Kerrville, TX, USA
N501CE
Beech 58
The pilot was conducting an instrument flight rules (IFR) flight in a twin-engine airplane with five passengers. During a GPS approach to the destination airport, both engines lost total power within 10 seconds of each other; the left engine regained near full power about 40 seconds later, which it maintained until the end of recorded data. As the pilot continued the approach, he did not ensure the flaps were up or feather the propeller of the inoperative right engine, which was contrary to the airplane manufacturer's emergency procedures guidance. As the airplane descended with the right engine inoperative below the cloud ceiling to about 500 ft agl, its flightpath leveled and airspeed decreased below the minimum controllable airspeed (Vmc). The airplane's continued flight profile below Vmc with the unfeathered propeller of the inoperative right engine, the left engine near full power, and the airplane's aft center of gravity resulted in a right-turning spin and ground impact. The pilot's filed flight plan indicated a minimum fuel load required of 58 gallons, although this did not account for the instrument approach and alternate airports. However, the pilot's flight planning log indicated only 50 or 54 gallons of fuel onboard. Thus, based solely on the pilot's logs, there was insufficient fuel onboard the airplane to embark on the flight. Because the airplane was beyond its maximum gross weight with just 50 gallons of fuel onboard, it is likely that the pilot did not want to add additional fuel. Thus, the pilot's decision to depart on the accident flight without adequate fuel onboard showed poor judgement. Although the pilot departed without an adequate fuel reserve for the IFR flight, an actual fuel load of 50 or 54 gallons would have been sufficient to reach the destination airport (the airplane burned about 42 gallons just before the crash site about 6 miles from the airport). However, when the airplane was fueled at the pilot's request 8 days (five flights) before the accident flight, it was not completely filled. Because the pilot was not present for the fueling and did not crosscheck the fuel receipt with his fuel-planning logs, he did not recognize that the error meant he had less than 50 gallons of fuel onboard before departing on the accident flight. As evidenced by the close correlation between the pilot's fuel logs and the engine data monitoring (EDM) fuel consumption data for the accident flight and the five flights before it, the pilot mainly relied on EDM data to determine the quantity of fuel onboard the airplane. Thus, the fueling error introduced 8 days before the accident was carried through the pilot's planning logs for the next six flights, including the accident flight. Further review of the accident airplane's fueling records, the pilot's flight-planning logs, and fuel consumption data from the EDM revealed that the airplane actually had about 12 gallons less fuel than the pilot indicated in his fuel log for the accident flight. Thus, the lack of sufficient fuel for the accident flight resulted in the airplane's engine power loss during the approach. In addition, the abnormally high resistances in both fuel quantity transmitters would have caused the cockpit fuel quantity indicators for both wings to read about 5 gallons higher each than the actual fuel present, corresponding to an additional 1/16th tank on each of the indicators. Thus, because of the high resistances in both fuel quantity transmitters, the pilot's belief that 50 (or 54) gallons of fuel were onboard at takeoff (rather than the actual fuel level of 38 gallons) may have been corroborated by the fuel quantity indicators; however, the effect of the inaccurate indications on the pilot's actions are uncertain. The pilot's autopsy indicated he had severe coronary artery disease, which placed him at increased risk of a sudden cardiac event. However, the accident sequence was not consistent with acute pilot impairment or incapacitation as recorded data indicate that the pilot was controlling the airplane up until the airplane dropped below its minimum controllable airspeed, so it is unlikely that the pilot's coronary artery disease or any sudden medical event contributed to this accident. In summary, multiple errors before takeoff led to a loss of engine power due to fuel exhaustion. The pilot did not accurately record the amount of fuel added after fueling, the pilot did not verify the amount of fuel onboard the airplane, the fuel quantity transmitters did not accurately indicate the amount of fuel onboard, and the pilot decided to take off with inadequate fuel to conduct the IFR flight in an overweight airplane. Lastly, during the flight, once the right engine lost power, the pilot failed to properly configure the airplane per the manufacturer's emergency procedures guidance and allowed the airspeed to drop below the point at which the airplane could maintain flight.
HISTORY OF FLIGHTOn April 22, 2019, at 0851 central daylight time, a Beech 58 airplane, N501CE, was substantially damaged when it was involved in an accident near Kerrville Municipal Airport (ERV), Kerrville, Texas. The pilot and five passengers died. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 business flight. According to airport surveillance video from West Houston Airport (IWS), Houston, Texas, the pilot accomplished an abbreviated preflight inspection of the airplane, during which he appeared to visually check the exterior left-wing fuel level sight gauge but not the right-wing fuel level sight gauge; the pilot did not sump any of the 10 fuel drains. The pilot returned to the terminal to meet the passengers, and after both engines were started, the airplane departed about 0730. According to air traffic control (ATC) and automatic dependent surveillance-broadcast (ADS-B) information, after departing IWS, the pilot obtained an instrument flight rules (IFR) clearance and was instructed to climb to 3,000 ft mean sea level (msl). The flight proceeded toward ERV, climbing to a cruise altitude of 6,000 ft msl. About 0824, the pilot requested the RNAV (GPS) instrument approach for runway 12 and was cleared for the approach via a procedure turn and to descend to 4,000 ft. About 0833, the pilot reported his descent to 4,000 ft and the controller advised that "bases were 2,400," which the pilot acknowledged. About 0839, the pilot was cleared for the GPS instrument approach to runway 12 and instructed to maintain 4,000 ft to the initial fix for the approach (OBUCO) (see figure 1). Once the airplane was in-bound to the airport, about 0843, the controller directed the pilot to switch to the ERV advisory frequency, which was unmonitored. The GPS instrument approach profile for runway 12 included a descent to 3,300 ft msl at 5.3 nautical miles from the runway. Figure 1. A Google Earth aerial view of terrain near the accident site with overlaid ADS-B data and approach information. According to ADS-B data, the airplane maintained an altitude of 3,900 ft until about 0844:59, when it began a steady descent; the airplane was about 13 miles from the runway. Data from the airplane's engine data monitor (EDM) indicate that the left engine lost power about 0845 followed by the right engine about 10 seconds later. ADS-B data indicated that the airplane steadily descended well below the approach profile. EDM data indicated that, about 40 seconds after losing power, the left engine regained near full power, which it maintained until the end of recorded EDM data about 0851. ADS-B data indicated that the airplane slowed below the minimum controllable airspeed (Vmc) of 83 knots as it descended from about 500 to 300 ft agl, and the descent rate decreased. A witness on the ground saw the airplane on final approach at a low altitude, when it entered a right turn, began a right spiral, and disappeared behind a ridge line. PERSONNEL INFORMATIONA flight instructor who frequently flew with the pilot and conducted his most recent flight review stated the pilot's mechanical flying skills were very good but, on occasion, his understanding of technical issues was not as strong. The flight instructor noticed a few times when the pilot did not perform well during unexpected in-flight issues. He stated the pilot normally planned to land with at least 1 hour of fuel remaining. AIRCRAFT INFORMATIONFuel System The airplane's fuel system comprised three fuel cells and one wet tip tank for each wing. Total fuel capacity for the airplane was 200 gallons; the three fuel cells in each wing held a total of 83 gallons of usable fuel and 3 gallons of unusable fuel, and the wet tip tank held 14 gallons of fuel, all of which was usable. The wing fuel cells and wet tip tanks were interconnected so that all usable fuel was available with the fuel selector valve for each wing in the ON position and supplying fuel to its respective engine. The CROSSFEED position on the fuel selector was only to be used in an emergency. Each wing had two flush-type fuel filler caps: one located in the outboard end of each outboard leading-edge fuel cell and one in the wet tip fuel tank. Fuel quantity was measured by float-type units that electrically transmitted a single indication for each wing system to fuel quantity indicators in the cockpit. The fuel quantity indicator would show full until the respective wing fuel cells contained less than about 75 gallons. According to an American Bonanza Society (ABS) technical representative, the three fuel quantity transmitters in each wing were wired in series with one another. Fuel quantity would be at least 75 gallons at 199 ohms and 3 gallons of unusable fuel at 0 ohms. In this range, the resistance value of the transmitter circuits in each wing was designed to be directly proportional to the amount of fuel. The caution range (yellow band) on the cockpit fuel quantity indicators was from 0 to 1/8th of the amount indicated by the fuel quantity indicator (about 9.33 gallons usable per wing). Fuel level sight gauges on the leading edge of each wing only indicated fuel levels from 40 to 60 gallons per wing. It was not possible to use a dipstick to check fuel quantity due to each wing's dihedral and the location of the filler caps. Fueling Information Fueling of an exemplar 1999 Beech 58 showed that when the airplane's wing fuel cells were filled as much as possible from the inboard wing filler caps, the wet tip tanks became partially filled because of the wing's dihedral, resulting in a total of 188 gallons of fuel (182 usable) on board. In order to fill the wet tip tanks, about 6 gallons of fuel would be added to each tip tank through the wet tip tank fuel filler cap. Fuel Consumption The accident airplane's EDM indicated that the airplane consumed about 28 gallons of fuel per hour (gph) during the accident flight while at cruise power. According to the airplane's pilot operating handbook (POH), the airplane consumed about 34 gph of fuel at maximum cruise power (200 kts) and about 18 gph at economy cruise power (163 kts). Weight and Balance The airplane's maximum gross weight was 5,500 lbs. Based on passenger weights provided by the medical examiner, the airplane's takeoff weight was calculated as 5,598 lbs with 50 gallons of usable fuel and 5,526 lbs with 38 gallons of usable fuel. The airplane's center of gravity was 86.7 inches at the time of the accident; the acceptable cg range with low fuel was 77.7 to 86.2 inches. Airplane Performance The Beech 58 engine-out procedure in the POH directed flaps to be retracted and the propeller of the inoperative engine to be feathered. The airplane's performance charts indicated a one-engine-inoperative climb capability of about 300 feet per minute (fpm) with the inoperative engine's propeller feathered, flaps up, and a gross weight of 5,300 lbs. A flight operations pilot for the airplane manufacturer who regularly performed single-engine drag demonstrations reported that lowering flaps from 0° to 15° with one engine inoperative resulted in a 150-fpm decrease in climb rate and an unfeathered propeller configuration resulted in a 400-fpm decrease in climb rate. METEOROLOGICAL INFORMATIONThe 1,200 ft agl ceiling reported by the ERV automated weather observation system correlated to a ceiling at the accident site of about 950 ft agl. A pilot who flew an approach to ERV reported 2,400 ft msl cloud bases, which correlated to a ceiling at the accident site of about 550 ft agl. AIRPORT INFORMATIONFuel System The airplane's fuel system comprised three fuel cells and one wet tip tank for each wing. Total fuel capacity for the airplane was 200 gallons; the three fuel cells in each wing held a total of 83 gallons of usable fuel and 3 gallons of unusable fuel, and the wet tip tank held 14 gallons of fuel, all of which was usable. The wing fuel cells and wet tip tanks were interconnected so that all usable fuel was available with the fuel selector valve for each wing in the ON position and supplying fuel to its respective engine. The CROSSFEED position on the fuel selector was only to be used in an emergency. Each wing had two flush-type fuel filler caps: one located in the outboard end of each outboard leading-edge fuel cell and one in the wet tip fuel tank. Fuel quantity was measured by float-type units that electrically transmitted a single indication for each wing system to fuel quantity indicators in the cockpit. The fuel quantity indicator would show full until the respective wing fuel cells contained less than about 75 gallons. According to an American Bonanza Society (ABS) technical representative, the three fuel quantity transmitters in each wing were wired in series with one another. Fuel quantity would be at least 75 gallons at 199 ohms and 3 gallons of unusable fuel at 0 ohms. In this range, the resistance value of the transmitter circuits in each wing was designed to be directly proportional to the amount of fuel. The caution range (yellow band) on the cockpit fuel quantity indicators was from 0 to 1/8th of the amount indicated by the fuel quantity indicator (about 9.33 gallons usable per wing). Fuel level sight gauges on the leading edge of each wing only indicated fuel levels from 40 to 60 gallons per wing. It was not possible to use a dipstick to check fuel quantity due to each wing's dihedral and the location of the filler caps. Fueling Information Fueling of an exemplar 1999 Beech 58 showed that when the airplane's wing fuel cells were filled as much as possible from the inboard wing filler caps, the wet tip tanks became partially filled because of the wing's dihedral, resulting in a total of 188 gallons of fuel (182 usable) on board. In order to fill the wet tip tanks, about 6 gallons of fuel would be added to each tip tank through the wet tip tank fuel filler cap. Fuel Consumption The accident airplane's EDM indicated that the airplane consumed about 28 gallons of fuel per hour (gph) during the accident flight while at cruise power. According to the airplane's pilot operating handbook (POH), the airplane consumed about 34 gph of fuel at maximum cruise power (200 kts) and about 18 gph at economy cruise power (163 kts). Weight and Balance The airplane's maximum gross weight was 5,500 lbs. Based on passenger weights provided by the medical examiner, the airplane's takeoff weight was calculated as 5,598 lbs with 50 gallons of usable fuel and 5,526 lbs with 38 gallons of usable fuel. The airplane's center of gravity was 86.7 inches at the time of the accident; the acceptable cg range with low fuel was 77.7 to 86.2 inches. Airplane Performance The Beech 58 engine-out procedure in the POH directed flaps to be retracted and the propeller of the inoperative engine to be feathered. The airplane's performance charts indicated a one-engine-inoperative climb capability of about 300 feet per minute (fpm) with the inoperative engine's propeller feathered, flaps up, and a gross weight of 5,300 lbs. A flight operations pilot for the airplane manufacturer who regularly performed single-engine drag demonstrations reported that lowering flaps from 0° to 15° with one engine inoperative resulted in a 150-fpm decrease in climb rate and an unfeathered propeller configuration resulted in a 400-fpm decrease in climb rate. WRECKAGE AND IMPACT INFORMATIONThe airplane impacted a rocky ravine about 120 yards from the final radar data point and about 6 miles from the airport. There was no postimpact fire and the airplane came to rest upright on a heading of 246° (see figure 2). The wreckage was contained within the footprint of the airplane, indicating a low forward groundspeed. Elevation at the accident site was 1,868 ft msl and trees about 40 yards northeast were the nearest obstructions. Figure 2. Photograph of an aerial view of the accident site All flight control surfaces were present and flight control cable continuity was established from the tail surfaces to the aft empennage, where the cables were bound by the cabin floor, which was crushed by impact forces. Aileron and aileron trim tab cable continuity was established from the control surface to the wing root. About 1 gallon of fuel was drained from the left-wing fuel cells on the day of the accident. When the left wing was lifted at the wing tip on the day after the accident, about 1 cup of fuel was observed in the left-wing fuel cells and about 1 cup of fuel drained from a breached area near the engine nacelle. No fuel was observed in the right-wing wet tip tank or the right-wing fuel cells. All fuel tank caps were secured. There was no evidence of fuel blight on the area surrounding the airplane. Four of the six fuel cells were in their installed position with no obstructions. The left-wing box cell was loose at the top due to impact damage and the right-wing inboard leading-edge fuel cell was in the installed position, except where cut by recovery personnel. The left fuel selector was near the ON position; it was positioned about 1/4 toward OFF. A small amount of fuel was found in the left fuel selector valve and fuel strainer. The right fuel selector was in the ON position. No fuel was present in the right fuel selector valve or fuel strainer. No water was detected. Postaccident resistance testing of the six fuel quantity transmitters revealed a total transmitter resistance at the empty setting of 13.7 ohms in the left wing and 14.6 ohms in the right wing. Factory specification resistance for each of the six individual transmitters was 0 to 0.5 ohm at the empty setting. According to the ABS technical representative, the additional resistance found in the six transmitters corresponded to a reading of about 5 gallons more than the actual fuel for each wing, (or about 1/16 tank more than the actual amount shown on each fuel quantity indicator), which would equal about 20 to 24 minutes of flying time. Impact damage precluded testing for additional resistance in the fuel quantity circuits. Both fuel quantity gauges and engine fuel flow transducers were tested, with no anomalies noted. Testing reports are in the docket for this investigation. The landing gear were in a retracted position. The left-wing flap actuator position corresponded to a 15° flap setting; the right-wing flap actuator was fractured. Both electric fuel boost pump switches were at the high position. The throttle, propeller, and mixture controls were all near the full-forward position. The propeller for the left engine separated from the engine during the impact sequence. Blades 'A' and 'B' remained attached to the hub. Blade 'A' exhibited leading-edge burnishing and was bent aft at the tip. Blade 'B' exhibited leading-edge gouging, chordwise and spanwise scratching, and was curled forward from the root. Blade 'C' was located under the left-engine cowling and curled aft at the tip with gouging. The propeller for the right engine remained attached to the engine and all three blades remained in the hub. Blade 'A' was straight with minimal damage. blade 'B' was bent aft at the root, and blade 'C' was straight, with light leading-edge gouging along the outer half of the blade. The position of the three blades was not feathered and was in or near the low-pitch stop position. Both engines were examined, and no engine anomalies were observed that would have prevented normal operation. ADDITIONAL INFORMATIONEDM Data A J.P. Instruments EDM-760 was recovered from the wreckage and downloaded. Data from the last 10 flights, including the accident flight, were recorded at 6-second intervals; these data included fuel flow, fuel used, exhaust gas temperatures, cylinder head temperatures, and shock cooling rate of the two engines. After fuel flow to the left engine decreased to 0 gph where it remained for about 40 seconds, fuel flow increased to about 32 gph and remained near 30 gph for the remainder of the recorded data. After fuel flow to the right engine decreased to 0 gph, it remained near 0 until about 4 minutes before the end of the data, when it increased to about 15 gph for a few seconds and then returned to 0. About 3 minutes before the end of the data, the r
The pilot's inadequate preflight fuel planning and fuel management, which resulted in a loss of engine power due to fuel exhaustion. Also causal was the pilot's failure to follow the one-engine inoperative checklist and maintain the airplane's minimum controllable airspeed by properly configuring the airplane, which resulted in a loss of airplane controllability.
Source: NTSB Aviation Accident Database
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