Originally Posted by
tdracer
Turns out there is another brilliant engineering design decision that's forcing further postponement. The Launch Termination System electrical system is completely independent of the rest of the launch systems electronics (for good reason). As a result, it's battery powered.
So far, so good. Rational system design.
Not so rational - the battery is life limited, with a maximum of 25 days from installation to when it needs to be serviced (just increased from 20 days in the last couple weeks) -
and it's not serviceable on the pad 
. So once the launch system leaves the Vehicle Assembly Building, they only have 25 days to launch it, or it needs to be returned to the VAB. That is simply horrible engineering - the sort of thing a first year engineering student would know better. $4 Billion plus per launch, and they couldn't be bothered to provision the Launch Termination System to be serviceable on the pad
.
Comment elsewhere (Robert Pearlman on spacecollect forum) on this that the roll back to the VAB in part is due to the need "to meet the requirement by the Eastern Range for the certification on the flight termination system" (sic):
I haven't looked any further but this be a temporary requirement that was imposed by the USAF rather than something should (or perhaps could) have been foreseen at the design stage.