PILOTS of CONTROL-IMPAIRED AIRCRAFT by ELAINE ANN
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ON-BOARD AUTOMATIC AID AND ADVISORY FOR PILOTS OF CONTROL-IMPAIRED AIRCRAFT by ELAINE ANN WAGNER B.S., Aerospace Engineering, Texas A&M University (1980) S.M., Aeronautics and Astronautics, Massachusetts Institute of Technology (1983) SUBMITTED TO THE DEPARTMENT OF AERONAUTICS AND ASTRONAUTICS IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY February 1988 © Massachusetts Institute of Technology, 1988 Signature of Author Department of Aeronautics and Astronautics Dcen>en 14, 1987 Certified by - a_ -- - Professor Lena Valavani Thesis Supervisor, Boeing Assistant Professor of Aeronautics and Astronautics Certified by Professor Wallace E. Vander Velde Professor of Aeronautics and Astronautics Certified L, - I[ m i- d Dr. Daniel R. Hegg ,/ Charlerv&3aff ¶aper Laboratory, Inc. Certified by Professor Harold Y. Wa:hman Chairman, Departmental Graduate Committee i,,l b :A C.'-.'U,'[:-/TStO.~ ~,Jrr i;. i F; r~ ,t..... u~-T(;¢/LOG', . ¢ , ;,;,;V~['( , '.1 .I F R GA I ',Di<" 1 -~ I- J3; Aero ON-BOARD AUTOMATIC AID AND ADVISORY FOR PILOTS OF CONTROLIMPAIRED AIRCRAFT by ELAINE ANN WAGNER Submitted to the Department of Aeronautics and Astronautics on December 14, 1987 In Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy ABSTRACT This thesis represents the consideration of the problem of aircraft control failures from a broader viewpoint than the usual control loop reconfiguration or redesign. The additional considerations involved in making full recoveries from control failures are categorized, and because it can be expected that pilots, if unaided, may continue often to be unable to recover aircraft, these considerations have been cast in the form of knowledge and capabilities that an automatic aid and pilot advisory system should have. Each major element of the categorization is supported with information from actual aircraft accident cases and from simulations of post-failure flight of a C-130 aircraft. Because automatic emergency control is seen to be a very significant part of the proposed system, a rule-based system to find a successful control strategy is developed for elevator failures on the C- 130 aircraft. The advisory function of the recovery-aiding system is described for various post-failure flight phases. The issues of pilot interface are discussed, and there is a treatment of the problem of deciding what to calculate to support the advisory. There is a discussion of post-failure explicit retrimming and some demonstrations of the real impact of this. The problem of evaluating and conveying precise post-failure control capabilities so that the information is accessible to pilots has been addressed. Thesis Supervisor: Lena Valavani Title: Boeing Assistant Professor of Aeronautics and Astronautics Thesis Supervisor Wallace E. Vander Velde Title: Professor of Aeronautics and Astronautics Thesis Supervisor Daniel R. Hegg Title: Technical Staff The Charles Stark Draper Laboratory, Inc. 2 Acknowledgements Because the worst battles fought in achieving this goal have been internal ones, my humblest and most sincere gratitude goes to those people who have supported me emotionally, and particularly those who, in this, were willing to offer guidance. Even though I failed to take much of the guidance to heart at first, I hope I have at last. To my incalculable good fortune, my mother has always strongly believed in my capabilities, and she has been a good teacher of many important things about humanity and love, not to mention persistence and perspective. The truly accepting and constant friendship of Julia Vail has greatly helped me to overcome in my final rounds of frustration here. There have been other friends, too: Mr. Ed Bergmann, who kept pushing me out the door; Capt. Neil McCasland, a very warm and generous man who also has a model ability to get things done; Janet Jones- and Joe Oliveira, for feeding me on holidays and for all the good thoughts; Dr. Craig Carignan, for years of support and companionship; and Scott Pace, an old and true friend. Dr. John McClure has always provided valuable honest advice and frank feedback, for which I am increasingly especially thankful. May I always be near people of such good heart. There have been so many other people who have been helpful. I would mention here Lt. Stephen Taylor, roommates Cathleen Corbett and Carolyn Lee, Dr. Paul Cefola, Dr. Janice Voss, Dr. Dan Hegg, Dr. Paul Motyka, Prof. Panos Antsaklis, Dr. Gunter Stein, and pilots Capt. Darrell Herriges and Lt. Col. Bob Herklotz. There have also been many other supportive and helpful people at Draper. Many thanks go to the several people who enabled me to use the many facilities there and who allowed me access to those people at Draper whose advice was so very important in completing this work; thanks especially to Dr. John Deyst and Dr. Eli Gai. Prof. Lena Valavani, who had the very difficult task of arranging for two years of support for this doctoral work, and Prof. Vander Velde have both been the best of sounding boards for my research. Mssrs. Mike McCarty and Ken Thompson at Lockheed-Georgia provided useful information on the C-130, as did Mr. Bruce Szepelak of the C-130E wing at Westover AFB, MA. My sister, Elizabeth Bucher, and her husband, Kevin, have helped me quite a bit by teaching me about their very different field. I am thankful, too, for the affection of my kid brother Bruce and his new wife, Karen, my cousin Sally Bolinger, who has always been good for a laugh, and for the support (financially, too) of my father. I am a very fortunate person in my family and friends. Help is gratefully acknowledged from the National Science Foundation, for a Graduate Fellowship; from the Charles Stark Draper Laboratory, for use of its computation, 3 simulation, and other facilities and for a last-semester IR&D fellowship; from the Office of Naval Research (Contract N00014-82-K-0582); and from NASA Ames and Langley Research Centers (NASA grant NAG-2-297). Permission is granted to the Charles Stark Draper Laboratory, Inc., to reproduce and to distribute copies of this thesis in whole or in part. Our whole life is startlingly moral. There is never an instant's truce between virtue and vice....The impure can neither stand nor sit with purity....From exertioncome wisdomand purity;from sloth ignoranceand sensuality. In the student, sensuality is a sluggish habit of mind ....If you would avoid uncleanness, and all the sins, work earnestly, though it be at cleaning a stable. Thoreau, Walden. "Higher Laws" "And will a man do better working at many trades, or keeping to one only?" "Keeping to one." Plato, The Republic 4 To Billye Ruth 5 Table of Contents Section Page Abstract 2 Acknowledgements 3 List of Symbols and Abbreviations 9 1. Introduction and Perspective on the Problem of Aircraft Control Failures 10 1.1. Introduction 10 1.2. Motivation for Treating the Problem 10 1.2.1. Accident Cases Involving Control Failures 10 1.2.2. Relevant Airworthiness Regulations and Flight Manual Information 16 1.2.3. Control Redundancy in Current and Planned Aircraft 20 1.3. Automatic and Piloted Recoveries in Perspective 24 1.3.1. When is an Automatic Response to a Control Failure Needed? 24 1.3.2. Concerning Detection and Isolation of Control Failures 25 1.3.3. Concerning the State of Research in Failure-Accommodating Control 26 1.3.4. Introduction to an Extended View of Recovery from Control Failures: The Flight 1080 Case 27 1.4. Thesis: More than Control Loop Reconfiguration is Required for Recovery 30 1.5. Focus and Overview of the Thesis 31 2. Concerning New Constraints and Explicit Retrim of the Control-Impaired Aircraft 33 2.1 Introduction 33 2.2. Post-Failure Operating Constraints 2.2.1. Controllability Airspeed-Type Limitations 33 2.2.2. Changes in Stall Airspeed 37 2.2.3. Changes in Control Reversal Airspeed 37 2.2.4. Other Types of Post-Failure Restrictions on Aircraft Operating State 38 2.3. Post-Failure Performance Constraints 38 2.3.1. Changes in the Power Required/ Power Available Situation and the Ramifications 38 2.3.2. Example from Work with C-130 Elevator Failures 40 2.3.3. Performance Changes in the Long Term 44 2.4. Post-Failure Equilibria and Other Retrim Information 44 2.4.1. Introduction: Context for Needs for Explicit In-Flight Retrim Post-Failure 44 2.4.2. Examples of the Need for Explicit Retrim (from C-130 Elevator Failure Cases) 47 6 2.4.3. Introduction to Constant-Rate State/ Control Input Regions for Aircraft Dynamics 50 2.5. Summary 50 3. A Rule-Based Expert System for Discovering Successful Emergency Post-Failure Control 51 3.1. Introduction 51 3.2. Introduction to Knowledge-Based Systems 53 3.3. System Developed for Thesis 54 3.3.1. Introduction 54 3.3.2. C-130 Elevator Failure Case Studies 54 3.3.3. Determining Effectiveness of Alternate Emergency Controls 57 3.3.4. Discussion of the Implementation 63 3.3.5. Overview of Rules in the Expert System 65 3.3.6. Examples of Usage of the Rule-Based System 67 3.3.6.1. -40 Off-Nominal Elevator Jam (Pitch Up) During Ascent, at 7000' 69 3.3.6.2. -9° Off-Nominal Elevator Jam (Pitch Up) During Ascent, at 7000' 72 3.3.6.3. Concerning Stall Recovery During Recovery from Pitch-Up Elevator Jam Failures 77 3.3.6.4. -8° Off-Nominal Elevator Jam (Pitch Up) During Ascent, at 7000' 78 3.3.6.5. -90 Off-Nominal Elevator Jam (Pitch Up) During Flight at 147 KIAS at 1000', with 50% Flaps Deployed 84 3.3.6.6.