Fatigue cracks in aircraft fuselage: sources, detection, and prevention

[enger]

what are fatigue cracks?
what are the major sources of fatigue withing the fuselage?
how can fatigue cracks be detected during inspection?
how can the risk of fatigue cracks in the fuselage be reduced?
why are they dangerous?
what is their origin?

I've tried to find answers for these questions about fatigue cracks but couldn't find anything on google

 

[SteamKing]

You can find more information at the following link:
http://en.wikipedia.org/wiki/Metal_fatigue