DC-10, Windsor, Ontario, Canada
In June 1972, a potentially serious DC-10 trijet incident occurred after a cargo door failed on American Airlines .ight 96. The resulting decompression damaged controls to the tail. The center engine went to idle and had no control. The rudder was jammed with an offset, control of half of the elevator was lost, and the remaining half of the elevator had severe control cable binding. Electric but not mechanical stabilizer trim control was available, but the cockpit indicator showed no movement and the crew presumed it was inoperative and did not use it. With barely suf.cient pitch and full roll capability remaining, the airplane landed safely. During landing rollout, with the rudder offset and no nose wheel steering control available, differential reverse thrust was required to keep the airplane on the runway, but it ran slightly off the runway just before stopping (ref. 18).
DC-10, Paris, France
In March 1974, a DC-10 trijet, Turkish Airlines .ight 981, climbing out of Paris suffered a failure of the aft cargo door. The decompression buckled the cabin .oor, breaking or stretching control cables to the tail. The airplane impacted the ground at high speed in nearly level .ight, killing all 346 persons on board (ref. 19). Adding thrust to the wing engines possibly would have pulled the airplane out of the dive, although the trim condition might have been at a very high speed.
L-1011, San Diego, California
In April 1977, on a Lockheed L-1011 trijet, Delta Airlines .ight 1080, one of the horizontal stabilizers jammed in the full trailing edge-up position before an instrument .ight rules (IFR) departure out of San Diego. This failure resulted in a large nose-up pitching and rolling moment that almost exceeded the capability of the .ight controls. The airplane was just about to stall in the clouds, when the captain, using amazing insight, retarded the wing engine throttles and .rewalled the center engine. This action allowed him to regain enough control to maintain .ight. The crew learned rapidly, continued to use the throttles to supplement the remaining .ight controls, moved passengers forward to reduce the pitchup tendency, and completed a safe landing (ref. 20). A less capable crew would likely have not been able to save this airplane.
B-52, Dayton, Ohio
In May 1974, an eight-engine U.S. Air Force Boeing B-52H lost all tail hydraulic control because of a leak in a common drain line to the separate hydraulic reservoirs. The crew still had stabilizer trim for speed control and spoilers for roll control. For pitch, they used the throttles and airbrakes. All eight engines were functioning normally. The crew split the task, with one manipulating the throttles while another handled the airbrakes. The crew made a practice approach at 10,000 ft using these controllers and were satis.ed that they could land.
At that point, the gear was lowered; the upset caused them to lose 8000 ft before regaining control. In spite of these control dif.culties, the crew elected to try to land at Wright-Patterson AFB (near Dayton, Ohio). The phugoid was not adequately damped, and the aircraft hit the ground on the downswing of the phugoid. The impact broke off the nose section forward of the front landing gear. Fire consumed the rest of the airplane, but all eight crewmembers survived.
After this accident, several .ights were .own to determine the controllability of the B-52 with this type of failure, and procedures were developed. The procedures call for a .aps-up landing at a higher speed, which improves the pitch response to airbrakes.
B-52, Warner Robbins AFB, Georgia
In 1981, a similar failure occurred on an Air Force B-52G. The procedure that resulted from the Dayton accident was followed, and a landing was attempted at Warner Robbins AFB. The airplane hit hard enough to crack the fuselage, but there were no injuries and the airplane was repaired.
C-5A, Saigon, Vietnam
In 1973, an Air Force Lockheed C-5A four-engine military transport was carrying 300 orphans on an evacuation .ight in Vietnam (ref. 21). Climbing through 23,000 ft, the rear pressure bulkhead, which is part of the cargo-loading ramp, failed, causing secondary damage to the aft fuselage and loss of all hydraulic controls for the tail. The aircraft remained roughly in trim, and all wing-mounted control surfaces and .aps were still available. Pitch was controlled with throttles. The crew practiced using this control mode for 30 min, and commented on the dif.culty in achieving precise control because of the slow response of the engines.
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