Boeing 787 Planes Fail After 248 Days Of Being Powered On 

The Guardian:

The plane’s electrical generators fall into a failsafe mode if kept continuously powered on for 248 days. The 787 has four such main generator-control units that, if powered on at the same time, could fail simultaneously and cause a complete electrical shutdown.

Due to what appears to be an integer overflow bug, pilots will lose control of the planes after 248 days of being continuously powered on. The fix, literally, is to turn it off and on again before the 248 day mark hits. Typical of big-business timescales, Boeing are aware of the problem but the software fix won’t be released until the fourth quarter of the year.