ERA24FA104

An in-flight engine compartment fire due to a partially loose flexible fuel hose b-nut at the fuel metering unit. Contributing to the severity of the accident was the pilot’s inability to visually identify the destination airport at night, which prolonged the in-flight emergency.

The pilot proceeded toward the destination airport, cancelled his instrument flight rules (IFR) clearance when about 5 nautical miles (nm) from the airport, then proceeded under visual flight rules (VFR) in night visual weather conditions. The airport, with which the pilot was unfamiliar, was non-towered, located in a densely populated area, and not equipped with a rotating beacon. After establishing contact on the airport’s common traffic advisory frequency (CTAF), the pilot announced that he was unable to locate the airport and asked repeatedly for the pilot-controlled runway lights to be turned on. According to witnesses who were in the airport’s fixed based operator (FBO) facility and heard the CTAF communications, at the time of the pilot’s first request, the runway lights were already on medium intensity from an airplane that had just landed. One of the witnesses responded to the pilot’s request by keying the radio microphone seven times to turn the lights up to high intensity. The witnesses and pilots in a nearby airplane reported that they subsequently heard the pilot announce that he had a fire. One witness at the FBO asked the pilot to repeat what he said, but the pilot did not. ADS-B data showed that the flight had approached the airport from the southeast headed northwest. Once it reached the airport, it proceeded northwest, parallel to and about 0.5 nm west of the runway, before continuing northwest and past the airport. It subsequently turned left (to the west, away from the airport), completed a 180° turn, then again passed the airport before continuing south. About 2 minutes before the accident, the flight was flying about 900 ft pressure altitude, and the pilot set the transponder to emergency code 7700. The flight proceeded briefly east, then southeast. About 1 minute before the accident, the pilot reestablished contact with the air traffic controller at the facility with which he had previously canceled his IFR clearance. The pilot told the controller that he was proceeding to a different airport because he was unable to visually identify his original destination airport. The controller advised the pilot that the flight was 1 mile south of his original destination airport then asked the pilot if he could turn to a heading 180° and maintain the present altitude. The pilot advised the controller, “I’m losing engine.” According to a sound spectrum study, at the time of this communication, the airplane’s engine was operating at 2,500 rpm. The controller asked the pilot if he could see another airport that was 3 miles ahead of his position (and closer than the alternative airport that the pilot mentioned), but the pilot did not respond. The flight continued southeast, then turned left and descended steeply until impact. According to a review of the available data, during the airplane’s final 20-second descent, it attained a maximum descent rate of 5,836 ft per minute (fpm) and the groundspeed increased. Per the sound spectrum study, the engine rpm decreased to about 2,053 then was estimated to about 1,907 immediately before impact. Witnesses on the ground who saw the airplane’s descent reported seeing fire on the forward portion of the airplane. Although the engine rpm decreased immediately before impact, it could not be determined what the pilot meant when he advised the controller that he was losing the engine because, at that time, it was operating at 2,500 rpm, which was slightly below the maximum continuous takeoff propeller rpm. Postaccident examination of the flight controls and engine drivetrain, ignition, air induction, exhaust, and lubrication systems revealed no evidence of preimpact failure or malfunction. The outlet fitting of the metering valve was impact-fractured, and the b-nut of the flexible fuel hose attached to this outlet fitting was not fully tight. The throttle body and metering valve and corresponding area of the engine oil sump exhibited clean burn areas without soot deposits, though after coming to rest those areas were shielded by dirt and the upwardly crushed engine cowlings. No discrepancy with the threads of the flexible fuel hose or of the fractured outlet fitting at the metering valve was identified, and it was possible to successfully torque the b-nut to about the minimum specified value. Further, several other fuel fittings in the engine compartment were also impact-fractured (similar to the fractured outlet fitting), but their respective hoses’ b-nuts remained tightly secured. The engine was installed about 7.5 years before the accident, and there was no record of any maintenance done to the area of the loose b-nut since. The engine had accumulated 583 operating hours since installation, so it is unlikely that the hose was not tightly secured at that time. It is also unlikely that it was loosened by impact or the effects of the postcrash fire. It is more likely that, at some point after engine installation, undocumented maintenance occurred to the fuel hose from the metering valve to the manifold valve, and unknown maintenance personnel failed to adequately torque the fuel hose b-nut at the metering valve outlet fitting. Based on the severity of the observed thermal damage in the area of the throttle body and metering valve, the most likely fire scenario for the accident airplane was an in-flight fire occurring due to ignition of fuel leaking from the slightly loose fuel hose at the outlet of the fuel metering valve. The steep descent immediately before impact was the pilot’s likely response to the in-flight engine compartment fire and his initiation of an emergency descent. Though the position of the fuel selector valve was found between the left and right tank positions, and the position at impact could not be determined from the available evidence, the engine rpm about 43 seconds before impact was 2,500. Although the engine rpm had decreased immediately before impact, it is likely that the pilot did not promptly turn off the fuel selector in accordance with the “Engine Fire in Flight” checklist after recognizing and reporting a fire on the destination airport’s CTAF. Thus, had the pilot promptly secured the fuel selector valve and in conjunction with the steep descent, it is possible that the extent of the in-flight fire could have been mitigated. Further, had the pilot been able to visually locate the destination airport, it is likely that the he could have landed the airplane earlier in the accident sequence. The pilot had negative results for carboxyhemoglobin, and no pre-existing issue was found at autopsy. Thus, it is unlikely that any medical issue resulted in the pilot’s failure to arrest the airplane’s steep rate of descent before impact with the residences.

Review 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. According 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. A 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. On 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. Petersb