[Yo-Yo]

Heat and humidity was cited for the very high failure rate of missiles in Vietnam.

You’d think that 40 years later we’d come up with a way to combat humidity in a missile.

[MasterGunner01]

We had to deal with the obsolescence of electronic parts in the commercial world all the time. Mil-Spec parts usually have commercial equivalents, but the commercials have higher failure rates and looser tolerances than Mil-Spec.

That said, the logistics people have to look at failure rates of key components. If re-engineering the component is not possible or a replacement cannot be found, then the supply people will have to do a final, one time buy of that part or parts. The one time buy is a guesstimate of usage and failures over the next 20-25 years. Once procured, that's all there is for spare parts in the bin.