Maybe something like "servicing interval"? I think that is what they use to describe maintenance periods for vehicles.
Or calibration period, inspection period, etc?
No, I don't think he means that.
If I understand correctly he is talking about the period from when a device is send to maintenance, the max amount of time that the maintenance department has available to fix it, if it doesn't get fixer in that time-frame then it is considered junk.