United Airlines Flight 232 - Similar Accidents

Similar Accidents

The odds against all three hydraulic systems failing simultaneously had previously been calculated as high as a billion to one. Yet such calculations assume that multiple failures must have independent causes, and similar flight control failures have actually occurred:

• In 1971 a Pan American 747 struck approach light structures for the reciprocal runway as it lifted off the runway at San Francisco Airport. Major damage to the belly and landing gear resulted, which caused the loss of hydraulic fluid from three of its four flight control systems. The fluid which remained in the fourth system gave the captain very limited control of some of the spoilers, ailerons, and one inboard elevator. That was sufficient to circle the plane while fuel was dumped and then to make a hard landing. There were no fatalities, but there were some injuries.
• In 1981, a Lockheed L-1011, operating as Eastern Airlines Flight 935, suffered a similar kind of massive failure of its tail-mounted number two engine. The shrapnel from that engine inflicted damage on all four of its hydraulic systems, which were also close together in the tail structure. Fluid was lost in three of the four systems. While the fourth hydraulic system was impacted with shrapnel, too, it was not punctured. The hydraulic pressure remaining in that fourth system enabled the captain to land the plane safely with some limited use of the outboard spoilers, the inboard ailerons, and the horizontal stabilizer, plus differential engine power of the remaining two engines. There were no injuries.
• In 1985, Japan Airlines Flight 123, a Boeing 747, suffered a rupture of the pressure bulkhead in its tail section. The damage was extensive and caused the loss of fluid in all four of its hydraulic control systems. The pilots were able to keep the plane airborne for almost 30 minutes using differential engine power, but eventually control was lost, and the plane crashed in mountainous terrain. There were only 4 survivors among the 524 on board. This accident is the deadliest single-aircraft accident in history.
• In 1994, RA85656, a Tupolev Tu-154 operating as Baikal Airlines Flight 130, crashed near Irkutsk shortly after departing from Irkutsk Airport, Russia. Damage to the starter caused a fire in engine number two (located in the rear of fuselage). High temperatures during the fire destroyed the tanks and pipes of all three hydraulic systems. The crew lost control of the aircraft. The unmanageable plane, at a speed of 275 knots, hit the ground at a dairy farm and burned. All passengers and crew, as well as a dairyman on the ground, died.
• In 2003, OO-DLL, a DHL Airbus A300 was struck by a surface-to-air missile shortly after departing from Baghdad International Airport, Iraq. The missile struck the port side wing, rupturing a fuel tank and causing the loss of all three hydraulic systems. With the flight controls disabled, the crew was able to use differential thrust to execute a safe landing at Baghdad. This is the first and only documented time anyone has managed to land a transport aircraft safely without working flight controls.

The disintegration of a turbine disc, leading to loss of control, was a direct cause of two major aircraft disasters in Poland:

• On March 14, 1980, LOT Polish Airlines Flight 007, an Ilyushin Il-62, attempted a go-around when the crew experienced troubles with a gear indicator. When thrust was applied, low pressure turbine disc in engine number 2 disintegrated because of material fatigue; parts of the disc damaged engines number 1 and 3 and severed control pushers for both horizontal and vertical stabilizers. After 26 seconds of uncontrolled descent, the aircraft crashed, killing all 87 people on board.
• On May 9, 1987, improperly assembled bearings in Il-62M engine number 2 on LOT Polish Airlines Flight 5055 overheated and exploded during cruise over Lipniki village, causing the shaft to break in two; this caused the low pressure turbine disc to spin to enormous speeds and disintegrate, damaging engine number 1 and cutting the control pushers. The crew managed to return to Warsaw, using nothing but trim tabs to control the crippled aircraft, but on the final approach, the trim controlling links burned and the crew completely lost control over the aircraft. Soon after, it crashed on the outskirts of Warsaw; all 183 on board perished. Had the plane stayed airborne for 40 seconds more, it would have been able to reach the runway.