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The worst plane crash in US history: how human error killed nearly 300 people

Even after 42 years, this disaster remains one of the largest in US history: a DC-10 liner with 271 people on board crashed into a trailer park near Chicago, Illinois, half a minute after takeoff. The DC-10 had been in the news before, but this time the reason was not a miscalculation of the engineers: almost 300 people died due to the desire of the mechanics to simplify their work a little - to deviate from the rules and make repairs not as needed, but as convenient. The edition told in more detail Tech Onliner.

Photo: Shutterstock

Problematic DC-10

The early 1970s were a landmark time for passenger air travel: the steady demand and growing popularity of flights led to the emergence of wide-body airliners that offered a different level of comfort compared to the cars of yesteryear.

The niche of long-haul aircraft, capable of taking on board more than 300 passengers, was formed and occupied by the American Boeing 747 and McDonnell Douglass DC-10, and a little later the European Airbus A300 joined them.

The DC-10 was slightly smaller than the Boeing 747 and received three engines instead of four. Fuel consumption in those years was not a significant problem, but still three engines will be more economical in every way than four, and this can be counted among the advantages of the DC-10.

In the 1970s, there was a safety requirement for flights across the ocean: only liners with at least three engines could make such flights. And no one would produce a wide-body aircraft that cannot cross the Atlantic. Only ten years later, in 1981, the Boeing 767 will become the first twin-engine aircraft to be allowed to fly to a destination across the ocean.

The DC-10 itself cannot be called successful: just three years after the start of operation, a major disaster happened - a Turkish Airlines liner crashed in France, 346 people died.

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It turned out that the design of the tailgate had a serious flaw, because of which it could not be closed completely. In flight, the door could not withstand the pressure and swung open, causing severe damage. Besides the catastrophe in France, there were other incidents involving the door. But this drawback was eliminated, and the rest of the DC-10 did not cause problems.

31 second

But on May 25, 1979, the whole world started talking about the DC-10 again. An American Airlines flight was flying from Chicago to Los Angeles. The crew in the cockpit consisted of three people. The flight engineer and both pilots are veterans of American Airlines: Commander Walter Lacks worked as a pilot for 28 years and flew 22,5 thousand hours, co-pilot James Dillard had more than 9 thousand flight hours, and flight engineer Alfred Udovich - more than 15 thousand. the crew consisted of ten flight attendants. There were 258 passengers on board.

The plane began to accelerate along the runway and reached a speed of about 320 km / h. Almost simultaneously with the separation of the front chassis from the strip, a dull impact was heard in the cockpit. The liner had to take off in any case, it would not have had time to stop before the end of the runway.

In the cockpit, they realized that something serious had happened, since the thrust in the left engine had completely disappeared. However, the pilots did not know how critical their situation really was: the blow they heard came as a result of the separation of the left engine along with the mount from the wing. The engine was thrown up, it hit the wing, destroyed the electrics with the hydraulics of the wing mechanization and remained on the runway.

The aircraft was raised to a height of about 91 meters, after which the nose began to drop. By itself, the separation of the engine did not mean an obligatory disaster, but the wing mechanization systems were damaged. As a result, the slats needed to increase lift at low speed began to retract. At the same time, there was no damage on the right side, and the mechanization was released. This situation led to an imbalance and stall, from which the aircraft cannot be withdrawn at such a low altitude.

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The crew even ignored the dispatcher's question, who saw the engine detached from the aircraft from the tower: "American 191, do you want to return and to which lane?" There was no time for an answer: the liner spent only 31 seconds in the air, after which it fell into the parking lot of mobile homes.

Fall place

The full fuel tanks exploded instantly. The firefighters were on the spot within four minutes after the crash, but, according to their recollections, it immediately became clear: there was no one to save here. Not only did the plane crash to smithereens, but also tens of tons of ignited fuel finally deprived at least someone of the chance of survival. In addition to the 271 people on the DC-10, two from the trailer park were killed and two others on the ground were severely burned.

The work at the site of the disaster was especially difficult: the victims were burned so that even seasoned firefighters could not always understand where the remains of a person were and where not. The policeman, one of the first to arrive at the crash site, recalled that after what he saw, he could not grill for a long time. The fire also greatly hampered the further identification of the victims: many had to be identified by their teeth. Thirty victims were never identified.

At the crash site, there was almost no information valuable to the investigators: a lot of evidence was destroyed by a fire. Therefore, they took up the first engine remaining on the airport lane. This in itself was strange: the physical loss of the power plant is an almost unique situation.

Maintenance features

The US Federal Aviation Administration (FAA) required DC-10 operators to check aircraft engine attachments to the wing. This mount is called a pylon, it looks like a large metal fragment that comes out of the wing. Several airlines, following the FAA instructions, noted that they found problems in the attachment points: the metal was worn out, the heads of some bolts were torn off. After such information, DC-10 was banned from flying - the certificate of validity was revoked on June 6, 12 days after the disaster in Chicago.

Investigators examined McDonnell Douglas' documentation on engine maintenance and pylon replacement. The instructions explicitly say that you need to remove them separately. For example, if you need to get to the pylon, then you cannot unscrew it together with the engine - you must first remove the power plant, and then the pylon. This, of course, is more difficult and longer than removing the assembled parts: it will take about 200 extra man-hours in the case of one aircraft. Then the simple economics begins: the longer the plane is on the ground, the longer it does not bring money to the airline, and the longer the service lasts, the more you need to pay ground personnel. To simplify the life of the mechanics when servicing the aircraft, they decided to use their own technology.

Two months before the crash, the DC-10 was undergoing maintenance, which involved removing the engines. For this, the mechanics used a forklift with a form on the forks, into which the engine nacelle was lowered. The problem is that it was necessary to hit the mount with filigree precision: if you miss, and one part of the engine will sag, creating a strong load on the pylon-to-wing mounts. This is exactly what happened with the plane of Flight 191. On the pylon of the detached engine, experts even discovered damage that happened precisely during the improper removal of the engine.

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None of the mechanics noticed the problem, after passing the maintenance the DC-10 was returned to the flights. The resulting crack withstood the load for two months - and all this time it was a time bomb. Finally, on May 25, the metal broke, leading to the largest plane crash in US history.

The DC-10, like other airliners, is capable of continuing its flight without one engine. But another surprising thing came to light: there was a serious flaw in the instructions that the crew followed. The documentation demanded that the speed be reduced if the slats were not working correctly. The pilots did so, but in reality it only made the situation worse. However, the crew has nothing to show: they rightly relied on the instructions, which were drawn up by the manufacturer himself.

Two years later, in March 1981, 47-year-old Earl Russell Marshall, an employee of the American Airlines repair department, committed suicide. He was not directly responsible for the maintenance of the crashed DC-10, however, according to the widow, he blamed himself for the crash of the liner.

The FAA fined American Airlines $ 500 thousand for improper aircraft maintenance, and Continental Airlines received a $ 100 thousand fine: local mechanics acted in a similar way when removing the engine. They also had to make changes to repair methods and improve compliance with aircraft manufacturers' orders.

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