History of Flight
On November 18, 2022, at 1510 central standard time, a Cessna 421C, registration N6797L, was destroyed when it crashed near Decatur, Texas. The pilot sustained fatal injuries. The airplane was operating as a Title 14 Code of Federal Regulations Part 91 positioning flight.
ADS-B data documented two flights that day. The first flight departed Denton Enterprise Airport (DTO) at 1343 and landed at 1430, consisting of rectangular patterns near the airport. The accident flight departed DTO at 1459, proceeding about 30 miles west and climbing to about 2,200 ft mean sea level (msl). Around 1507, the airplane entered a descent and left turn, continuing until the final data point at 1510:19. The airplane came to rest about 125 ft north-northeast of the final data point.
Two witnesses located about half a mile east of the accident site observed the airplane at low altitude in a descent. One witness saw no smoke or fire before the airplane descended below the tree line, followed by a fireball and thin smoke. The other witness observed a slow, descending turn toward the north with steady wings; shortly after losing sight, an explosion occurred. Both engines were on fire when the witness arrived, with fuel leaking from the right engine toward the cockpit.
Aircraft and Maintenance Information
Maintenance records included standard booklet entries ending in December 2018, with separate unsigned copies of annual inspections from February 2020 and March 2021. According to the airplane flight manual, unusable fuel for a Cessna 421 with one wing nacelle locker tank was 7.8 gallons total.
Wreckage and Impact Information
The airplane struck a utility pole and terrain, coming to rest upright about 165 ft from the pole. A postimpact fire ensued, burning vegetation over portions of the site. The left wing separated outboard of the engine and was found near the utility pole with a semi-circular impression consistent with an in-flight impact.
The fuselage showed impact damage. The postimpact fire partially consumed the left wing, both engine nacelles, and a small portion of the cabin. Flight controls remained attached with no preimpact failure or malfunction observed. Flap control continuity was confirmed; the actuator position indicated flaps were retracted at impact. The landing gear was retracted.
The left main fuel tank was partially consumed by fire. The left nacelle fuel tank appeared intact with no visible fuel. No right nacelle fuel tank was installed. The right main fuel tank appeared intact, with about one gallon of fuel drained during recovery. All fuel tank caps were securely installed. The cockpit fuel selectors were both positioned to "RIGHT MAIN". The left fuel selector valve in the nacelle was in the "OFF" position. The right fuel selector was in the "RIGHT" fuel tank position and unobstructed.
Left Engine: The left engine remained in place; mounts were broken. The aft portion showed thermal damage from the postimpact fire. The turbocharger had thermal damage but rotated freely. Teardown revealed no preimpact failure or malfunction.
Right Engine: The right engine remained in place; mounts were broken. Teardown revealed damage consistent with oil starvation throughout the engine. Connecting rods, rod caps, and crankcase bearings showed discoloration and extrusion consistent with overheating and oil starvation. Nos. 1 and 2 crankcase bearings were dislocated. Multiple metallic fragments were distributed throughout the engine. The crankcase interior faces had abrasion damage consistent with fore-aft crankshaft movement. Idler gears were out of position; magnetos provided spark when tested.
Left Propeller: Blades were bent; one blade showed a witness mark from contact with the adjacent actuation pin, consistent with the propeller being at or near the feather pitch stop during impact. Damage indicated low rotational energy at impact.
Right Propeller: Two blades were bent; one undeformed. The piston was near low pitch. A witness mark indicated the propeller was on or near the low pitch stop during impact.
Medical and Pathological Information
The 57-year-old male pilot held a first-class medical certificate with a limitation for near-vision glasses. At his most recent FAA medical examination on May 27, 2022, he reported taking medications for gastric reflux, high blood pressure, high cholesterol, a sleep aid (zolpidem), and seasonal allergies. The autopsy report listed cause of death as blunt force injuries, manner of death accident. The medical examiner noted an enlarged heart (510 grams) with left ventricular thickening and obesity (BMI 39.43). Toxicology testing detected cyclobenzaprine, norcyclobenzaprine, and zolpidem in femoral blood and urine; the generally non-impairing substances amlodipine, atorvastatin, fexofenadine, azacyclonol, and tamsulosin were detected, and albuterol in urine only.
Tests and Research
The fuel flow indicator displayed total fuel used of 119.7 gallons, total fuel remaining 8.3 gallons, left tank fuel used 58.9 gallons, right tank fuel used 60.8 gallons. The device requires proper configuration by the pilot during refueling and does not directly display quantity.
Engine performance data from the onboard monitor showed around 1506 a decrease in right engine speed, fuel flow, manifold pressure, and temperatures consistent with idle power. About three minutes later, an abrupt decrease in all left engine parameters occurred, consistent with complete loss of power. Immediately afterward, right engine parameters increased to takeoff power, but about 30 seconds later, they abruptly decreased consistent with complete loss of power. Data ended shortly after, coinciding with the accident sequence.