6. Structural improvement

Analysis of calculation of reliability indicators evaluation indicates that the lowest probability of non-failure work of system among the blocks has a block IV. Among the block units IV the lowest probability of non-failure work has a booster pump. The overall damage of this equipment are: overheating, failures in work, cavitation and other.

The activities, which are aimed at improving operating efficiency and reliability of the system may be:

• additional cleaning the fuel;

• changes in equipment design;

• diagnostic tools development

O ne way to improve the reliability of the system is the installation of additional pump ЭЦН-323 (Figure 5).

1_IV , 2_IV - booster pump; 3_IV - fine filter; 3_IV - relief valve fine filter;

Figure 5. Improvement of Block IV

Calculate the probability of Block IV improvements following formula:

P_IVim= 1 – {[1- (P_1IVP_3IV)][1- (P_2IVP_4IV)]}=

=1-{[1-(0,99704438*0,99852109)][1-(0,99704438*0,99808184)]}=0,9999784

P _(system)im = P_I P_II P_III P_IVim P_V= =0,9999967*0,99997955*0,999642*0,9999784*0,99744328=0,9970409

P_(system)im> P_system - probability of non-failure operation of system increased here follows that improvement takes place.

7. Algorithm development for detection of problem with functional system of the aircraft

For the cases in flight and during the ground engine testing of fuel supply the following algorithm is proposed, which is shown in Figure 6. The scheme includes all possible situations connected with the mentioned problem, and sequence of measures for solution taking into account priority of operating aggregates. Beginning of the algorithm is denoted by “S” – “Start”, its ending with “F” – “Finish”. Graph is to be read upside-down following the denotations which correspond to the occurred situation.

Figure 6 Algorithm for determining the damage

Conclusion

During the work of a course project was the analysis of failure of the fuel system of the Ty-154. Turned a least reliable unit IV, namely block element - pump. The main failures of this element are: overheating, refusal to work, work in cavitation conditions. To improve the reliability of the system was suggested to install an additional pump. Calculations show that after the installation of additional pump the probability of non-failure system operation increased.

Reference

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