"The FAA's special condition ultimately required Boeing to prove that the chance of a Dreamliner crash from a lightning strike was "extremely improbable", defined as one catastrophic failure in every one billion flight hours, a one-in-a-billion chance...."
http://www.aljazeera.com/news/2016/06/flawed-faa-redactions-expose-boeing-787-whistleblower-160612123344752.html
-vk-