No. Your phrase makes sense, but it has a different meaning.
"I am going back," is in simple present tense. --- I am returning (now).
"I am going to go back," is in simple future tense. -- I will return (later).
You need the phrase "subject [be] going to verb" in order to indicate future tense in English. The verb "[be]" must be conjugated to match the subject. The pattern is almost the same in Spanish, "subject [ir] a verb." The verb "[ir]" must be conjugated to match the subject.
Going implies motion toward something that is away from the speaker at the present time. For example, I am in my house," I am going to the store, do you need anything?"
Coming implies motion toward the current location. For example, I am at the store: "Please come to the store to bring my wallet. I left it with you."
Sorry for replying here, for some reason it won't let me reply to your last comment (seems like too many comments in the tree). I can't see how is that all contradictory to what I said since the beginning. "Voy a volver" is in a future tense and that is why "I am coming back" is not a correct translation, you seem to agree with me but keep saying I am wrong.
I think it's good that we both want exactitude in the meaning of words. This certainly isn't worth the expenditure our time. I agree with you that "Voy a volver" is future tense. The only point of departure would be the translation into English. "I am coming back " is the present tense, but can be used to express future intent. Wouldn't you agree?
I will return was accepted today 27/1 2016. I usually for shortness, translate both Spanish futures ( "ir + a + infinitive" and "verbstem + future endings" ) to "will + infinitive" in English and Duo accepts it. However I think that " to be going + infinitive" is a better translation, at least it is more similar to "ir+a+infinitive"
Many versions of Spanish pronounce V as B. http://www.spanishdict.com/answers/200752/how-to-pronounce-the-spanish-letter-v