Propulsion Controlled Aircraft

In July 1989, the tail engine of the DC-10 of United Airlines Flight 232, enroute from Denver to Minneapolis, sustained a "catastrophic uncontained failure" that created a hail of shrapnel, slicing the hydraulics lines of all three independent systems, leaving the aircraft "marginally controllable" at 37,000 feet. Contrary to the realistically motivated consensus at that time that this flight should have ended in disaster, Captain Al Haynes, with the help of United Captain and DC-10 Flight Instructor Dennis Fitch, quickly improvised a way to keep control of the aircraft by maneuvering the throttles of the remaining wing engines. To the great amazement of aviation officials, the crew managed to bring the aircraft to a crash landing in Sioux City, Iowa, saving the lifes of most of those on board.

In the aftermath of the Sioux City accident, and following a recommendation of the National Transportation Safety Board, the Propulsion Controlled Aircraft (PCA) problem emerged as the problem of designing "pilot friendly" back-up control systems that use the engines as only actuators in case of failure of the primary hydraulic control system. NASA Dryden Flight Research Center managed this line of investigation and subcontracted part of the work to various institutions, the University of Southern California among others. In August 1995, the NASA propulsion controlled MD-11, under the command Test Pilot (and former Space Shuttle Astronaut) Gordon Fullerton, made a smooth landing using wing engine thrust only.

Our contribution to this problem is propulsion control by H-infinity model matching. This approach consists in linearizing the flight dynamics around a certain point of the envelope and designing a linear feedback from the state of the crippled aircraft to its engines so that the response of the throttle actuated crippled aircraft to command inputs matches, optimally in the H-infinity sense, the response of the nominal control surface actuated model. To cover the whole flight envelope, such gain scheduling techniques as radial based neural network, artificial neuro-fuzzy inference, simplicial approximation, etc. have been developed. The trade-off between global linearization and gain scheduling are also being investigated.

PCA for such aircraft as the Lockheed L-1011 "Tristar", the Fokker F-27, and a statically unstable thrust vectoring aircraft have been designed. Most of the research has been devoted to the L-1011, because of its "trijet" configuration close to that of the DC-10 of Sioux City. In fact, in a similar incident, an L-1011 sustained a "catastrophic uncontained failure" of its tail engine, resulting in serious damage to the hydraulic system; however, this last incident had a happier ending than in Sioux City, because of the superior redundancy of the L-1011 hydraulic system.

The specific part of this research aimed at airplane was phased out around 1999. For about one year thereafter, the techniques developed in this research were applied to propulsion control of such reusable launch vehicles as the X-33 and the VentureStar:

This research was supported by the National Aeronautics and Space Administration under Contract NASA-Ames-94-030.

Photo:

Selected Publications:

Book Chapter

  1. E. A. Jonckheere, P. Lohsoonthorn, and S. K. Bohacek, "From Sioux-City to the X-33," in Annuals Reviews in Control (Elsevier/Pergamon), vol. 23, pp. 91-108, 1999.

Journal Papers:

  1. E. A. Jonckheere and G.-R. Yu, ``Propulsion control of crippled aircraft by H-infinity model matching,'' IEEE Transactions on Control Systems Technology, vol. 7, pp. 142-159, March 1999.

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  2. E. A. Jonckheere and G.-R. Yu, ``H-infinity longitudinal control of crippled trijet aircraft with throttles only,'' invited paper,  IFAC Control Engineering Practice, International Federation of Automatic Control (IFAC), vol. 6, No. 5, pp. 601-613, 1998.

Conference Papers:

  1. E. A. Jonckheere, Gwo-Ruey Yu and Chung-Kuang Chu, ``H-infinity control of crippled aircrafts with throttles only,''' IFAC 1996 Triennial World Congress, Session 8a-08, Flight Control Systems, San Francisco, California, June 30-July 5, 1996, pp. 219-224.
  2. E. A. Jonckheere, G.-R. Yu, and C.-Y. Chiang, ``H-infinity control of crippled aircraft in lateral motion with throttle only,'' IEEE Conference on Decision and Control, Kobe, Japan, Dec. 11-13, 1996, WP-16, pp. 1583-1585.
  3. C.-K. Chu, G.-R. Yu, E. A. Jonckheere and H. Youssef, ``Gain scheduling for fly-by-throttle flight control using neural networks,'' IEEE Conference on Decision and Control, Kobe, Japan, Dec. 11-13, 1996, WP-19, pp. 1557-1562.
  4. E. A. Jonckheere and Gwo-Ruey Yu, ``Gain scheduling for lateral motion of propulsion controlled aircraft using neural networks,'' American Control Conference, Albuquerque, NM, June 04-06, 1997, pp 366-371.

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Major Airplane Manufacturers:


Other Sites of Interest:

Latest News: The aircraft hit by a missile in Baghdad had lost all of its hydraulic power and the crew made an emergency landing using engines only:

Following the Aviation Week & Space Technology Magazine, the DHL Airbus 300 aircraft hit by a missible on November 22, 2003 while taking off from Baghdad had lost all of its hydraulic power and the crew managed to make an emergency landing using engines only. INCREDIBLY, the DHL captain had attended an aviation safety seminar given in Brussels by Al Haynes, who under similar dramatic circumstances had to crash land his hydraulically crippled DC-10 in Sioux City using engines only.

Following USAviation the Airbus was hit by a SAM heat seeking missile and it therefore comes as no surprise that the aircraft lost all of its hydraulics. Indeed, a heat seeking missile will most likely hit the exhaust pipes of the engines and as such will most likely damage the trailing edge of the wing. Since the hydraulic lines of all (3 or 4 depending on the aircraft) redundant systems are running along the trailing edge to power the actuators to the ailerons and flaps, it is not surprising that the hydraulic system is particularly vulnerable to these kinds of attacks.


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