On August 1, 2000, at 1000 central daylight time, a Romero Sea Rey, homebuilt experimental amphibious airplane, N817R, sustained substantial damage when it impacted the water at Lake Keystone, approximately 15 nautical miles west of Tulsa, Oklahoma. The airplane was owned and operated by private individuals under 14 Code of Federal Regulations Part 91. The commercial pilot, sole occupant, received serious injuries. Visual meteorological conditions prevailed for the local personal flight, and a flight plan was not filed. The flight departed the Richard Lloyd Jones Jr Airport, Tulsa, Oklahoma, at 0845. On the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), the pilot reported her intentions to fly over and around Lake Keystone with no intentions for landing. The pilot reported that she had retracted the landing gear following the departure from Tulsa. She remembered the airplane was configured at a power setting of 4,800 rpm and the airspeed of 75 mph, with 10 degrees of flaps extended for the flight. The airplane was at an altitude of 1,100 to 1,200 msl. The pilot further stated that "I blacked out," and that she had, "no pre-warning of impending danger physical or otherwise." Local authorities reported that the airplane was found intact and floating upside down in water approximately 7 to 10 feet deep, and it "appeared that the main landing gear was extended." The pilot completed dual flight training in Florida in the same make/model of aircraft. The FAA airworthiness certificate was issued for the airplane on April 4, 2000. The pilot had accumulated a total of 28 flight hours in the aircraft. The pilot held a second class medical certificate, issued December 23, 1999, at the time of the accident. The following information was extracted by the NTSB Medical Officer from medical records maintained on the pilot by the FAA Civil Aeromedical Institute Aeromedical Certification Division and from personal medical records supplied by the pilot. The pilot was diagnosed with an abnormal heart rhythm in 1987. By May 1990, following a full cardiac workup, the pilot was placed on medication. In August 1990, the pilot applied for a third-class medical. The pilot's physician(s) reported to the FAA that the pilot's PSVT (paroxysmal superventricular tachycardia) was under control with medication. In a letter submitted to the FAA, one of the physicians wrote that the heart condition "would not handicap her in any way in the operation of an airplane." The pilot was issued an FAA third-class medical certificate in November 1990, and an FAA second-class medical certificate in 1994. Each time a medical certificate was issued, the pilot's eligibility letter from the FAA stated that the pilot's operation of an aircraft was prohibited any time new symptoms or changes occurred, or if the pilot experienced side effects or required a change in medication. The pilot had several episodes of atrial fibrillation that were not reported to the FAA. In 1996, the pilot did not report to the FAA an episode of a sudden loss of vision in one eye, which was attributed to cardiac embolization secondary to PSVT. Following the loss of vision, she was prescribed Coumadin (a blood thinner). The pilot continued to experience episodes of paroxysmal atrial fibrillation. The use of Coumadin was not reported to the FAA. Emergency room records, following the accident, said "she [pilot] is supposed to be on Coumadin, but she refuses to take it." The pilot demonstrated "intermittent atrial fibrillation, rapid ventricular response during the hospitalization." In a letter to the NTSB Medical Officer dated February 22, 2001, the pilot stated "I would always have warning when an episode of atrial fibrillation would be coming on. Of course I never flew when I had any symptoms, nor did I have any symptoms the day of the accident."