She can wade through this database, assuming he was Army Air Corps. WWII Army Enlistments 1939-1946 http://aad.archives.gov/aad/series-list.jsp?cat=WR26http://aad.archives.gov/aad/series-list.jsp?cat=WR26 Couple I see are from Arkansas but enlisted in other states. Some are white, some are African American.
Ancestry has a couple of WWII Death and Casualities databases. I find a several James Butler and James R. Butler.They are listed with either place enlisted or next of kin residence. Couple are Navy so possible from Navy carrier but no reference to Arkansas,There is one James Robert Butler with next of kin, a wife, and livng in Nebraska.
It would realy help her to post parents names, wife's name, if married, and at least year of birth. Siblings names would also be a help. Was he the pilot or crew. She should look at the newspaper of the time where her grandfather and or his parents lived for any news item or obituary.
The NARA has service records, but sadly they had a fire and 80% of Army/Air Corps WWII records were burned, Navy and Marine were not affected. So your friend could still try but again she would need to know for sure what service branch, date of birth and service number would be a big help. The death databases have those numbers on Ancestry, she might try her local county or college library to see if they have Ancestry to use.
Also I have seen done reseach where the men used their middle name to enlist and/or a middle inital is also incorrect for name, no matter which one is used. With WWII typewriters and carbon copies an R can be transcribed as a B by the time it gets on an online database.