If the mechanical and electrical equipment (main propulsion device, main power supply, emergency power supply, boiler, steering device) fails in the process of entering and leaving the port and channel with heavy water traffic, the ship's maneuvering will be limited, and it is very easy to cause dangerous accidents.
Since April 7, the Maritime Safety Administration of the Ministry of Transport has carried out a nationwide special action to prevent the failure of ship mechanical and electrical equipment, focusing on reducing the risk of ship mechanical and electrical equipment failure, and focusing on preventing and curbing water traffic accidents.
Some of the cases in the special action are representative and worthy of our reference. Below, the editor introduces a recently discovered case of the failure of the host coding speed measurement system, and analyzes the hidden dangers related to the ME EFI host control system of the ship exposed by the case, hoping to arouse the vigilance and attention of relevant shipping companies and ships, draw inferences from one another, and strengthen investigation and self-correction.
The ME EFI host coding speed measurement system is faulty
01
Lesson
In February 2024, when a large container ship "C" berthed at the wharf, at the front of the wharf, the dual sets of ME EFI host coding and velocity measurement systems failed, resulting in the loss of control of the host and posing a threat to the safety of the wharf and the ship. The local maritime authorities immediately activated the emergency response and adopted measures such as tugboat towing in time to save the day.
02
The teacher of the future
After the analysis and research of the previous cases, the PSCO of the maritime department has strengthened its attention to the relevant situation of the ME EFI host coded speed measurement system in the recent PSC inspection. In April 2024, PSCO carried out a special inspection on the prevention of mechanical and electrical equipment failures of a large container ship "M" in conjunction with port state supervision and inspection. Similar to the "C" wheel, the wheel also uses ME EFI host, PSCO focused on the preventive inspection of the encoded velociome system of the main engine, and found that the encoded velociome system A system of the main engine was unusable due to the failure of the probe.
PSCO immediately issued a defect and asked the ship to correct it before sailing, but the crew in charge was still lucky, believing that there was still a host code speed measurement B system available, and wanted to correct it at the next port. PSCO immediately publicized the case, and the responsible crew expressed their understanding and promised to make a thorough correction before sailing.
Vital coded speed measurement system
Taking the above-mentioned "M" wheel as an example, the ME host coded speed measurement system of this wheel adopts the common free end installation method of the main engine crankshaft. It consists of two hollow shaft angle encoders (Angle Encoder A, Angle Encoder B) coaxially mounted at the free end of the crankshaft, a reference probe mounted on a disc wheel, and two signal amplification boxes (TSA-A and TSA-B). Taking system A as an example, the marking probe MMA in system A is triggered by the zero position of the first cylinder TDC, and the MSA is triggered when 90° after the TDC of the first cylinder detects the angle of the crankshaft of the main engine; the Q1A and Q2A phase contrast probes detect the speed and steering of the main engine, and the generated signal is processed by TSA-A and transmitted to the ECU and each CCU. Since system B does not have a reference probe (to provide a calibration signal), system A is generally used under normal circumstances, and system B is used as a backup.
The ME EFI host coded speed measurement system detects the role of the main engine steering, the speed of the main engine, and the angle of the crankshaft of the main engine, which is very important for ECUs and CCUs to control the timing of each cylinder of the main engine, judge the various actions of the diesel engine, accurately control the operation of the diesel engine according to relevant instructions, and realize a series of operations such as the main engine reversing/starting/exhausting/stopping. When both Tacho systems fail, the diesel engine will shut down.
Security management recommendations
ME EFI main engine has been widely used on ships. For the problems and failures encountered in the operation of the ME EFI host, it is recommended that the relevant shipping companies, ships and responsible crew pay enough attention to this, reasonably formulate maintenance plans in combination with the instructions of the main engine, and do a good job in fault prevention;
Source: Yangshan Port Maritime Safety Bureau
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