History of Flight
On May 6, 2023, at 1522 central daylight time, a Cessna 310D, registration N6798T, was destroyed when it struck cedar trees and terrain about 1/4 mile southwest of runway 16 at Ennis Municipal Airport (F41), Ennis, Texas. The pilot and a pilot-rated front-seat passenger were seriously injured; the rear-seat passenger was fatally injured. The flight was operated as a personal flight under Title 14 Code of Federal Regulations Part 91.
ADS-B data was not available for the accident flight. The pilot-rated front-seat passenger reported that the pilot initiated a go-around while on final approach for runway 16. She stated she was not sure why the go-around was performed. During the go-around, the airplane veered to the right and rolled. The pilot's statement was not obtained due to his injuries.
Personnel Information
According to the pilot's logbook, he passed his private pilot multi-engine check ride on January 12, 2023. He had accumulated 13.9 hours of multi-engine flight time, all in the accident airplane make and model.
Aircraft Information
The airplane was purchased by a family member in June 2021. Logbook records showed the first annual inspection after purchase was in August 2022. The airframe annual inspection was noted by a mechanic as unairworthy, but the engines were found airworthy and signed off. A list of airframe deficiencies was given to the owner. The owner took the airplane to another mechanic, who addressed the deficiencies and approved the airplane for return to service in January 2023.
In February 2020, Continental Aerospace Technologies issued Service Bulletin SB20-01 for IO-470-D engines, requiring removal and cleaning of the fuel plug and screen assembly during every annual inspection. An engine logbook entry from the mechanic who signed off the August 2022 annual inspection indicated all fuel injector components were cleaned and all engine airworthiness directives complied with. However, the mechanic stated their records do not indicate whether SB20-01 was performed.
Before the August 2022 and January 2023 inspections, the airplane had not had an annual inspection since June 2013. Engine logbooks showed both engines were overhauled in November 2001, when all rubber flexible fluid-carrying hoses were replaced. No subsequent replacement of these hoses was recorded.
The airplane was equipped with two Continental IO-470-D engines. Continental recommends hose replacement as needed upon conditional inspection or at engine overhaul, and engine overhaul at 1,500 hours or every 12 years, whichever occurs first, due to possible rubber deterioration.
At the time of the August 2022 and January 2023 annual inspections, the recorded Hobbs time was 1,526.4. Avionics maintenance on May 2, 2023, recorded a Hobbs time of 1,532.7. ADS-B data showed the last recorded flight was April 28, 2023; between January 2023 and the accident, the airplane accumulated about 6 flight hours.
Wreckage and Impact Information
The airplane impacted a lightly wooded area about 1/4 mile southwest of F41. The impact path was on a heading of about 234°, and the airplane came to rest upright about 75 ft from the initial impact site on a heading of about 100°. Debris consistent with the right wing and right engine was found between the initial tree strike and the main wreckage.
The right engine, with propeller attached, was found about 30 ft southwest of the main wreckage. The main wreckage consisted of the fuselage, left and right wings, left engine, left propeller, and empennage. Except for the right wing and empennage, the main wreckage showed burn damage consistent with post-impact fire. All primary and secondary control surfaces except the left aileron (consumed by fire) were intact and attached, with control cable continuity confirmed.
The left propeller had both blades exhibiting chordwise/rotational scoring, bending, twisting, and wave bends on the leading edges. The left propeller was in a low pitch setting and not feathered. The right propeller had chordwise/rotational scoring on one blade, simple bending, no remarkable twisting or leading edge damage, and was also in a low pitch setting and not feathered.
Examination of the left engine revealed soot, debris, and impact damage. Compression and suction were obtained on all cylinders; no preimpact mechanical failures or malfunctions were noted. The right engine showed soot, debris, and impact damage; compression and suction were obtained on all cylinders. During a test cell run, the right engine initially ran roughly. The fuel plug and screen assembly from the fuel injection control housing was removed and found obstructed with black debris, small string-like fibers, and metallic fragments. After replacement with a new exemplar component, the engine started and ran smoothly.
The NTSB Materials Laboratory analyzed the debris and metallic particles from the right engine fuel screen. The black debris was identified as polyurethane; metallic particles consisted of brass and aluminum. Flexible fluid-carrying hoses were made of polyurethane, but post-impact fire damage prevented retaining a sample for comparison. According to Continental Motors, the polyurethane and string-like fibers were consistent with a flexible fluid-carrying hose.
Injuries
The pilot and front-seat passenger sustained serious injuries; the rear-seat passenger was fatally injured.