HISTORY OF FLIGHT On August 04, 2006, about 1030 central daylight time, a single-engine Cessna A188B agricultural airplane, N86188, was substantially damaged during impact with water following a loss of control while maneuvering near Sumrall, Mississippi. The commercial pilot, sole occupant of the airplane, was fatally injured. The airplane was registered to and operated by S&S Aviation of Collins, Mississippi. Visual meteorological conditions prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 137 aerial application flight. The local flight originated from a private airstrip approximately 1005. There were two witnesses to the accident. According to the witnesses, the pilot finished spraying a field and had given them a thumb's up signal before flying in an easterly direction at an approximately altitude of 300-feet above ground level (AGL). One witness reported that when the airplane was about three-fourths of a mile from their location, he heard the engine "pop as it would if the mixture was too lean." The engine then sounded as if it "cleared up" and moments later the airplane turned back to the west. The witness added that, as the airplane proceeded back towards him, he observed the engine running; however, it did not appear to be operating at "full throttle." The witness further reported that when the airplane was approximately 150 AGL, the airplane turned to the south before it "plunged" nose-first into a pond. The other witness reported similar observations and added that as the airplane turned south, the airplane "lost airspeed and nosed-down into the lake." PERSONNEL INFORMATION The pilot held a commercial pilot certificate with ratings for airplane single-engine land. His last Federal Aviation Administration (FAA) third-class medical certificate was issued on June 15, 2006, with the limitation of "Holder must possess glasses for near and intermediate vision." The pilot's logbooks were not recovered during the course of the investigation. The pilot reported on his most recent medical application that he has accumulated a total time of 1,525-flight hours. AIRCRAFT INFORMATION The 1975-model Cessna A188B, serial number 18802008T, was a low wing semi-monocoque tail-wheel equipped-airplane, configured for one occupant. The airplane was powered by a direct drive, horizontally opposed, fuel injected, air-cooled, six-cylinder engine. The engine was a Continental IO-520-D, serial number 293161R, rated at 300 horsepower at 2,850 rpm, and was driving a two-bladed constant speed McCauley propeller. According to the airplane's owner, the airplane's most recent annual inspection was completed in April 2006, at an airframe total time of 8,030 hours. METEOROLOGICAL INFORMATION At 0953, the weather observation facility at Bobby L Chain Municipal Airport (HBG), near Hattiesburg, Mississippi, located 12 nautical miles east from the site of the accident, was reporting the wind from 350 degrees at 6 knots, visibility 8 statute miles, clear of clouds, temperature 88 degrees Fahrenheit, dew point 72 degrees Fahrenheit, and barometric pressure setting of 30.06 inches of Mercury. WRECKAGE AND IMPACT INFORMATION The wreckage was found submerged in a farm pond surrounded by rolling terrain. Once recovered, on-site documentation of the wreckage was conducted by investigators from the Federal Aviation Administration, Cessna Aircraft Company, and Teledyne Continental Motors. According to investigators, all major components of the airplane were accounted for at the site, and control continuity was established to the airplane's flight controls. The leading edges of the left and right wing were found crush aft in a manner consistent with a near vertical descent. An examination of the engine was performed. A liquid consistent with aviation fuel was located in the fuel line between the fuel metering unit and the fuel manifold. The throttle and mixture controls were found connected and free to move. The fuel pump coupler was found intact. The top spark plugs were removed and the engine crankshaft rotated. Thumb compression was established in each cylinder with the exception of number four. An examination of the number four cylinder via a borescope revealed that the number four piston did not move when the crankshaft was rotated. The engine was then recovered to the facilities of Teledyne Continental Motors of Mobile, Alabama, for further examination. A teardown examination of the engine was performed under the supervision of an NTSB representative. The examination revealed that the crankshaft, connecting rods and connecting rod bearings exhibited thermal and mechanical damage consistent with a lack of lubrication. The number four connecting rod bolt was found completely fractured. The number three piston head exhibited signatures of an exhaust valve impact, and the number three exhaust push rod was found bent. The oil sump, which had not been compromised during the accident, was found to contain residual oil. Investigators could not determine the reason for the loss of engine oil. MEDICAL AND PATHOLOGICAL INFORMATION The Chief Medical Examiner of Rankin County, located in Pearl, Mississippi, performed an autopsy on the pilot, on August 4, 2006. The FAA, Toxicology Accident Research Laboratory, located in Oklahoma City, Oklahoma, conducted toxicological testing on the pilot. ADDITIONAL INFORMATION The wreckage was released on April 3, 2007, to a representative of the owner's insurance company.