On May 14, 1999, approximately 1330 central daylight time, a Cessna 177 airplane, N2343Y, was substantially damaged during impact with trees and terrain while maneuvering following a partial loss of engine power near Roanoke, Texas. The student pilot and one passenger were seriously injured, and the other passenger was not injured. The airplane was registered to and operated by the pilot. Visual meteorological conditions prevailed, and a VFR flight plan was filed for the 14 Code of Federal Regulations Part 91 cross-country flight. The accident occurred as the flight was originating from the Northwest Regional Airport, for a destination of Tucson, Arizona, with a planned fuel stop at Deming, New Mexico. The pilot stated that "pre takeoff checks were completed and all indications were normal." During takeoff climb from runway 17, about 200-250 feet agl, the engine started "stuttering." The engine rpm and airspeed started decreasing, so he lowered the nose to gain airspeed; however, the airspeed did not increase. He "put the plane into level flight" and "reduced flaps to attempt to gain airspeed." The airspeed and engine rpm did not increase. The pilot further reported that he performed a magneto check, which resulted in no change in engine operation. He then turned on the carburetor heat, and after noting no change in engine performance, turned it off. Due to trees in front of the aircraft, he elected to turn left. He established the best glide airspeed and continued turning left to downwind. Prior to impacting a tree, he "pulled back [the] power" and turned off the master switch. The aircraft came to rest amongst the trees. A witness reported that he and another person observed the aircraft takeoff. The other person made the comment, "it would be better if he pushed in the throttle." He stated that the engine sounded "smooth, but not at full power." Examination of the airplane revealed that the fuselage was twisted, the engine was displaced downward, and the tip of the right wing was separated. An examination of the engine revealed that the left and right magnetos "appeared" to be timed to 25 degrees before TDC (top dead center); however, the left magneto had an erratic timing light indication. The left magneto was sent to the manufacturer for further examination. The carburetor was removed from the engine and examined. During the examination the float valve would stick in the seat assembly and could not be displaced by using low pressure air. The carburetor was sent to the manufacturer for further examination. A teardown examination of the Precision MA-4SPA carburetor, serial number A-10-11065, was conducted at the Precision Airmotive facility in Everett, Washington, on June 22, 1999, under the supervision of the NTSB. Clearance between the needle and float with clip was found to be about .080 inches, which according to Precision, "means the clip would not open the valve." "Excessive" play was found where the accelerator pump shaft passes through the throttlebody. The accelerator pump discharge check valve was found failed. Some reddish, granular contamination was found in the bowl and accelerator pump well. An examination of the Slick 4251R magneto, serial number 4070210, was conducted at the Unison Industries Slick Aircraft Products facility in Rockford, Illinois, on September 10, 1999, under the supervision of the NTSB. During the functional examination, the magneto was operated to simulate engine idle, 550 to 750 rpm. The output on leads #1 and #3 exhibited a sporadic non-spark event, while the output on leads #2 and #4 was normal. The magneto was operated at 1,700 rpm to simulate the rpm specified in the Cessna Pilot Operating Handbook (POH) for preflight run-up and engine/magneto performance check. The #3 lead exhibited a sporadic non-spark event. The magneto was run a 2,750 rpm to simulate the maximum sea level rpm of the engine. The #3 lead exhibited a sporadic non-spark event. During the internal examination, the contact point setting was found to be 0.006 inches. The acceptable range for the point gap for a Slick magneto properly timed is 0.008 inches to 0.012 inches. The contact points and cam exhibited "significant" wear. "Significant corrosion (rust) was noted on the rotor shaft, rotor shaft laminations, frame laminations, internal hardware, and impulse coupling." The magneto and carburetor were released to the owner on December 3, 1999; however, the owner of the aircraft did not return a signed wreckage release.