I need to know if a felon can work in law enforcement

Normally no, there can be a few exceptions. In TN for example because they were hired by a family member, there were a couple on the Highway Patrol there.

And the exact crime may make a difference, how long it has been and more. For example some departments have a strict rule, any drug use, convicted or not, will kick you out,

Also no one with a domestic violence change can be a law enforcement since it effects your ability to carry a weapon.

So unless you have some connections, and unless you don't mind working at small departments with low pay and no benefits, I would say another line of work would be best.

Can a felon work in aviation below wing, i.e. marshal a plane, load cargo etc