Hello, I′m new, couldn′t find an answer to my very basic question, so I place it here. Am I right in thinking that FIDES calculates MTBF in units of calendar hours rather than the operating hours defined in the phase(s) of a mission profile? If so, and if I want an MTBF in operating hours, I presumably need to multiply the reported MTBF by operating hours/8760 (assuming my mission profile has that total), right?
Yes, Scotty, you are fully right!
FIDES methodology take in count all the life of the electronic in its environment, even when not powered or stored as a spare.
So if you wish to consider only a certain period of its life (such as "operating hours"), you need to multiply the reported MTBF by your ratio.
You well understood the basic FIDES principles.
Note: This discussion could take place better in the other heading of this forum, called "Missiion profile setup"
The basic calculation to have a "mission failure rate" is as follow :
Lambda_mission = Lambda_calendar * calendar_duration / mission_duration
Where :
-calendar_duration is 8760 hours for a year
-mission_duration is the total mission time in the calendar_duration.
Don′t forget that by doing so the mission failure rate (Lambda_mission) take also into account the failure rate of non-mission phase.
Taking the failure rate specific to an unique environmental condition is also possible but this should be made cautiously.