Boeing 787s must be turned off and on every 51 days

[Luc Lion]

Originally Posted by DaveReidUK

A common tick counter period in real-time systems is 1.024 ms (don't ask me why!). That works out at 50.9 days.

Thanks Dave.
I forgot that most modern CPUs are clocked to give a reliable 1 microsecond interval.
That means that an interrupt coded to click every millisecond is actually triggered every 2^10 microseconds or 1.024 millisecond.
That is the reason.