Section 2 Failure Mode and Effects Analysis (FMEA)

2.1.1 An FMEA is to be carried out in accordance with Pt 5, Ch 22, 2.1 General 2.1.2 to Pt 5, Ch 22, 2.1 General 2.1.7 for the propulsion systems, electrical power supply systems and steering systems to demonstrate that a single failure in active equipment or loss of an associated sub-system, see Pt 5, Ch 22, 1.1 General 1.1.3, will not cause loss of all propulsion and/or steering capability as required by a class notation. Typical sub-systems include associated control and monitoring arrangements, data communications, power supplies (electrical, hydraulic or pneumatic), fuel, lubricating, cooling, etc.

2.1.2 The FMEA is to be carried out using the format presented in Table 22.2.1 Failure Mode and Effects Analysis or an equivalent format that addresses the same safety issues. Analyses in accordance with IEC 60812, Analysis techniques for system reliability – Procedure for failure mode and effects analysis (FMEA) or IMO MSC Resolution 36(63) Annex 4 – Procedures for Failure Mode and Effects Analysis, would be acceptable.

2.1.3 The FMEA is to be organised in terms of equipment and function. The effects of item failures at a stated level and at higher levels are to be analysed to determine the effects on the system as a whole. Actions for mitigation are to be determined.

2.1.4 The FMEA is to:

1. identify the equipment or sub-system, mode of operation and the equipment;

2. identify potential failure modes and their causes;

3. evaluate the effects on the system of each failure mode;

4. identify measures for reducing the risks associated with each failure mode; and

5. identify trials and testing necessary to prove conclusions.

2.1.5 At sub-system level it is acceptable, for the purpose of these Rules, to consider failure of equipment items and their functions, e.g. failure of a pump to produce flow or pressure head. It is not required that the failure of components within that pump be analysed. In addition, their failure need only be dealt with as a cause of failure of the pump.

2.1.6 Where FMEA is used for consideration of systems that depend on software-based functions for control or co-ordination, the analysis is to investigate failure of the functions rather than a specific analysis of the software code itself.

2.1.7 The FMEA is to establish that in the event of a single failure:

1. for PSMR and PSMR notations, that the ship will retain not less than 50 per cent of the installed prime mover capacity and not less than 50 per cent of the installed propulsion systems and retain steering capability;

2. for PMR and PMR notations, that the ship will retain not less than 50 per cent of the installed prime mover capacity and not less than 50 per cent of the installed propulsion systems;

3. for SMR and SMR notations, that the steering capability remains available;

4. for PSMRL notation, that the ship will retain the ability to use available installed prime mover capacity and installed propulsion systems that are not directly affected by the failure and retain steering capability at a service speed of not less than seven knots; and

5. for PMRL notation, that the ship will retain the ability to use available installed prime mover capacity and installed propulsion systems that are not directly affected by the failure.