CEN19FA094

The noninstrument-rated pilot's improper decision to continue flight into convective weather conditions, which resulted in the airplane exceeding its maximum maneuvering speed and the subsequent in-flight breakup. Contributing to the accident was the pilot's inadequate preflight weather planning and his inadequate inflight weather avoidance of that weather.

The non-instrument-rated private pilot and three passengers departed on a cross-country flight in a multi-engine airplane, even though the pilot did not hold multiengine rating. At the time of departure, the weather was reported to be clear. However, a line of thunderstorms and high winds were along the flight route. Radar data showed that the airplane initially flew eastward and that, after entering an area of convective weather, it turned westward, likely to avoid the area of weather. The airplane then flew northeast before resuming eastward flight and entering another area of weather. The airplane then entered a series of descending spiral turns until impact. About 10 hours after the accident, a witness noted wreckage near a roadway, and the airplane was located shortly thereafter. No preimpact anomalies were found with the airframe or engines that would have precluded normal operation of the airplane. All separations were consistent with overload. Parts of the right wing were located between 1 and 3 nautical miles from the main wreckage, indicating that an in-flight breakup of the airplane had occurred. Radar data showed that the airplane was flying at a groundspeed of between 160 and 190 kts before it entered the spiral shaped flight track. According to the manufacturer, the airplane's maximum maneuvering speed was about 135 kts. Thus, the in-flight breakup occurred because the airplane was operating above its maximum maneuvering speed, which exceeded the design load factor of the airplane. Various aviation weather products indicated that the airplane entered areas of significant convective weather twice. Once the airplane entered the clouds and precipitation associated with thunderstorms, the airplane was also in areas that were favorable for icing conditions. No evidence indicated that the pilot received a weather briefing on the day before or the day of the accident. If he had received a weather briefing, he could have been aware of the severe thunderstorms predicted for the flight route. Toxicology testing showed the pilot had taken a beta blocker used in the treatment of hypertension and certain arrhythmias.

According to information from the Federal Aviation Administration (FAA), the 51-year-old pilot held a private pilot certificate with an airplane single-engine land rating. The pilot's last aviation medical examination was on August 8, 2018, during which he applied for an FAA third-class medical certificate. The pilot reported on that medical certificate application that he had accumulated 1,200 hours of total flight time and no hours of flight time in the previous 6 months. He also reported taking dapagliflozin (a medication to treat diabetes), which is not permitted for use by pilots, and was subsequently issued a denial of that medical certificate. The pilot's logbook was found in the wreckage. The entry before the last entry was dated May 7, 2005. The last entry was dated August 23, 2018 and using flight time carried forward on the last page, the pilot's total logged flight time was 250.9 hours. The investigation was not able to determine how much total flight time the pilot had accumulated flying the accident airplane. The airplane had a total standard fuel capacity of 93 gallons (92 gallons useable) distributed between two wing fuel tanks. The airplane also had a total auxiliary fuel capacity of 38 gallons (36 gallons useable) distributed between two inboard wing fuel tanks. The airplane's maximum maneuvering speed was 155 mph (about 134.7 kts). According to the airplane owner's manual, maneuvering speed is the "maximum speed at which abrupt control travel can be used without exceeding the design load factor" of the airplane. The previous owner of the airplane, stated that he sold the airplane to the accident pilot "in the fall" of 2018, but there was no FAA record of the purchase. The previous owner, in part, reported, "The plane performed perfectly. Total airframe time was about 1800 hrs motors were both about 600 hrs. Excellent flying airplane. Good radios and everything worked properly the last time I flew it." In addition, the previous owner stated that the airplane underwent an annual inspection shortly after the accident pilot purchased the airplane. The main wreckage, which consisted of the fragmented fuselage, empennage, inboard wings sections, left outboard wing section, and both engines, was found embedded about 6 to 8 ft below grade in wooded terrain about 62° and 10 nautical miles from GGG. One fuel tank was found fragmented near the main wreckage in the woods and one fuel tank was found in a clearway for an underground pipeline near the main wreckage. Highly fragmented sections of the fuselage, wings, and empennage were found in the woods widely distributed around the main wreckage. A backhoe was used to raise the wreckage from below grade. The rear propeller blades were attached to their hub and that hub remained attached to its propeller flange. However, the flange was separated from its engine crankshaft just forward of its flange. One blade exhibited leading edge nicks and the other blade exhibited S-shaped bending. The front propeller hub remained attached to its engine. However, the hub's blades did not remain attached. One inboard section of a front propeller blade was identified on site, and one outboard section of a front propeller blade was identified on site. Those sections exhibited separations in overload and chordwise abrasion. The outboard section exhibited S-shaped bending. A disassembled instrument gyro exhibited rotational scoring on its rotor and rotor housing. The recovered main accident site wreckage was subsequently taken to a storage facility. An NTSB aerospace engineer and a safety investigator from the airplane manufacturer examined the recovered wreckage at a storage facility in Marshall, Texas, on June 17-18, 2019. The examination revealed that the wreckage from the main site was fragmented and exhibited fore-aft crushing with an accordion style deformation pattern. Three corners of the airplane, the front/fuselage, left wing, and empennage were identified in the wreckage from the main site. The airplane manufacturer defines the location of parts of the airplane longitudinally and laterally using station locations and vertically using waterline locations measured in inches from a datum. The wing station (WS) datum is located at the centerline of the airplane and distances on the left and right sides are measured outboard to the ends of the wings. A right outboard wing section was recovered about 72° and 1 nautical mile from the main wreckage. This outboard wing section was mostly intact from the outboard end rib inboard about 72 inches. Its aileron was mostly intact and attached. The right aileron rod end was attached to the aileron but fractured from its push-pull tube. The right aileron bellcrank control quadrant was not present in the right wing. However, the wing section exhibited damage in the area of the quadrant consistent with the quadrant being torn out. The right rear spar was fractured near WS 159. The right forward spar upper cap was fractured near WS 112 and it exhibited upward deformation at the fracture. The right forward spar lower cap was fractured near WS 150 and no deformation was observed at the fracture. The right forward spar was twisted clockwise as viewed looking outboard. The right spar fractures had angular features and a dull, grainy appearance consistent with overstress separation. A right outboard flap segment was recovered about 59° and 3 nautical miles from the main wreckage. The flap segment was about 50 inches long and it was mostly intact from leading edge to trailing edge. However, it exhibited buckling damage on its upper and lower skins. A right outboard leading-edge segment was recovered about 72° and 1.7 nautical miles from the main wreckage. This section spanned from WS 110 to WS 133. Its landing gear inspection mirror remained intact. A portion of the landing light housing remained attached to the leading edge. However, no lights remained attached. All separations in control cables exhibited a broom-straw appearance consistent with overload. All observed skin and structure separations exhibited an appearance consistent with overload. There was no evidence of corrosion or other pre-existing conditions on any of the primary structure examined. A safety investigator from the engine manufacturer under NTSB supervision also examined the recovered engines at the storage facility. The front engine data plate was not present and was not located during the airplane recovery. However, its configuration was consistent with a Continental TSIO-360-A engine. The rear engine was a TSIO-360-A engine with serial number 184247-8-A. The front engine exhibited several holes in its crankcase exposing the inside of the engine. No pre-impact failures were noted to its crankshaft or connecting rods. The No. 5 and 6 cylinder heads were impact separated and not observed. The No. 5 cylinder barrel had separated from the crankcase and the piston was lodged in the cylinder barrel, still connected to the crankshaft by the connecting rod. All of the remaining cylinder heads exhibited varying amounts of impact damage. The fuel pump, propeller governor, fuel manifold valve, magnetos, induction and exhaust systems were not observed with the engine. The rear engine exhibited several crankcase breaches and no pre-impact failures were noted to its crankshaft or connecting rods. The No. 1 and 2 cylinder heads exhibited impact damage. The top spark plugs from No. 4, 5, and 6 cylinders were removed and exhibited light grey combustion deposits and the electrodes were worn out-normal when compared to the Champion Check a Plug chart. The fuel manifold valve remained partially attached to the engine. The fuel manifold valve was removed and disassembled with no anomalies noted. The fuel pump remained attached to the engine and exhibited impact damage. The fuel pump was removed, and the fuel pump drive was intact. The fuel pump did not turn and the pump was disassembled.