N501CE

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 ...