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“The cause of the sudden turn, the possibility of the solenoid valve stuck is low
To the extent there is a disagreement, we will conclude through further investigation “
Investigation plan such as valve sticking point, equipment failure, etc.
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On the 25th, the Special Committee for Investigation into Social Disasters (Sacha Committee) announced the results of an experiment to verify the cause of the sudden change on the Sewol ferry at the new Mokpo port, Jeollanam-do. The committee said the result of an investigation was low on the possibility that the sharp turn to the right, which was considered one of the causes of the sinking, was related to the ‘sticking of the solenoid valve (electronic valve)’ . Revealed.
To find out the cause of the disaster, the SAC has investigated the cause of the sharp turn, the cause of the side slope (the ship is leaning towards the current side) and the cause of the rapid flooding. When the Sewol ferry sinking started from a starboard turn, a model of the Sewol ferry steering gear was manufactured and tested to determine the cause of the sudden turn.
Previously, three of the six members of the Sewol Hull Investigation Committee stated that the cause of the sudden turn to starboard was that the steering was out of control, such as the solenoid valve stuck and the rudder changed the angle to starboard. All three said that there are parts that cannot be explained only by internal factors, and that the possibility of an external force cannot be excluded.
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To achieve the same shape and performance as the Sewol ferry, the Sachaum Committee modeled the steering gear with the advice of the manufacturer, and then applied various scenarios to verify rudder movement. The experiment was carried out on the premise that the solenoid valve of the drive device to Incheon had become stuck.
The first condition was the use of a single driving device for Incheon. The helmsman headed to starboard 5 degrees and the solenoid valve stuck, the starboard angle of the rudder changed, the Sewol ferry turned to starboard, the steering device to Incheon and worked to Jeju, and the port angle of the helmsman changed to 8 degrees.
The second condition was the case that the two devices of Incheon and Jeju were operated at the same time. The head tube changed the angle to starboard and turned, and the solenoid valve of the driving device for Incheon stuck, the starboard angle of the rudder was changed, the Sewol ferry turned to starboard, and the head tube turned the port side at 8 degrees.
It was concluded that the first condition was unlikely as a result of the committee’s discussion. For the first condition to be possible, there must be an emergency action by the crews stopping the trips to Incheon and operating the trip to Jeju, but the crew has denied such an emergency so far.
Regarding the second condition, he explained that if the pilot changes the angle to starboard, a sudden turn could occur even during normal operation, regardless of the solenoid valve sticking.
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However, there were some opinions that the possibility of realizing the first condition is high. This is because the crews constantly claim that there was no steering action that changed the starboard angle, and in the breeding experiment, if the solenoid valve stuck during normal steering, the starboard angle change phenomenon was played repeatedly. The results of the reproducible experiment above are consistent with objective evidence, such as recorded images of the Sewol ferry black box and data from the Automatic Ship Identification System (AIS).
In light of these views, the Committee plans to further investigate the timing of the solenoid valve stuck from the driving device to Incheon, whether or not there was an intentional or negligent turn to starboard by the crew, and whether there was any action. of emergency.
/ Reporter Ji Woong-bae [email protected]
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