A Lead Mechanic reports a company B757-200 was pushed back from an adjacent gate and the Flight Crew proceeded to power-up to high power to get the aircraft moving; while turning the aircraft's engine exhaust back towards the gate area where an 'A' Check was being accomplished by Mechanics.

Narrative

While complying with an 'A' check on company aircraft on Gate 1 in ZZZ; one of our B757-200's on Gate 2 was being pushed back to taxi out. At this time the B757 proceeded to power up to high power to get it moving and continued to power up as the aircraft was turning to taxi out. At this time; Maintenance personnel realized that the B757 was turning the (engine) exhaust in their direction and they 'hung' onto whatever they could grab onto; to keep from being blown across the ramp. One Mechanic was on a yellow lift truck working on the APU. He had to hold on to the APU while the yellow lift truck was swaying back and forth. Also; there was a stand that was blown across the ramp. Mechanics inside the aircraft could feel the aircraft bounce up and down from the B757 aircraft exhaust. Fortunately no one was injured and no damage to aircraft or equipment occurred. This requires immediate attention as noted in description of events. Possible improper pushback. Pilots may have been unaware of Maintenance working next door. Possible improper taxi out. Mechanics notified the Lead Mechanic and Supervisor.Instruct Ground crew on pushback; (that) when Maintenance is being conducted and for pilots to be aware of their surroundings. This could have had a different ending.