This is a great question. My impression is that the extension is a 1 year extension of your current scholarship, meaning it should be possible. If no one here gets you a response and the answer isn't online somewhere there's no shame in reaching out to a local detachment NCO who will get you an answer or get you to a person who could give you answer. Also I don't think it's every tech major, there is a list of 5 year approved majors from the SAF (Secratary of the Air Force), I can't happen to find it right now but that will tell you if you're eligible. If you are a 5 year major because of 1 year of co-op then I don't think you need approval as the Air Force does not pay for anything during Co-op except for a stipend if you are a tech major.