HISTORY OF FLIGHT On August 29, 2017, about 1920 central daylight time, a Grumman AA-1B, N8866L, was substantially damaged when it impacted trees and terrain while approaching Portland Municipal Airport (1M5), Portland, Tennessee. The private pilot and passenger were fatally injured. The airplane was owned and operated by the pilot in accordance with the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the local personal flight. The flight originated from 1M5 about 1831. A student pilot, who was the pilot's grandson, flew the airplane 2 days before the accident flight. The student pilot stated that he completely fueled the airplane that day and then flew to Gallatin, Tennessee, to pick up his flight instructor for training. They flew for about 1.4 hours that day. The student pilot stated that the pilot did not purchase fuel before his accident flight, and no one else flew the airplane between the two flights. Several witnesses reported seeing the airplane as it flew "low" shortly before the accident. They generally described that after it contacted the treetops it impacted the ground in a nose-down attitude. A Garmin 196 GPS was recovered from the wreckage and sent to the National Transportation Safety Board Vehicle Recorders Laboratory for data download. Review of the data revealed that the airplane departed 1M5, flew south, and circled the city of Gallatin, Tennessee, before returning to 1M5. The last recorded position was about 0.5 miles south of the threshold of runway 1. According to the data, the duration of the accident flight was 0.83 hour. PERSONNEL INFORMATION According to Federal Aviation Administration (FAA) records, the pilot held a private pilot certificate with an airplane single-engine land rating. He held an FAA third-class medical certificate issued September 23, 2015, limited by a requirement to have available glasses for near vision. At the time of the medical examination, the pilot reported 450 total hours of flight experience. The pilot's logbook was not recovered. AIRCRAFT INFORMATION The airplane was issued an airworthiness certificate on October 20, 1976. According to the FAA type certificate data sheet for the Grumman AA-1B, the airplane was originally equipped with a 108-horsepower Lycoming O-235-C2C engine driving a two-bladed McCauley 1A105 SCM 7157 propeller. The engine had been replaced with a 150-horsepower Lycoming O-320-A2B engine driving a two-bladed Sensenich 74DM6-0-60 propeller. According to FAA registration records, the pilot purchased the airplane on September 2, 2014. According to the airplane's maintenance logbooks, the last annual inspection was completed on November 11, 2016. At that time, the airframe had accumulated a total time of 1,744.5 hours; the engine total time was 2,722.5 hours with 522.5 hours since overhaul. At the time of the accident, the recorded tachometer time was 1,786.4 hours. The airframe maintenance logbook available for review was labeled "Book #2 Feb. 1999." The first page in this logbook indicated that the airplane was equipped with a Lycoming O-320-A2B engine. It is unknown when the O-235-C2C engine was removed and the O-320-A2B engine installed. An updated pilot operating handbook or operating handbook supplement that would have provided fuel consumption figures for the higher horsepower engine was not located. A review of the Grumman American AA-1B Owner's Manual revealed that the airplane held 22 gallons of useable fuel. When equipped with the original O-235-L2C engine, the airplane consumed 5.3 gallons of fuel per hour at 2,500 ft and 64% cruise power, and the fuel endurance at this altitude and power setting was 3.9 hours. The Lycoming Operations Manual for the O-320-series engine stated that the engine consumed 10 gallons of fuel per hour at 75% rated power settings and 8.8 gallons per hour at 65% rated power settings. METEOROLOGICAL INFORMATION At 1953, the recorded weather at Bowling Green-Warren County Regional Airport (BWG), located 23 miles north of the accident site, included wind calm, visibility 10 statute miles, and scattered clouds at 4,600 ft. WRECKAGE AND IMPACT INFORMATION The accident site was about 2,500 ft from the threshold of runway 1 and 200 ft to the left of the runway centerline. The debris path was about 200 ft long from initial impact with 60-ft-tall trees to the main wreckage on a heading of 060° magnetic. A ground scar consistent with the engine and propeller was observed about 85 ft from the initial tree strike. The airplane came to rest upright on the landing gear on a heading of 240° magnetic. Flight control continuity was established to all flight controls. The right wing separated and came to rest beside the main wreckage. The right fuel tank was crushed, and the fuel cap was missing. The right fuel tank appeared to be breached; however, there was no fuel odor or browning of vegetation. The left wing remained attached to the fuselage. The flap and aileron remained attached to the wing and were intact. The fuel tank was intact and not breeched. There was no fuel in the left tank. The fuel drain line was opened, and no fuel was present in the lines. The fuel selector valve was in the left tank detent. The electric boost pump filter was removed, and less than 1 teaspoon of fuel was captured. The mixture and throttle controls were full forward. The fuselage and cockpit were substantially damaged. The canopy was shattered except for the sliding rails mounted on the fuselage. The seat belts were intact, and the pilot's seat belts were still connected. The passenger's seat belts were not connected, and there were no tears or stretch marks in the belt webbing. The engine remained attached the fuselage. The engine was removed and placed on a lift for examination and partial disassembly. The top spark plugs were removed, and the engine was rotated by hand. Thumb compression was achieved on all cylinders. Continuity was established between the crankshaft to the rear gears and to the valvetrain. The cylinders were examined using a borescope, and no anomalies were noted. The propeller remained attached to the engine, however the propeller flange was fractured. One propeller blade was bent aft, and the spinner dome was crushed and fragmented. Neither of the propeller blades exhibited leading edge gouging or chordwise scratching. The examination of the wreckage did not reveal evidence of any preimpact mechanical malfunctions. MEDICAL AND PATHOLOGICAL INFORMAITON The Office of the Medical Examiner, Nashville, Tennessee, performed an autopsy on the pilot. The report listed the cause of death as multiple blunt force injuries. The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed forensic toxicology on specimens from the pilot. Citalopram was detected in urine and blood (0.411 µg/ml); N-Desmethylcitalopram was detected in urine and blood (0.083 µg/ml); and Verapamil and norverapamil were detected in the urine and blood. Citalopram is an antidepressant medication also marketed with the name Celexa; N-Desmethylcitalopram is a metabolite of citalopram. Although not considered impairing by itself, the use of citalopram by pilots requires a special issuance medical certificate because the underlying depression can cause cognitive impairments. The pilot did not report the use of citalopram to the FAA at the time of his last medical examination. Verapamil is a prescription blood pressure medication that is not considered impairing. Norverapamil is a metabolite of verapamil.