aircraft maintenance
What causes abnormal aircraft maintenance

Aircraft maintenance and fatal error.    


           In January 2000, a jet airliner owned by the companyAlaska Airlines"88 with passengers and crew on board crashed and fell into the water. Negligence and irresponsibility led to a terrible catastrophe. When one of the engineers said the repairs are not enough quality, he was suspended from work. The investigation revealed the glaring facts of neglect of duty. It showed that a number of unforgivable mistakes led to the tragedy, which may again be repeated. Next you will see the consequences of improper aircraft maintenance.


            Puerto Vallarta is a famous Mexican resort on the Pacific coast. Most of the passengers on the 261 flight were returning from vacation. They are in the mood for a long flight to San Francisco. At the controls of the aircraft were experienced pilots. The captain is Ted Thompson and the co-pilot is William Tansky. They have flown thousands of hours on MD-83 and we knew very well this car. MD-83 was very reliable, well-controlled aircraft.


            31 January 2000, when the 261 board was preparing for takeoff, the pilots did not assume that there was a deadly danger in the tail of the aircraft. Shortly after takeoff, the captain and the co-pilot felt that something was not right with the car. Jammed horizontal stabilizer, located in the tail of the plane. The pilots were trying to figure out what to do next.


            The stabilizer on the MD-83 aircraft was a horizontal plane 12 meters wide. There, in the tail section, were located two elevators. With the help of a stabilizer and elevators, the angle of flight was adjusted. The stabilizer jammed, and the pilots thought it was due to electric motors that moved the stabilizer up and down. They did not suspect that the situation was much more serious. The pilots thought that they themselves would cope with this problem.


Expert: They are not alerted by the fact that the stabilizer jammed. They thought it was a small problem and concern for no particular reason.


            The crew believed that the stabilizer was not acting because the jack was not working. To put it into action, the pilots tried to use two switches at once, one of which was at the helm and the other on the control panel. Without a stabilizer it was impossible to level the plane. He was always drawn to the ground. At the height of 8500 meters pilots disengage the autopilot and fly a plane manually. They had to pull forces from all over the helm to align the plane. It took a huge physical effort. 7 minutes later they scored the flight height - 10000 meters. Flying over the coast, they are connected with the repair service of its airlines. Unfortunately, the repair service does not able to help them.


Expert: Pilots acted blindly. They pulled all the switches, which are responsible for the stabilizer, and hoped that it will work.


            Pilots wondered if they could land safely. It was not known how the plane would behave in the next second. All the time the flight crew operated the aircraft manually. The airliner constantly buried its nose, and they descended to the height of 6100 meters. The crew made another attempt to activate the stabilizer. For this, they powered two electric motors at once. However, the next moment they heard a click, and the plane suddenly dropped its nose and went to a steep dive. For almost a minute the pilots tried to hold the steering wheel and level the plane. MD-83 550 dived at speeds of km / h. Pilots from all the forces pulling the wheel itself, and they were able to time raise the nose. To keep the aircraft in a horizontal position, the pilots decided to use the elevator. This mobile panel located in the rear, which is connected by wires to the controls. The pilots pulled them over. The fate of the aircraft depended on the strength of their muscles. Inside, immediately rose panic. Passengers do not know what happened to the plane. Meanwhile, the crew tried to adjust the speed of the aircraft to be able to land.


Expert: They were very experienced pilots, but the situation is more complicated. It became clear that a disaster could happen.


            The plane was heading to Los Angeles to make an emergency landing there. For some time the situation stabilized, and the pilots asked the dispatcher to give them space above and below the plane. They wanted to find out the cause of the problem.


aircraft maintenance 1


            The pilots understood that they were faced with a very serious problem. The situation worsened as they needed to decline, and the reaction of the aircraft to their actions was unpredictable. They contacted the ground service again and asked for help.


Judge: Well, when it is possible to contact with the ground by the technical service which has the necessary references. In addition, the technical service to obtain advice from the manufacturer. However, they are not always able to offer any assistance.


            Unfortunately, the technical service could not understand the danger of the situation. The pilots received no practical help from them. In fact, they were left alone with a failed stabilizer of the aircraft.


            The pilots tried to calm the frightened passengers and informed them that within 20-30 minutes they would land in Los Angeles. Unfortunately, it never happened. The crisis that began on board ended in a terrible disaster.


            The crew tried to play it safe. The pilots asked the dispatcher to give them the path to the bay. They needed to stay above the water until they took control of the control. Time and again they pulled the stabilizer switches, hoping that it would work. But all their attempts to rectify the situation were unsuccessful.


            The 261 board was already preparing for boarding for Los Angeles, as if something had knocked at the tail end. The plane again strongly lowered its nose. They began to stone fall from a height of 5500 meters. The plane turned over. He was thrown from side to side, but the pilots still tried to get him out of the dive.


Expert: They drove the plane even upside down and believed that they would succeed. 


            After seconds 60 261 terrible dive aboard crashed into the Pacific Ocean at the speed of 400 km / h.


            Aircraft MaintenanceSoon on the scene of the accident rescue helicopters arrived, but there was no one to save. The plane crashed into pieces. The crew and passengers were killed 88. Investigation of the disaster began immediately, but the wreckage lying at a depth of 200 meters.


Expert: During the operation of raising the wreckage, we used a special vessel equipped with scanning radars.


            When the black boxes were found, the National Transport Safety Committee (NTSB) began a study of the recording of cockpit talks.


Expert: We immediately realized that the problem was in the tail section of the plane of the deceased. It was there and it was necessary to find the cause of this terrible disaster.


            Airliner MD-83 at that time was in great demand. Around the world, more 2000 aircraft have flown. A feature of their design was that they had a T-shaped tail. The horizontal plane on the vertical stabilizer ensured the balance of the aircraft in the air. On a specific MD-83 model, an automatic screw jack located in the tail was used. He moved the horizontal stabilizer up and down. When the stabilizer was moving up, the nose dropped. And when the stabilizer was moving down, the nose of the plane was raised. This device was very reliable.


            What was the role of the screw jack 70 centimeters long in the tragedy of the 261 flight? It was necessary to raise it from the bottom of the ocean.


Expert: We are very surprised when they inspected the wreckage. Jackscrew was threaded into the coupling. He was lying on his own. Coupling jackscrew and are spaced from each other. It is not clear how a jack which is to be screwed into the sleeve, turned away from it. We have also discovered that the thread inside the sleeve was nearly erased and its remnants are wound on the screw thread of the jack. It was more than enough.


            Since the thread inside the coupling was erased, the jack was idling. The pilots could not understand the essence of the problem. There was no answer in any directory. It just never happened. Even when the pilots realized that the problem lay in the tail end of the aircraft, they did not know what they needed to do. The crew included two alternate engine jackHowever, all their efforts only aggravated the situation.


Expert: Their mistake was that they included both engines at once. And primary and secondary.


            When the pilots turned on two engines at once, the screw jack began to rotate. However, it only erased the remnants of the thread, but had no effect on the stabilizer. The plane was doomed. Under the influence of aerodynamic loads, the jack is completely out of order. No one, even the most experienced pilot, could do anything in this situation. The locknut could no longer hold the jack in place. After a while, she broke down.


Expert: When the lock nut is broken, the horizontal stabilizer completely out of order, and the aircraft became uncontrollable.


            Without a stabilizer, the aircraft's nose sloped down, and soon they entered a deadly peak. Nothing depended on the pilots. The experts were absolutely confident that a faulty screw jack It was the cause of the crash bead 261. Investigators asked the following question: why is it broken?


          aircraft maintenance 2  Finding out the cause of the malfunction, the investigators noticed that there was practically no lubrication on the jack. This fact made the experts very wary, and they reported this to the US Civil Aviation Authority. Those in turn ordered to check all the aircraft MD-83. An amazing discovery was made. It turned out that at Alaska Airlines on 6 from 34 airplanes this node was in the same condition as on the dead liner.


Expert: Lack of lubrication - That's the reason. That is what led to the fact that the screw thread has worn off.


            Thus, the simple lack of lubrication cost the lives of all the passengers of flight 261. Attention experts focused on how to carry out repair and maintenance work in the airline. Soon the scandalous facts were revealed.


Investigator: We talked to all the mechanics who worked in "Alaska Airlines". They said that they often had to write false reports about the work performed. In fact, no one performed them. 


            All the mechanics said that the authorities neglected their recommendations. In fact, the planes were sent to the flight without proper repair. Alaska Airlines was a successful company, but the crisis at the beginning of 90's affected everyone. Then the management reduced the prices of air tickets. But this situation is also reflected in the graph. aircraft maintenance.


Illiterate aircraft maintenance It led to the tragedy.


            In October 1998, one of the airline's mechanics filed a complaint with the US Civil Aviation Authority against Alaska Airlines. He described in detail the state of affairs with aircraft repairs. A year before the disaster, Alaska Airlines received a state check. services. They confiscated company documentation that related to aircraft repairs. However, no serious punishment followed. The company was able to convince the inspection authorities that the repair and aircraft maintenance were carried out properly. On the company was fined. And then disaster struck. As shown on the records of the deceased liner service, He already 2 years needed to replace a screw jack. This replacement has not been performed.


            The experts continued to investigate the causes of the crash of the 261 flight and made some more discoveries. When the company reduced ticket prices, it significantly increased the intervals between repairs. This was unacceptable, since every knot and every detail has a certain service life. Incorrect aircraft maintenance and led to the accident flight 261.


Judge: If the plane flies 600 hours without inspection - it is a lot. During this time, can wear away the grease and metal parts will wear. But if the range is 2000-2500 hours, as it was in "Alaska Airlines"- This will inevitably lead to disaster. It happened with the flight 261.


            In the final report, NTSB concluded that Alaska Airlines did not timely replace the screw jack of the horizontal stabilizer on an MD-83 aircraft. In the pursuit of profit safety of passengers was in last place. The investigation also revealed deficiencies in the structure of the aircraft itself. Malfunction of one node caused the death of the entire aircraft.


            Relatives of the victims hope that the airlines and manufacturers will draw the necessary conclusions and there will be no more such tragedies.


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