Calendar time

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Anonymous (not verified)
Calendar time

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?

Edited by: tourtelier_d on 13/05/2014 - 13:50
JMC (not verified)
Re: Calendar time

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"

Re: Calendar time

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.