Is my necrosis healing normally after my lipo & tummy tuck procedure? (Photo)

Thank you for sharing your question and photograph.  After 4.5 weeks it appears that the area of necrosis is starting to pull away from your surrounding tissue and may start to slough. With the degree of involvement I would advocate for surgical removal by your surgeon to help speed the healing process.  The area of darkness is likely shadowing as more necrosis will not develop this far out from surgery.  Hope this helps.

It appears you have a significant sized area of necrosis along the incision. It is reasonable to allow the area to demarcate and heal. It appears that you may have some additional fat underneath the black necrosis that also needs debridement. 
I think surgical debridement would expose healthy tissue that would allow the area to heal faster with good wound care. Talk to your surgeon about your options, as you probably will need a scar revision in the future.

Each surgeon has their own ways of trading this necrosis issue. I think I would decried the black areas surgically. Than continue the silvadene cream regime. Either way the healing will take up to 6 more months in my over the internet opinion.