Assume that an engineering system can fail due to a maintenance error caused by factors such as poor equipment design, inadequate training, poor work environment, use of deficient maintenance manuals or inadequate work tools. Two major factors for poor equipment design are oversight or no formal consideration of the occurrence of maintenance error. The no formal consideration of the occurrence of maintenance error can be caused by either no requirement in design specifications or insufficient allocated funds. Two important factors for poor work environment are inadequate lighting and inaccessibility. Similarly, two main causes for the use of deficient maintenance manuals are unavailability of compatible maintenance manuals or poorly written maintenance procedures.

a) Based on the above information, develop the fault tree diagram for the top event Engineering system failed due to maintenance error with appropriate logic symbols and event names.

b) Assume the probability of occurrence of all the base events are all 0.02. Calculate the probability of the top event Engineering system failed due to maintenance error.