Holly Ridge, NC, USA
N3933H
MOONEY M20J
The pilot and three passengers were departing from a 3,591-ft-long grass runway when the accident occurred. Review of a video recorded by a witness on the ground revealed that, after becoming airborne, the airplane’s wings wobbled as it climbed, turned left, and descended into a wooded area about two-thirds down the runway. Onboard video recorded by a surviving passenger revealed that the engine continued to operate throughout the accident sequence and sounds consistent with a stall warning horn were heard before impact. The amount of fuel onboard the airplane at the time of the accident was not determined. The airplane’s weight and balance at the time of the accident was estimated using the actual weights of the occupants and both full fuel tanks and half-full fuel tanks. With the fuel tanks filled to half capacity, the airplane was about 72 lbs under its maximum allowable gross weight and about 2 inches forward of the aft center of gravity limit. Sound spectrum analysis of the audio portions of each video revealed that the engine was operating at or near its maximum takeoff power setting of 2,700 rpm, and engine sound was smooth and continuous throughout. Examination of the airframe and engine revealed no preimpact mechanical anomalies that would have prevented normal operation. The wing flaps were found retracted; the pilot’s operating handbook for the airplane indicated that flaps should be extended to 15° for takeoff.
HISTORY OF FLIGHTOn October 21, 2021, at 1631 eastern daylight time, a Mooney M20J, N3933H, was substantially damaged when it was involved in an accident at Holly Ridge/Topsail Island Airport (N21), Holly Ridge, North Carolina. The commercial pilot and one passenger were fatally injured, one passenger was seriously injured, and one passenger received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Radar data obtained from the Federal Aviation Administration (FAA) revealed the pilot and the front-seat passenger had completed a 30-minute local flight at 1603. Then, two additional passengers boarded the airplane before departing on the accident flight. Review of a video recorded by a witness at N21 revealed that the airplane started its takeoff roll for the accident flight on the 3,591-ft-long grass runway. After lift-off, the airplane’s wings wobbled as it climbed, turned left, and descended into a wooded area about two-thirds the distance down the runway. A video recorded by a surviving passenger revealed that the engine continued to operate throughout the accident sequence and sounds consistent with a stall warning horn were heard before impact. PERSONNEL INFORMATIONThe recovered pilot’s logbook was identified as “Logbook 3”. The first entry was dated October 23, 2006. The last entry was dated September 17, 2021. Between those dates, the pilot annotated 436 hours of flight experience, all but 2.2 hours of which were in the accident airplane. The pilot completed a flight review on September 17, 2021; that flight was the only flight recorded in the logbook during the 14 months before the accident. AIRCRAFT INFORMATIONReview of maintenance records revealed that the airplane’s most recent annual inspection was completed on February 21, 2021, at 3,248.57 total aircraft hours. The tachometer showed 3,252.42 total aircraft hours at the accident site. The weight and balance condition of the airplane at the time of the accident was estimated with full fuel tanks and at half-full tanks, and the actual weights of the occupants. The estimates showed that, with the fuel tanks filled to half capacity, the airplane’s gross weight was about 2,668 lbs and its center of gravity was about 48 inches. Fueled to capacity, the airplane’s gross weight was about 2,860 lbs and the center of gravity about 48 inches. The airplane’s maximum allowable gross weight was 2,740 lbs, and the aft center of gravity limit was 50.1 inches. The accident airport was not equipped with fuel services, and the airport manager stated that most pilots in the area obtained fuel at nearby Henderson Field (ACZ), Henderson, North Carolina. A request for fueling receipts from ACZ for the accident airplane revealed that the airplane was serviced with 47 gallons of 100LL aviation fuel on September 17, 2021. AIRPORT INFORMATIONReview of maintenance records revealed that the airplane’s most recent annual inspection was completed on February 21, 2021, at 3,248.57 total aircraft hours. The tachometer showed 3,252.42 total aircraft hours at the accident site. The weight and balance condition of the airplane at the time of the accident was estimated with full fuel tanks and at half-full tanks, and the actual weights of the occupants. The estimates showed that, with the fuel tanks filled to half capacity, the airplane’s gross weight was about 2,668 lbs and its center of gravity was about 48 inches. Fueled to capacity, the airplane’s gross weight was about 2,860 lbs and the center of gravity about 48 inches. The airplane’s maximum allowable gross weight was 2,740 lbs, and the aft center of gravity limit was 50.1 inches. The accident airport was not equipped with fuel services, and the airport manager stated that most pilots in the area obtained fuel at nearby Henderson Field (ACZ), Henderson, North Carolina. A request for fueling receipts from ACZ for the accident airplane revealed that the airplane was serviced with 47 gallons of 100LL aviation fuel on September 17, 2021. WRECKAGE AND IMPACT INFORMATIONThe airplane came to rest on a heading of 081°; the empennage rested against a tree in a vertical, nose-down attitude. All major components of the airplane were accounted for at the accident site. The left wing was fractured at the wing root and separated from the fuselage, laying about 12 ft to the right, with the left wing tip and aileron separated from the wing and located about 40 ft east of the main wreckage. The right wing and fuel tank remained attached to the fuselage and contained about 15 gallons of fuel. The left wing fuel tank was breached. Flight control continuity for the left wing was confirmed from the separation point of the wing to the aileron and flap. Continuity of the remaining flight controls was confirmed from the flight control surfaces to the cockpit. Measurement of the flap actuator jackscrew revealed a flap setting of 0°, or fully retracted. The engine was partially disassembled to facilitate examination. The propeller was cut from the engine to allow for engine rotation. The crankshaft was rotated by turning the propeller hub and continuity of the crankshaft to the rear gears and to the valvetrain was observed. Compression and suction were confirmed at all four cylinders using the thumb method. The engine-driven fuel pump was actuated by hand and pumped air from the outlet port. The fuel flow divider was partially disassembled, the rubber diaphragm was undamaged, and fuel was observed in both the pump and the flow divider. The magneto drive was rotated with an electric driver and produced spark at all ignition towers. ADDITIONAL INFORMATIONThe FAA Weight and Balance Handbook, FAA-H-8083-1, stated: Most modern aircraft are so designed that, when all seats are occupied, the baggage compartment is full, and all fuel tanks are full, the aircraft is grossly overloaded. This type of design requires the pilot to give great consideration to the requirements of each specific flight. If maximum range is required, occupants or baggage must be left behind, or if the maximum load must be carried, the range, dictated by the amount of fuel on board, must be reduced. Overloading an aircraft can create a variety of problems: • The aircraft needs a higher takeoff speed, which results in a longer takeoff run. • Both the rate and angle of climb are reduced. • The service ceiling is lowered. • The cruising speed is reduced. • The cruising range is shortened. • Maneuverability is decreased. • A longer landing roll is required because the landing speed is higher. • Excessive loads are imposed on the structure, especially the landing gear. The POH or AFM includes tables or charts that give the pilot an indication of the performance expected for any weight. An important part of careful preflight planning includes a check of these charts to determine if the aircraft is loaded so the proposed flight can be safely made. According to FAA Advisory Circular AC-61-23C, Pilot’s Handbook of Aeronautical Knowledge: The effect of torque increases in direct proportion to engine power, airspeed, and airplane attitude. If the power setting is high, the airspeed slow, and the angle of attack high, the effect of torque is greater. During takeoffs and climbs, when the effect of torque is most pronounced, the pilot must apply sufficient right rudder pressure to counteract the left-turning tendency and maintain a straight takeoff path. According to the airplane’s pilot operating handbook, Section IV, Normal Procedures, Before Takeoff: 14. Wing Flaps – TAKEOFF (15°) TESTS AND RESEARCHAcoustic and vibration analysis of the audio portions of video recorded by a witness on the ground and the passenger in the airplane was performed by both the manufacturer of the airplane’s propeller and an National Transportation Safety Board performance engineer. Their separate and individual findings estimated the engine was running at or about its 2,700 rpm takeoff power setting. The engine sounds were smooth and continuous throughout the entirety of each video.
The pilot’s exceedance of the airplane’s critical angle of attack, which resulted in a stall/mush during takeoff and initial climb. Contributing to the accident was the pilot’s loading the airplane near its maximum allowable gross weight and near its aft cg limit.
Source: NTSB Aviation Accident Database
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