Template:Fix delays and test phase target mtbf

Fix Delays and Test Phase Target MTBF

Fix delays reflect how long it takes from the time a problem failure mode is discovered in testing, to the time the corrective action is incorporated into the system and reliability growth is realized. The consideration of the fix delay is often in terms of how much calendar time it takes to incorporate a corrective action fix after the problem is first seem. However, the impact of the delay on reliability growth is reflected in the average test time it takes between finding a problem failure mode and incorporating a corrective action. The fix delay is reflected in the actual idealized growth curve in terms of test time. In other words, the average fix delay is calendar time converted to test hours. For example, say that we expect an average fix delay of two weeks: if in two weeks the total test time is 1000 hours, the average fix delay is 1000 hours. If in the same two weeks the total test time is 2000 hours (maybe there are more units available or more shifts) then the average fix delay is 2000 hours.
There can be a constant fix delay across all test phases or, as a practical matter, each test phase can have a different fix delay time. In practice, the fix delay will generally be constant over a particular test phase. [math]\displaystyle{ {{L}_{i}} }[/math] denotes the fix delay for phase [math]\displaystyle{ i=1,...,P, }[/math] where [math]\displaystyle{ P }[/math] is the total number of phases in the test. RGA 7 allows for a maximum of seven test phases.