On the other hand it is confirmed by the redundant model shown in Fig.3-1A and 1B that the failure rate could increase from λ1=0.856 [occ./1000Hr] of M1 to λ2=1.48 [occ,/1000Hr] of M2 for main propulsive power system and for generating one from single to quadruple one λ1, λ2, λ3, λ4=0.22, 0.44, 0.83, 1.51 [occ./1000Hr] of G1, G2, G3, G4 respectively. It should be noticed that the average failure rate λi of each failure is approximately propotional to the number of redundant system for the power systems of propulsive (Mi) and generating engines (Gi).
On concerning with emergency maintenance works on board their avegage man-hour mh would be recognized to be about 1.5 〜 3 times of those of all failures (nhd1/mh1), for both the single system and redundant ones and for propulsive and generating power engines sets shown in Table 4-1A and 1B.
With respect to the dependability which has the two meanings of both reliability and maintainability the manning index MI (= λ × mh; equation 4-1) of emergency work would decrease depending the decreacing of values of failure rate λ except two cases of redundant system, parallel and triple engine sets G2 , G3 of generating power system shown in Table4-1B.
Finally it is noticed that this paper is the first report concerning with redundant model and emergency troubles required the harder maintenace manpower of maintainability, where the average man-hour had to require more man-power of 18.3 [MH/occ.] (mhTd; MdT) than 10.2 [MH/occ.] (mhT; MT) and more man-power of 14.2 [MH/occ.] (mhTd; GdT) than 5.62 [MH/occ.] (mhT; GT).
7. ACKNOWLEDGEMENT
The authors thank Mr. Taku Takemura and Mis. Yumi Iwai for their lots of works and helps in Kobe University of Mercantile Marine.
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