Oroville, CA, USA
N7641R
BEECH 19A
The accident pilot was a partial owner of the accident airplane, which had not flown for several months until he attempted to fly the airplane about 2 weeks before the accident. During this previous flight the pilot and his student were forced to abort two takeoff attempts after the airplane failed to climb. The pilot and pilot-rated passenger, who was also a flight instructor, had planned to fly the airplane on the day of the accident to troubleshoot the performance deficiency. During takeoff on the accident flight, the airplane reached an intermediate altitude before it started to settle momentarily. The airplane then continued to climb to a peak altitude of about 100 ft above ground level and then it started a right turn that progressively became steeper. Subsequently, the airplane impacted the ground in a nose-down attitude. An analysis of the engine harmonics during takeoff suggested that the engine may have encountered anomalies when the airplane began its right turn, but this could not be substantiated as postaccident examination of the airframe and engine did not reveal any preimpact mechanical anomalies. The fuel selector was found between the RIGHT tank detent and the OFF position at the accident site. During the flight 2 weeks earlier the accident the pilot had placed the handle in a similar position before takeoff. As there were no preimpact mechanical anomalies with the engine, it is likely that the improper placement of the fuel selector in the OFF position during takeoff resulted in fuel starvation and a partial loss of engine power. Performance computations indicated that the airplane was capable of a successful takeoff as it was below its maximum gross weight. The airplane’s center of gravity (CG) was nose-heavy, which likely would have resulted in difficulty in lifting the nose during takeoff and during reduced power situations. However, this CG condition is only likely to have affected takeoff and likely did not contribute to the accident. Recorded data suggests the airplane entered an accelerated stall in the turn when it exceeded the critical angle of attack without maintaining adequate airspeed. The investigation was unable to determine if the pilot-rated passenger was aware of the airplane’s takeoff issues 2 weeks before the accident. It is also unclear who was piloting the airplane in its final moments; however, the pilot was likely flying at the time considering he was a part owner in the airplane and given his motivation to troubleshoot the performance deficiency. While cardiovascular conditions placed the pilot at an increased risk for a sudden cardiac event, operational evidence does not suggest that this occurred and was likely not a factor in this accident.
HISTORY OF FLIGHTOn June 2, 2022, about 1218 Pacific daylight time, a Beech 19A Musketeer airplane, N7641R, was substantially damaged when it was involved in an accident near Oroville Municipal Airport (OVE), Oroville, California. The pilot and pilot-rated passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to a video of the accident flight captured by a witness, who was also a student of the accident pilot, the pilot and passenger completed an engine run-up and subsequently taxied to runway 13 where they began a ground run. Data retrieved from an onboard recorder showed that the airplane started the ground run about 1218:00. The engine sounded smooth and continuous in the video as the airplane lifted off the runway in about 1,300 ft and transitioned into a climb. About 15 seconds later the airplane began to descend. The airplane started another climb about 4 seconds later, which was immediately followed by a right turn. The data recorder showed that the airplane reached a peak altitude of about 282 ft mean sea level (msl) (about 107 ft above ground level) at 1218:39 before it started to descend. The airplane’s rate of turn began to increase during the turn, at which time the video ceased. The final data point from the recorder was taken at 1218:43 and captured the airplane at an altitude of 272 ft msl and a groundspeed of 53 kts. The witness reported that the airplane impacted the ground seconds after he terminated the video to assist the occupants of the airplane. The witness reported that he flew the accident airplane with the pilot about 2 weeks before the accident. After an uneventful preflight inspection and engine run-up they taxied to runway 31 where they began a ground run. They performed two attempted takeoffs and aborted both after the airplane failed to climb. According to the witness, the pilot and pilot-rated passenger had planned to fly the airplane on the day of the accident to troubleshoot the performance deficiency. Photograph 1: Accident site from the southeast PERSONNEL INFORMATIONAccording to the pilot-rated passenger’s flight logbook entries for the previous 12 months, he had accumulated most of his flight time that year in mostly Cessna 172 and 182 model airplanes. A recent flight record was not recovered for the accident pilot, but a flight logbook from 2011 to 2014 showed that most of his experience during this time frame was in Cessna 172 model airplanes. The witness reported that the accident pilot owned and operated a variety of different Cessna 172 airplanes in his flight history. According to the witness, who was also a student of the pilot’s, on the morning of the accident he communicated his concerns about the airplane “not wanting to fly.” The pilot responded that “the airplane wants to fly” and when the witness pushed the issue further, the pilot said, “the airplane wants to climb…this airplane was born to fly.” The witness further reported that he had always felt that the pilot was safety minded before the accident. AIRCRAFT INFORMATIONAccording to the witness, about 2 weeks before the accident, the pilot decided to fly the airplane after it had sat undisturbed in its hangar for some time. The airplane’s operating records indicated that it was last flown about 6 months before. They filled the tanks with 20 gallons of fuel in each tank and then completed a preflight inspection and an engine run-up before they began their takeoff roll on runway 31. The witness was flying the airplane from the left seat at the time. After the airplane lifted off the runway and reached about 40 ft above ground level in a climb, the airplane “stopped climbing, but didn’t appear to lose any rpms.” The pilot took control of the airplane, decreased engine power and landed the airplane on the remaining portion of runway 31. They made a subsequent takeoff attempt with the same result. The witness stated that the pilot then called the pilot-rated passenger, an experienced flight instructor, to help him “figure out what was happening with it.” Fuel System The fuel system is comprised of a fuel tank located in each wing’s leading edge, each with a capacity of 29.9 gallons (including unusable fuel, which is 0.5 gallons per side). Fuel is fed from the selected fuel tank through a fuel selector valve, a fuel strainer, and the electric fuel boost pump before it reaches the engine-driven fuel pump and then the carburetor. According to the system description in the pilot’s operating handbook, “The fuel selector valve handle is located on the floorboards between the pilot and copilots seats. Takeoffs and landings should be made using the tank that is more nearly full. If the engine stops because of insufficient fuel, refer to the EMERGENCY PROCEDURES Section for the Air Start procedures.” The accident airplane was equipped with the fuel selector stop on the selector valve guard as required by Federal Aviation Administration (FAA) Airworthiness Directive (AD) 85-05-02. An entry in the aircraft maintenance logbook from November 6, 2021, showed that the fuel selector was inspected in accordance with AD 75-01-04, which requires the owner to replace the selector valve guard and inspect the valve for binding and to ensure complete shutoff. Cessna vs. Beech Musketeer Fuel Selectors The Beech Musketeer fuel selector handle is equipped with a pointer and a handle end. To select the desired tank, the operator is required to rotate the handle until the pointer faces the desired fuel tank. This position would place the handle end opposite the desired fuel tank (see Figure 1). Figure 1: Beech Musketeer Exemplar Fuel Selector In the accident airplane the rounded portion of the fuel selector handle, as indicated in Figure 1, would need to be placed over the selected fuel tank. Figure 2: Cessna 182 Fuel Selector The fuel selectors in Cessna 172 and 182 model airplanes, which the pilot was familiar with flying, require the operator to place the handle over the desired tank. For example, to select the left fuel tank, the pilot would place the handle over this placarded position (see Figure 1). The witness reported that during their previous flight 2 weeks before when he was receiving instruction, he observed the pilot place the handle end of the fuel selector over the L TANK position , as in the Cessna and not in the accident airplane. . AIRPORT INFORMATIONAccording to the witness, about 2 weeks before the accident, the pilot decided to fly the airplane after it had sat undisturbed in its hangar for some time. The airplane’s operating records indicated that it was last flown about 6 months before. They filled the tanks with 20 gallons of fuel in each tank and then completed a preflight inspection and an engine run-up before they began their takeoff roll on runway 31. The witness was flying the airplane from the left seat at the time. After the airplane lifted off the runway and reached about 40 ft above ground level in a climb, the airplane “stopped climbing, but didn’t appear to lose any rpms.” The pilot took control of the airplane, decreased engine power and landed the airplane on the remaining portion of runway 31. They made a subsequent takeoff attempt with the same result. The witness stated that the pilot then called the pilot-rated passenger, an experienced flight instructor, to help him “figure out what was happening with it.” Fuel System The fuel system is comprised of a fuel tank located in each wing’s leading edge, each with a capacity of 29.9 gallons (including unusable fuel, which is 0.5 gallons per side). Fuel is fed from the selected fuel tank through a fuel selector valve, a fuel strainer, and the electric fuel boost pump before it reaches the engine-driven fuel pump and then the carburetor. According to the system description in the pilot’s operating handbook, “The fuel selector valve handle is located on the floorboards between the pilot and copilots seats. Takeoffs and landings should be made using the tank that is more nearly full. If the engine stops because of insufficient fuel, refer to the EMERGENCY PROCEDURES Section for the Air Start procedures.” The accident airplane was equipped with the fuel selector stop on the selector valve guard as required by Federal Aviation Administration (FAA) Airworthiness Directive (AD) 85-05-02. An entry in the aircraft maintenance logbook from November 6, 2021, showed that the fuel selector was inspected in accordance with AD 75-01-04, which requires the owner to replace the selector valve guard and inspect the valve for binding and to ensure complete shutoff. Cessna vs. Beech Musketeer Fuel Selectors The Beech Musketeer fuel selector handle is equipped with a pointer and a handle end. To select the desired tank, the operator is required to rotate the handle until the pointer faces the desired fuel tank. This position would place the handle end opposite the desired fuel tank (see Figure 1). Figure 1: Beech Musketeer Exemplar Fuel Selector In the accident airplane the rounded portion of the fuel selector handle, as indicated in Figure 1, would need to be placed over the selected fuel tank. Figure 2: Cessna 182 Fuel Selector The fuel selectors in Cessna 172 and 182 model airplanes, which the pilot was familiar with flying, require the operator to place the handle over the desired tank. For example, to select the left fuel tank, the pilot would place the handle over this placarded position (see Figure 1). The witness reported that during their previous flight 2 weeks before when he was receiving instruction, he observed the pilot place the handle end of the fuel selector over the L TANK position , as in the Cessna and not in the accident airplane. . WRECKAGE AND IMPACT INFORMATIONThe airplane came to rest in an approximately 40° nose-down attitude on a heading of about 097° magnetic, about 500 ft south of the departure end of runway 13. All major structures were accounted for at the accident site. The left wing remained attached to the fuselage, and the right wing was partially separated at the wing root. The fuselage frame was deformed about midspan and the tail was canted slightly left of the fuselage. Both the stabilator and rudder remained connected to the empennage at their attachments. The engine remained attached to the engine firewall, which was wrapped around the engine accessory case. Both propeller blades remained attached to the propeller hub, which was still connected to the engine crankshaft. The fuel selector was found between the RIGHT tank detent and the OFF position at the accident site; however, the fuel selector was deformed and exhibited upward bending at its aft end. In addition, the selector’s left silver handle alignment bracket displayed upward bending at the aft end. Disassembly of the fuel selector revealed metallic particles along the circumference of the LEFT, RIGHT, and ENGINE ports. While the selector exhibited some slight resistance, none of the ports were obstructed. Postaccident wreckage examination did not reveal any preimpact mechanical anomalies that could have precluded normal operation. Flight control continuity of the right and left aileron, rudder, and stabilator were traced from their control surfaces to the cockpit controls. Both wing flaps were in the retracted position. Fuel was observed in the left tank at the accident site and a trace amount of fuel was observed in the right fuel tank, which was intact, but the fuel line was fractured at the wing root and an odor consistent with 100 low lead aviation grade gasoline was observed beneath its corresponding wing. Mechanical continuity was established throughout the rotating group, valvetrain and accessory section as the crankshaft was manually rotated at the accessory case with a hand tool. Thumb compression was obtained in proper firing order at all four cylinders and the valves displayed normal lift when the crankshaft was rotated. Examination of the cylinders’ combustion chamber interior components using a lighted borescope revealed normal piston face and valve signatures, and no indications of catastrophic engine failure, detonation, or foreign object ingestion. ADDITIONAL INFORMATIONThe pilot’s operating handbook (POH) included the airplane’s stall speeds in a power OFF configuration at a weight of 2,200 lbs. According to the POH, the stall speed in a flaps up configuration at a level attitude is 58 kts, 30° bank angle is 63 kts, 45° bank angle is 70 kts, and 60° bank angle is 86 kts. The section also includes a note: “maximum altitude loss during a normal stall recovery is approximately 300 ft.” Weight and Balance An airplane weight and balance was computed using the only basic empty weight found within the maintenance records, pilot and passenger weights of 220 lbs each, an estimated baggage weight of 10 lbs, and a fuel weight of 240 lbs (40 gallons). The airplane total weight was approximately 2,180 lbs and the moment was 2,361 in-lbs. According to the POH, the moment minimum and maximum for a weight class of 2,200 lbs was 2,463 in-lbs and 2,603 in-lbs, respectively. The airplane’s forward center of gravity (CG) limit was 112 inches aft from the datum and the aft CG limit was 118.3 inches from the datum. The aircraft CG at the time of the accident was calculated as 108.32 inches from the datum. Performance The airplane’s takeoff distance was computed from the takeoff chart in the POH. The chart assumes a power setting of FULL THROTTLE, mixture leaned to maximum rpm then enriched slightly, flaps UP, a weight of 2,200 lbs on a runway that is a level, dry, and hard surface. Factoring in the approximate wind component of 17-kt gusts and the 88° outside air temperature at the time, the airplane would have required about 1,000 ft of runway to complete the takeoff. Accelerated Stalls The following is an excerpt from the FAA-H-8083-3C Airplane Flying Handbook, which describes accelerated stalls. “At the same gross weight, airplane configuration, CG location, power setting, and environmental conditions, a given airplane consistently stalls at the same indicated airspeed provided the airplane is at +1G (i.e., steady-state unaccelerated flight). However, the airplane can also stall at a higher indicated airspeed when the airplane is subject to an acceleration greater than +1G, such as when turning, pulling up, or other abrupt changes in flightpath. Stalls encountered any time the G-load exceeds +1G are called “accelerated maneuver stalls.” The accelerated stall would most frequently occur inadvertently during improperly executed turns, stall and spin recoveries, pullouts from steep dives, or when overshooting a base to final turn. An accelerated stall is typically demonstrated during steep turns. An airplane typically stalls during a level, coordinated turn similar to the way it does in wings-level flight, except that the stall buffet can be sharper. If the turn is coordinated at the time of the stall, the airplane’s nose pitches away from the pilot just as it does in a wings-level stall since both wings will tend to stall nearly simultaneously. If the airplane is not properly coordinated at the time of stall, the stall behavior may include a change in bank angle until the AOA has been reduced. It is important to take recovery action at the first indication of a stall (if impending stall training/checking) or immediately after the stall has fully developed (if full stall training/checking) by applying forward elevator pressure as required to reduce the AOA and to eliminate the stall warning, level the wings using ailerons, coordinate with rudder, and adjust power as necessary. Stalls that result from abrupt maneuvers tend to be more aggressive than unaccelerated +1G stalls. Because they occur at higher-than-normal airspeeds or may occur at lower-than-anticipated pitch attitudes, they can surprise an inexperienced pilot. Since an accelerated stall may put the airplane in an unexpected attitude. Failure to execute an immediate recovery may result in a spin or other departure from controlled flight.” Center of Gravity According to Chapter 10 of FAA-H-8083-25B, the Pilot’s H
The pilot’s failure to maintain proper airspeed during a turn and his exceedance of the airplane’s critical angle of attack, which resulted in an accelerated stall. Contributing to the accident was the improper placement of the fuel selector, which resulted in fuel starvation and a partial loss of engine power.
Source: NTSB Aviation Accident Database
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