# Risk Assessment of Lift-Jacking Accidents Using FFTA-FMEA
## 4 Results
### Fuzzy Fault Tree Quantitative Analysis  
The probability importance coefficient \(I_{p(X_{i})}\) and the relative probability importance coefficient \(I_{c(X_{i})}\) were calculated for each BE according to Equations (2) and (3) respectively, as shown in Table 11.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Serial** & **Probability** & **Serial** & **Probability** & **Serial** & **Probability** \\
**Number** & **Probability** & **Number** & **Probability** & **Number** & **Probability** \\ \hline X\({}_{1}\) & 0.0014 & X\({}_{10}\) & 0.002 & X\({}_{19}\) & 0.009 \\ X\({}_{2}\) & 0.0068 & X\({}_{11}\) & 0.0023 & X\({}_{20}\) & 0.03 \\ X\({}_{3}\) & 0.0029 & X\({}_{12}\) & 0.0036 & X\({}_{21}\) & 0.0083 \\ X\({}_{4}\) & 0.0008 & X\({}_{13}\) & 0.0015 & X\({}_{22}\) & 0.011 \\ X\({}_{5}\) & 0.03 & X\({}_{14}\) & 0.021 & & \\ X\({}_{6}\) & 0.018 & X\({}_{15}\) & 0.0036 & & \\ X\({}_{7}\) & 0.03 & X\({}_{16}\) & 0.0083 & & \\ X\({}_{8}\) & 0.0064 & X\({}_{17}\) & 0.0071 & & \\ X\({}_{9}\) & 0.0036 & X\({}_{18}\) & 0.0023 & & \\ \hline \hline \end{tabular}
\end{table}
Table 10: Fuzzy failure probability.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**BE** & **Serial** & **Structural** & **Probability** & **Relative** \\
**Number** & **Importance** & **Indicator** & **Importance** & **Importance** \\  & & **Indicator** & **Indicator** & **Indicator** \\ \hline Severe wear of traction sheave grooves & X\({}_{2}\) & 0.123 & 0.00847 & 0.571 \\ Oil stains in traction sheave grooves, wire ropes & X\({}_{3}\) & 0.123 & 0.00863 & 0.242 \\ Severe wear of the traction wire rope and reduction & X\({}_{1}\) & 0.123 & 0.00862 & 0.117 \\ in diameter & X\({}_{4}\) & 0.123 & 0.00861 & 0.0667 \\ Excessive tension on the traction ropes on both sides of the traction sheave & X\({}_{14}\) & 0.000451 & 0.00126 & 0.256 \\ Broken speed limiter wire rope & X\({}_{22}\) & 0.000451 & 0.00125 & 0.133 \\ Tensioner wheel groove wear & X\({}_{19}\) & 0.000451 & 0.00124 & 0.108 \\ Incorrect installation or improper adjustment of safety clamp & X\({}_{18}\) & 0.000451 & 0.00124 & 0.0275 \\ Oil on the surface of the slider/wedge & X\({}_{17}\) & 0.000451 & 0.00124 & 0.0854 \\ No synchronised action of the two wedges & X\({}_{16}\) & 0.000451 & 0.00124 & 0.0999 \\ The wedge is smoothed & X\({}_{15}\) & 0.000451 & 0.00124 & 0.0431 \\ Excessive wedge clearance & X\({}_{12}\) & 0.000451 & 0.00124 & 0.0431 \\ Damage to the speed limiter spring by prolonged expansion & X\({}_{12}\) & 0.000451 & 0.00124 & 0.0431 \\ and contraction & X\({}_{11}\) & 0.000451 & 0.00124 & 0.0275 \\ A loose nut on the speed adjustment area & X\({}_{10}\) & 0.000451 & 0.00124 & 0.0239 \\ Tensioner wheel groove wear & X\({}_{10}\) & 0.000451 & 0.00124 & 0.0999 \\ Short circuit in the safety circuit of the speed limiter & X\({}_{21}\) & 0.000451 & 0.00124 & 0.0179 \\ Oil stains on the surface of the speed limiter components & X\({}_{13}\) & 0.000451 & 0.00124 & 0.0179 \\ Stuck brake arm & X\({}_{7}\) & 0.0293 & 0.000838 & 0.244 \\ Severe wear of the brake wheel and brake tile & X\({}_{5}\) & 0.0293 & 0.000838 & 0.244 \\ The brake circuit is faulty, and voltage is always present & X\({}_{20}\) & 0.0293 & 0.000838 & 0.244 \\ Excessive clearance between brake wheel and shackle & X\({}_{6}\) & 0.0293 & 0.000828 & 0.144 \\ Oil on the surface of the brake wheel & X\({}_{8}\) & 0.0293 & 0.000818 & 0.0507 \\ Brake springs are too loosely adjusted & X\({}_{9}\) & 0.0293 & 0.000816 & 0.0284 \\ \hline \hline \end{tabular}
\end{table}
Table 11: Importance indicators of BEs.