Reinforcing split roof beams

[abarrie]

I was replacing the fascia boards near my roof and when I took one off I looked up and saw that all of the support beams for the roof had split, probably due to snow etc. The roof is still holding up OK and it may have been this way for a long time, no way to know. What is the best way to reinforce these without having to rip the (almost brand new) roof apart?
Thanks!
Alex

[HayZee518]

what size is the rafter? 2x6? 2x8? 2x10?