F/A-18, Indiana
In 1989, over Indiana, a U.S. Navy McDonnell Douglas F/A-18 twin-engine .ghter had a failure of the dam seal in the right horizontal tail actuator, which caused loss of all hydraulic .uid from both systems. All .ight control surfaces were then inoperative. The airplane initially remained in trim then experienced a slow rolloff to the right. When the roll reached 90° , the pilot ejected.
F/A-18, Sea of Japan
A Navy F/A-18 .ghter experienced a failure of the left horizontal tail linear variable differential transformer position feedback indicator. This failure resulted in extreme actuator inputs of random size and timing. With the airplane uncontrollable in this mode, the pilot selected the backup mechanical control system, which operated normally but is not recommended for landing. After repeated tries to reselect the digital mode, each causing wild gyrations, the pilot reselected the mechanical system, went out over the ocean, and ejected.
XB-70A, Edwards AFB, California
In 1966, the six-engine Air Force XB-70A airplane was involved in a mid-air collision, which tore off both vertical tails. The airplane slowly diverged in yaw and entered a spin. One crewmember ejected but was injured, while the other was unable to eject and was killed. A PCA system should have been able to maintain control at least until all crewmembers could safely eject.
F-14A, Long Island, New York
The number 1 Navy Grumman F-14A twin-engine .ghter airplane experienced cracks in titanium hydraulic lines on its .rst .ight. On approach, the last hydraulic .uid was lost, and control was lost. The crew ejected safely.
Vietnam War Statistics
Historical data from Southeast Asia operations in the 1970–1980 time period show that, of the more than 10,000 aircraft lost, 18 percent were lost because of .ight control failure. How many of these aircraft could have been saved with a PCA system is unknown.
DESCRIPTION OF THE MD-11 AIRPLANE
The MD-11 is a large, long-range, three-engine wide-body transport. The airplane, shown in .gure 1, is 202 ft long and has a span of 170.5 ft. The test airplane, ship 560, was con.gured for .ight test and had no interior furnishings other than data analysis and recording consoles.
Flight Control Systems
The MD-11 has a mechanical .ight control system, with irreversible hydraulically actuated surfaces. Three independent systems provide hydraulic power. All essential control functions can be maintained on any one of these three systems. Dual elevators provide pitch control, and a hydraulic jackscrew-actuated horizontal stabilizer provides pitch trim. Inboard and outboard ailerons supplemented by wing spoilers provide roll control. Dual rudders
(a) Three-view.
Figure 1. McDonnell Douglas MD-11 test airplane.
EC95 43247-04
(b) At touchdown. Figure 1. Concluded
on a single vertical tail provide yaw control. In case of hydraulic failure, the stabilizer would effectively lock, and other surfaces would .oat.
The MD-11 is equipped with a hydraulically actuated wing leading and trailing edge high-lift system. Full-span slats are installed on the leading edge; these can be extended by moving the .ap handle in the cockpit to the .rst detent. Moving the .ap handle farther begins to extend the trailing edge .aps. For takeoff, .aps are in the range from 10° to 28° . For landing, maximum .ap extension is 40° . In case of hydraulic failure, the leading edge slats would remain extended, the trailing edge .aps would slowly drift up.
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本文链接地址：Development and Flight Test of an Emergency Flight Control System Using Only Engine Thrust on an MD-11 Transport Airplane(10)
