There is no simple answer to this question. "Felony" is a term from civilian law, now, in the US referring to a crime with a sentence of over 1 year. AWOL is a status related to Desertion, which is a crime under military law.
The lease severe form is "Failure to report." This, alone, would not be a felony.
A.W.O.L., (being absent without leave0 if not resolved within a month, or if done with an intention not to return, is desertion. Penalty for desertion depends on circumstance, and can be severe, matching a civilian felony conviction. But it is not always so severe.
I got this info from http://en.wikipedia.org/wiki/AWOL#Absence_without_... but a lawyer familiar with Army justice would be the best source.