A turbine engine combustor reliability goal is a B1 life of 1800 cycles or longer under service-like conditions. Success is defined as a combustor having no circumferential cracks longer than 20 inches (out of possible 53 inches). The number of cycles required to reach a 20-inch crack was known to follow a Weibull distribution with B-3.0. To demonstrate this reliability goal with 90% confidence:

a. How many combustors must be tested each can accumulate 7500 test cycles?

b. How many cycles must each accumulate if ten combustors were available for this reliability test?

c. Repeat part (a) and (b) for one failure test (failure-success test) and give your comments while comparing the results of success test and success-failure test.