On September 9, 2012, approximately 1500 central daylight time, a Piper PA-28RT-201 single-engine airplane, N2878V, sustained substantial damage when it ditched into a lake following a partial loss of engine power near Gilmer, Texas. The student pilot, who was the sole occupant, was not injured. The airplane was registered to AirLease Nevada, LLC, and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as an instructional solo flight. Visual meteorological conditions prevailed and a flight plan was not filed. The flight originated from Fox Stephens Field (JXI), Gilmer, Texas, at 1400. The student pilot stated he was practicing basic flight maneuvers in preparation to take his private pilot check ride. During a 20 degree bank turn at 1,500 feet above ground level, the engine backfired and lost partial power. The pilot attempted to regain engine power; however, his attempts were unsuccessful. The pilot could not maintain altitude, and due to the tree covered terrain surrounding the area, he elected to ditch the airplane into a lake. The airplane landed in the water and sank. The pilot was able to egress and was rescued by nearby boaters. A review of the maintenance records revealed the Lycoming IO-360-C1C6 (serial number RL 28998-51A) engine, underwent its most recent annual inspection on October 11, 2011, at a total time of 1,011.7 hours since major overhaul. During the inspection, no abnormal engine discrepancies were noted. At the time of the accident, the engine had accumulated 1,043.2 hours since major overhaul. On January 30, 2013, the engine was examined by the NTSB investigator-in-charge and a representative from Lycoming engines. Examination of the engine revealed the No. 3 cylinder had little to no compression when the engine crankshaft was rotated by hand. The No. 3 cylinder was removed, and the piston displayed excessive exhaust blow-by and the piston rings were seized in the ring lands. The No. 3 fuel injector nozzle was removed and found partially blocked with debris. The magnetos were functionally tested and no anomalies were noted. The spark plugs were functionally tested and no anomalies were noted. The intake box to fuel control air hose displayed black discoloration consistent with engine backfire. The cockpit mixture control lever was found in the mid-range position.