PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Air Traffic Control Fully Certified
Aircraft Equipment Problem Critical
Air Traffic Control Issued New Clearance; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Declared Emergency
Aircraft
During departure from Runway XXR while in the upwind; aircraft X reported that they had lost their engine and were making a turn back to the airport to land. They were given the wind and cleared to land on Runway YYL. I declared an emergency on their behalf and notified the Ground Controller to contact ARFF. I also notified the Supervisor. They landed without further incident and reported that their engine was running; but barely. They were able to taxi clear of the runway and back to the ramp.
Tower Controller described an ATC declared emergency event when departing traffic advised ATC of a lost engine and was handled accordingly.