotating friction, excellent torque retention qualities and extended life in comparison to existing components utilizing greased metal-on-metal and/or “plastic” bearing materials. This paper describes how the advanced Fiberglide® liner technology and redesigned suspension ball joint provides superior performance and maintenance-free

Arnold, R., Shuster, M., Maughan, G.

Analysis of Tiltwing Aircraft Configuration Potential

96229011/18/1996

This paper outlines work performed by the Aeronautical Systems Division of the Aerospace and Transportation Laboratory at the Georgia Tech Research Institute (GTRI). The paper provides limited, but pertinent information relative to the technical viability of a tiltwing configurations as civil powered-lift aircraft. Emphasis has been placed on identifying the complexity differences with tiltrotor and helicopter configurations. Complexity differences normally impact both acquisition and/or operating and support costs, although specific cost estimates are not presented.

Crawford, Charles C., Heiges, Michael W., Wasikowski, Mark

Issues Associated with Operator Use of Automation

95198509/01/1995

Automation is currently a topic of great interest. Part of the reason for this may be that problems associated with operator use of automation can be relatively subtle yet severe. When designing an automated system, it may not be obvious how the interactions between the operator, the system, and the environment may lead to errors. Consequently, those who design and certify flight deck systems should be aware of some of the issues associated with pilot use of automation. These include the potential for over reliance or under reliance on automation and the factors that can contribute to them, issues of pilot and automation authority, automation complexity, feedback, and transitions between automated and manual control. In this paper, we concentrate on how pilots make decisions to use or not use automation and the factors that can influence these decisions.

Riley, Victor

A Millimeter Wave, Wireless, LAN for Use Inside an Aircraft

94255411/01/1994

A Millimeter Wave, Wireless, Local Area Network has been built for use in distributing digital data inside an aircraft. To avoid interference with existing VHF and Microwave transmitters and receivers, the transmitters operate at 60.60 Ghz and 60.54 Ghz. This region of the Millimeter Wave Spectrum has high attenuation being the resonant frequency of local oxygen atoms. This isolates the wireless links from most interference. The transceivers employ V-Band Gunn Diode Voltage-Controlled Oscillators. The maximum range is 150 meters. The network boards have been optimized for Mil-Spec-1553 type digital messages. A wide variety of other digital formats can be supported from 200 Khz up to video rates, but analog video sent through the system was too noisy for conventional television receivers. This paper describes the rationale, the system requirements, the development, the final design, and the test results.

Ulbrich, Erwin A.

Trends in Air Turbine Starters for Large Turbofan Engines

92197510/01/1992

Methodology development from analysis using both starter parameter trends and auxiliary system features can be applied to focus future starter development efforts. This analysis method can be used to devise improvements to the starter system and its supporting systems and equipment. Results of historic development trends of air turbine starter characteristics, parameters and features are examined for basic trends and for state-of-the art limits. This analysis of parameter relationships and of current examples breaks-down paradigms to realize previously unseen component and system advances. The data from analysis provides a new platform for starter development that can bring maximum overall value to the customer.

Kasak, A. John

Continuing the Etops Debate A Philosophy of Safety Overview

90202109/01/1990

Five years ago, a new experiment in passenger air transportation for Atlantic Ocean crossings was introduced. It was given the acronym known as ETOPS and involves the development of passenger aircraft having only two-engines utilized for flights over such critical routes. The essence of the concern generated in this study is summarized by the safety analysis of Dr. Robert Besco, who states, “ETOPS is troublesome because the failure of only one system on an aircraft [In this case an engine] should not cause that aircraft to have to operate under emergency conditions.” Previously, a major cornerstone of civil aviation safety was the concept of providing multiple engine redundancy with a minimum of three-engines required for such critical flights. The accepted safety premise was that many unfavorable factors such as engine failures could jeopardize such flights and therefore the fail-safe method of providing three- or four-engine redundancy for these transports was prudent as well as

Sprogis, Hal

Airbus A320 Side Stick and Fly By Wire — An Update

86180110/01/1986

This paper discusses the side stick and fly by wire elements of the Airbus Industrie A320. After discussion of the cockpit and the effect on it of the side sticks, the arrangements of the side sticks themselves is discussed, travel, forces and electronic coupling. The control laws form the body of the paper with some emphasis on the new things that become possible with fly by wire that Airbus Industrie has vested in A320. Pitch roll and yaw control are discussed in detail and so to are the protection systems that will contain the flight path within safe limits. Some illustrations of the functioning of the protection system in flight on a test A300 equiped with the A320 control laws will be presented.

Corps, S. G.

Automotive Electronics in Japan - The Next Five Years

851654

10/01/1985

This paper deals with the current status and the future prospects in automotive electronics in Japan. Electronics systems have been individually developed for the engine, transmission, brakes, suspension, instrument panel and other areas. The next challenge will be to link these standalone systems together with interactive control blocks: for example, powertrain, vehicle control and body control. These blocks, in turn, will be coupled together by data communications links, and they will be linked through communications to data sources existing outside the automobile. Control technology will change from PID control to modern control theory and this will impact on microprocessor architecture. These control systems will increase the controllability, reliability and serviceability of the automobile as a whole.

Mizutani, Shuji, Ohtake, Toshikazu

Advanced Digital Optical Control Actuation for the ADOCS

85175510/01/1985

The digital fly-by-wire control systems currently being developed for next generation aircraft are not immune to lightning, electromagnetic interference (EMI), and electromagnetic pulse (EMP). Optical commands signals transmitted via fiber optic links, and optical digital transducers to generate feedback signals, provide the means to overcome this hostile environment. This paper describes the major elements of a Driver Actuation System compatible with an Advanced Digital Optical Control System (ADOCS), and demonstrates the feasibility of the design concept through presentation of bench and aircraft integration test results.

Sherif, Fouad E.

A New Electronically Controlled Injection Pump for Diesels

850169

02/01/1985

An electronically controlled rotary-type diesel fuel injection pump has been developed to provide full authority fuel and timing control for light-duty diesel engines in automotive, agricultural and industrial engine applications. Vehicle testing to date on a 4.3 liter V-6 and a 6.2 liter V-8 diesel engine has resulted in obtaining superior performance in several areas when compared with engines equipped with their original mechanical fuel injection pumps. An eight-bit single chip microcomputer, and linear stepper motors, along with engine and vehicle mounted sensors provide the full authority electronic control functions.

Maynard, A.