HISTORY OF FLIGHTOn February 1, 2024, about 1907 eastern standard time, a Beech V35B airplane, N6659L, was destroyed when it impacted two residences and the ground near Clearwater, Florida. The commercial pilot and two occupants of one residence were fatally injured, and one occupant of the other residence sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to FAA ADS-B data and air traffic control audio information, the flight departed about 1809 from Vero Beach Municipal Airport (VRB), Vero Beach, Florida, on an IFR flight plan destined for Clearwater Air Park (CLW), Clearwater, Florida. Night visual meteorological conditions prevailed at CLW and in the vicinity of the accident site. While en route, the pilot established contact with several FAA air traffic control facilities as the flight proceeded. At 1856:26, while the flight was at 3,800 ft pressure altitude, the pilot was in contact with the West Arrival/Departure combined with Satellite sector of the Tampa Air Traffic Control Tower (TPA ATCT West Arrival/Departure). The controller instructed the pilot to descend and maintain 2,600 ft above mean sea level (msl), which the pilot acknowledged. At 1857:32, the pilot requested a left turn to align with runway 34 at CLW, which the controller approved. At 1859:21, the flight was about 5 nm east-southeast of CLW at 1,400 ft pressure altitude when the controller advised the pilot that CLW was about the pilot’s 2 o’clock position and 5 miles. The pilot advised the controller that he was looking for the airport, then advised the controller that he needed to switch radio frequencies to the CLW CTAF to activate the pilot-controlled runway lights. The controller subsequently advised that there was no traffic between the flight’s position and CLW. The pilot then cancelled the flight’s IFR clearance, and the controller terminated radar services, instructed the pilot to squawk VFR, and approved the frequency change. The flight continued southwest until about 1900, then it turned right and proceeded west-northwest. About 1902, when the flight was less than 2 nm southeast of CLW, it turned right and proceeded northwest, generally toward CLW but west of the runway 34 extended centerline. Between about 1903 and 1903:30, the flight continued northwest, flying about 0.5 nm west of CLW and nearly parallel to runway 34, then continuing past the airport as it proceeded northwest. Beginning about 1903:46, the flight turned left (to the west, away from CLW), completed a 180° turn, proceeded generally south (flying about 2 nm west of CLW), then continued south past the airport. Two individuals who were in the FBO at CLW and could hear the CTAF communications over a speaker reported that they heard the accident pilot ask to turn on the runway lights. (The CLW CTAF was not recorded, so the timing of the communications is unknown.) One of these individuals reported that he informed the pilot that the runway lights were on (at medium intensity from a previous pilot who had landed) but that the pilot called back and asked again to have the runway lights turned on. The individual said he went to the FBO’s very high frequency (VHF) transceiver and keyed the microphone seven times to turn the runway lights’ intensity to high, then again informed the pilot that the runway lights were on. The individual estimated that, about 25 seconds later, the accident pilot again requested that the runway lights be turned on then advised, “I have a fire.” Both individuals at the FBO and some pilots who were flying nearby heard the accident pilot’s “fire” report. One individual at CLW said that he asked the pilot to repeat what he said, but the pilot did not reply. One individual at CLW who saw the airplane maneuvering reported that he did not see an external fire on the airplane. According to the flight’s ADS-B data, about 1905:15, when the airplane was about 1.7 nm southwest from the center of CLW flying about 900 ft pressure altitude, a 7777 transponder code displayed, followed by a change several seconds later to 7700 (the emergency code). The flight continued southeast, turned left to the east, then turned right onto a east-southeast heading. At 1905:49, the flight was at 1,200 ft pressure altitude, and the pilot reestablished contact with the TPA ATCT West Arrival/Departure controller by stating “nine five lima,” then “coming to Albert Whitted, I can’t see the other airport.” Albert Whitted Airport (SPG) was located in St. Petersburg, Florida. The controller advised the pilot that the flight was 1 mile south of CLW and asked if he could turn to heading 180° and to maintain the present altitude. At 1906:15, the flight was at 1,500 ft pressure altitude (and about 1.7 nm south-southeast from the runway 34 displaced threshold at CLW) when the pilot made his last radio transmission, advising the controller, “I’m losing engine.” The controller asked the pilot if he could see the St Pete-Clearwater International Airport (PIE), St. Petersburg-Clearwater, Florida, which was 3 miles ahead of his position. The controller also advised that runways 18/36 were available at PIE. The ADS-B data reflected that, after the pilot’s last communication, the flight turned right and headed northeast, remaining about 1,500 ft pressure altitude until about 1906:41. After that time, the airplane continued in the same general direction while descending. The last ADS-B target was at 1906:55, when the airplane was located near several buildings, flying at 400 ft pressure altitude. The accident site was about 800 ft northeast of the last ADS-B target. Based on data downloaded from the airplane’s Appareo Stratus, between 1906:37 and 1906:58, the airplane’s descent rate increased from 297 fpm to a maximum of 5,836 fpm with a corresponding groundspeed increase from 79 to 120 kts. The accident site was about 224 ft from the last data point. At 1906:59, the pilot of another airplane who was flying at 2,500 ft msl near the accident site advised the controller that the accident airplane had gone down, “really hard and is in flames.” During a postaccident interview, that same pilot reported that, from his vantage point in the right seat, the accident airplane’s descent angle was between 30° and 40° in a steep nose-down attitude, which he described as “like an uncontrolled descent.” He added that, while the airplane was going away from him, he saw a “very bright light” descending very fast to impact. Another witness, who was a passenger in a car driving south on US Highway 19 about 1/4 mile south of Gulf to Bay Boulevard (about 1,600 ft northwest of the accident site and north of the final flightpath of the accident airplane), reported seeing a “fireball” or something on fire flying ahead of their position from the right to the left, or west to east. She did not hear any sound and did not realize at that time that what she saw was an airplane. She described the fire as a round fireball at the front of a white cone-shaped object. The airplane crashed in a densely populated residential community, striking two residences and one vehicle. Two other residences were damaged by the postcrash fire. An individual who was in the first impacted residence sustained a minor injury when he was struck in the right leg by a piece of the airplane. Two individuals in the second impacted residence sustained fatal injuries. The remains of the extensively heat-damaged and impact-fragmented wreckage were found primarily in the second impacted residence, and all wreckage was secured for further examination. PERSONNEL INFORMATIONReview of two provided pilot logbooks revealed the pilot’s first and last logged flights were March 14, 1994, and December 5, 2022, respectively. His total time and pilot-in-command time (as of the last logbook entry) were about 1,079 hours and 960 hours, respectively. The last logbook reflected that he passed a commercial check ride on March 16, 2022. An Aircraft Insurance Renewal application dated January 23, 2024, and unsigned by the accident pilot, showed that the pilot reported a total flight time of 1,218 hours. The pilot’s logbooks reflected no flights into or from CLW. According to an FBO employee who had worked at CLW for just under 1 year, the pilot called the FBO the day before the accident flight to provide his credit card information. The FBO employee stated that the accident pilot had never been to CLW before and that pilots have mentioned that the airport is hard to find. AIRCRAFT INFORMATIONAccording to the engine’s Type Certificate Data Sheet, its maximum continuous horsepower and rpm were 285 at 2,700 rpm. By design, the airplane’s fuel supply system forward of the firewall consisted of a flexible fuel hose attached at a fitting on the firewall routed to the inlet of the engine-driven fuel pump, a flexible (unmetered) fuel hose routed from the engine-driven fuel pump outlet to the metering valve, a flexible (metered) fuel hose routed up and on the right side of the engine from the metering valve outlet to the fuel manifold valve inlet, and fuel injector lines from the fuel manifold valve to fuel injector nozzles installed in each cylinder. The engine’s throttle body and attached metering valve were attached to about midpoint of the oil sump. The outlet fitting (for metered fuel) was on the bottom of the metering valve near the forward and right sides. A review of the airframe maintenance records revealed a factory rebuilt engine was installed on June 27, 2016. Since installation of the rebuilt engine, normal maintenance and inspections occurred. There was no specific entry regarding the flexible fuel hose (metered fuel) from the outlet of the metering valve to the inlet of the manifold valve. The airplane had accrued about 583 hours between the engine installation date and the last annual inspection entry dated November 13, 2023. The emergency procedures section of the Pilot’s Operating Handbook and FAA Approved Airplane Flight Manual (POH/AFM) included an “Engine Fire In Flight” checklist that specified that, for an in-flight engine fire, to pull the firewall air control on the outboard side of the left lower subpanel and turn off the fuel selector valve in preparation for a forced landing. The same section of the POH/AFM specified that, for an emergency descent, to place the throttle to idle, the propeller to high rpm, the landing gear down, and establish 154 kts. AIRPORT INFORMATIONAccording to the engine’s Type Certificate Data Sheet, its maximum continuous horsepower and rpm were 285 at 2,700 rpm. By design, the airplane’s fuel supply system forward of the firewall consisted of a flexible fuel hose attached at a fitting on the firewall routed to the inlet of the engine-driven fuel pump, a flexible (unmetered) fuel hose routed from the engine-driven fuel pump outlet to the metering valve, a flexible (metered) fuel hose routed up and on the right side of the engine from the metering valve outlet to the fuel manifold valve inlet, and fuel injector lines from the fuel manifold valve to fuel injector nozzles installed in each cylinder. The engine’s throttle body and attached metering valve were attached to about midpoint of the oil sump. The outlet fitting (for metered fuel) was on the bottom of the metering valve near the forward and right sides. A review of the airframe maintenance records revealed a factory rebuilt engine was installed on June 27, 2016. Since installation of the rebuilt engine, normal maintenance and inspections occurred. There was no specific entry regarding the flexible fuel hose (metered fuel) from the outlet of the metering valve to the inlet of the manifold valve. The airplane had accrued about 583 hours between the engine installation date and the last annual inspection entry dated November 13, 2023. The emergency procedures section of the Pilot’s Operating Handbook and FAA Approved Airplane Flight Manual (POH/AFM) included an “Engine Fire In Flight” checklist that specified that, for an in-flight engine fire, to pull the firewall air control on the outboard side of the left lower subpanel and turn off the fuel selector valve in preparation for a forced landing. The same section of the POH/AFM specified that, for an emergency descent, to place the throttle to idle, the propeller to high rpm, the landing gear down, and establish 154 kts. WRECKAGE AND IMPACT INFORMATIONExamination of the accident site revealed evidence consistent with the airplane’s initial impact being on the roof of a residence. A portion of the right-wing fuel tip tank was found on top of the residence, while fragments from the same tank and a navigation and strobe light were found inside the residence. The roof exhibited a tear that was oriented on a magnetic heading of 075°. The main wreckage, consisting of the cockpit, cabin, wings, and engine assembly, came to rest upright on a magnetic heading of 164° among debris of a second residence, which was destroyed by impact and the postcrash fire. Pieces of wreckage were also noted in the street immediately adjacent to the main wreckage. The tailcone, which was the farthest piece from the main wreckage, was located about 84 ft east of the main wreckage. Examination of the separated tailcone revealed no evidence of soot on the interior or exterior. Examination of the wreckage revealed the cockpit, cabin, both wings, and the empennage were nearly destroyed by the postcrash fire. The fuel selector valve, which was found loose in the wreckage, showed impact and thermal damage and was positioned between the left and right fuel tank inlet ports. Only small sections of both wings were recovered. Examination of the engine revealed that only a portion of the engine crankcase, the top portions of the Nos. 3 and 5 cylinders, one propeller blade, one loose magneto, and ignition leads were visible. A section of plywood that was burned on the top side (in relation to the ground) was found above or near the Nos. 2, 4, and 6 cylinders. Unburned areas were noted on the bottom side of the plywood after turning it over. Dirt, which surrounded the engine, was carefully removed along with debris that was near or covering the engine. The top engine cowling was destroyed by the postcrash fire. The nose cowling and left and right side panels exhibited impact and fire damage and were crushed against the engine. The propeller was separated from the engine, and the crankshaft flange was fractured and missing about half of its diameter. Examination of the flight controls for roll, pitch, and yaw revealed no evidence of preimpact failure or malfunction. Both flap drive cables were located, but each flap actuator was not identified. The pitch trim tab actuator housing assembly, bellcrank, and pulleys located in the tail were consumed by the postcrash fire; there was no evidence of failure or malfunction of the intact portions of the pitch trim system. The cockpit was extensively impact- and fire-damaged, and examination revealed the throttle control was 0.7 inch from full in, the mixture control was full rich, and the propeller control was 0.4 inch from full in. Avionics, flight and engine instruments sustained heavy fire and impact damage. Removal of the engine side panels and nose cowling pieces revealed dirt on the interior surface of the cowling pieces. Examination of the engine oil sump revealed that the very forward portion was relatively free of soot and did not exhibit fire damage, while the left side above the mounting location of the throttle body and metering valve exhibited dark soot. The right side of the oil sump above the forward portion of the throttle body also exhibited dark soot. The bottom, right side, and left side of the oil sump, as well as the area aft of the mounting location of the throttle body and attached metering valve, showed white discoloration. Removal of the oil sump revealed dirt inside consistent with impact damage. The forward portion of the sump gasket showed normal color. From about the midpoint of the sump aft, the gasket showed extensive heat damage. Examination of the drivetrain, air induction, ignition, exhaust, and lubrication systems of the engine revealed no evidence of preimpact failure or malfunction. Examination of the throttle body and metering valve revealed it was impact separated and sustained heat damage, but the throttle and mixture control cables and hoses remained attached. The throttle control was wide open, and the mixture control was 1/8 inch from the full rich stop. Fuel supply hoses were continuous from the firewall fitting to the inlet fitting of the engine-driven fuel pump, to the fuel metering valve, and to the inlet fitting of the manifold valve. Impact fracture of fuel supply fittings were noted on the inlet of the engine-driven fuel pump and the inlet and outlet fittings at the fuel metering valve. All but one b-nut of each fuel supply hose in the engine compartment were tight at their respective fittings (including fittings that were fractured); the exception was the b-nut at the outlet of the fuel metering valve, which was 1.25 flats from being finger tight (the hexagonal b-nut has six flat sides used to engage with a wrench). An NTSB Materials Laboratory examination of the metered fuel hose from the fuel metering valve outlet to the inlet of the manifold valve and the fractured outlet fitting of metering valve by the NTSB Materials Laboratory revealed that about the last 3 inches of fire sleeve on the fuel metering valve end of the hose exhibited thermal damage that consumed the rubberized coating of the fire sleeve. The fracture surface of the fitting exhibited deformation and slant fractures consistent with bending overstress. The threads on both the b-nut of the hose that connected with the outlet fitting and the threads of the fractured fitting from the outlet of the metering valve did not exhibit any evidence of cross threading or other anomaly. Following examination, the hose b-nut and the flared end of the fractured fitting were assembled and torqued to 136-inch pounds, which was about the minimum specified torque value for a b-nut with a steel fitting. After torquing, the connection appeared solid and fully seated. MEDICAL AND PATHOLOGICAL INFORMATIONA postmortem examination of the pilot was performed by the District Six Medical Examiner’s Office. The pilot’s cause of death was blunt trauma, and the manner of death was accident. Toxicology testing performed by the FAA’s Forensic Services Laboratory on the pilot’s cavity blood, heart, kidney, liver, lung, muscle, spleen and vitreous specimens identified no evidence of impairing drugs. The result was negative for carboxyhemoglobin, which had a reporting cutoff of 10%. The documented glucose level in vitreous was not considered abnormal. TESTS AND RESEARCHA NTSB Sound Spectrum study was performed on recorded audio captured during times when the pilot had the microphone keyed but was not talking with FAA air traffic control, which occurred near the end of the flight at 1847:55, 1905:51, and 1906:15. During the first two times, the engine rpm was about 2,450. At the last instance, which was the pilot’s last transmission about 43 seconds before impact, the engine speed was about 2,500 rpm. Multiple videos captured by cameras at businesses west of the accident site depicted a light descending steeply with sounds associated with engine operation, followed by a fireball. NTSB analysis of the sound in the videos determined that, during the last 5 seconds before ground contact, the accident airplane’s engine speed was calculated to be 2,053 rpm. One impacted vehicle in the driveway immediately adjacent to the main impacted residence displayed two parallel slash marks, one on the trunk and one on the left rear portion near the side panel. The distance between the center of the slashes measured 2.125 ft. Further review of the site revealed the angle between the edge of the roof immediately adjacent to the main impact crater and the ground near the main impact was 22.7°. The angle between the initial impact point on the top of the roof and the ground was not determined. Using a propeller slash formula, based on the distance between the slashes and the accident airplane’s ground speed of 120 kts immediately before impact, the engine rpm was calculated to be about 1,907. Using the descent angle of 22.7°, the same number of propeller blades, and an engine rpm of about 1,907, the calculated airspeed was about 130 kts.