(4) Machinery factors: cases where defects or problems exist in machinery and equipment as a result of human error at the design or manufacturing stage.
For cases of failures or malfunctions which were thought to have been the result of human errors, the probable causes (in terms of the characteristics of each process and environmental factors) were classified in terms of the four different factor types described above, and are shown in Table 3. The table shows that failures and malfunctions caused by problems in management systems accounted for about 40% of the total number of cases, while work characteristics and environmental factors account for 30%, Personal factors account for 20%, and human error related machinery factors represented less than 10% of the total number of cases. It can thus be seen from the Table.3 that about 70% of failures and malfunctions in engine rooms occurred either due to problems with the work management system or work characteristics and environmental conditions, and that problems arising from human-related machinery and equipment, and problems from personal factors are not nearly as prevalent.
