Equation $7-2$ defined availability in terms of mean time between failure $($MTBF$)$ and mean time to repair $($MTTR$).$ To what extent are design teams responsible for these two parameters? To what extent are front$-$liners and maintenance associates responsible?

A control valve for a fuel supply system has an average failure rate of one failure per three years. Suppose the fuel supply system is to be used on an upcoming space mission that will last two weeks.

a$.$ Is this part of the vehicle safe envugh? $($Calculate value of reliability at mission end.$)$

b$.$ What might be done to improve reliabilty of this, or any other, component?