Varying load using python scripting

Hi all

Am using python scripting to query nodal coordinates and then do some simple calculation on that. In cae model,  a surface is created. Using python scripting I want to track element faces under the created surface for further manipulations. 
mdb.models [''].rootAssembly.instaces[''].surfaces[''].elements
Using the above line am able to identify elements below the surface and extract nodes (not show here) as well. But how to identify the particular element face (as there are 3+ faces on each element) associated with the created surface ?

Regards
Arumugam