CEN23FA352

The airplane operator reported that the pilot had recently been checked out in the accident airplane and was operating in the airport traffic pattern for runway 18 when the accident occurred. There were no witnesses to the accident and no flight track information associated with the accident airplane was recovered. The airplane impacted the ground and came to rest about 220 ft north and 330 ft east of the departure end of the runway. Impact marks indicated that the airplane was travelling to the north when it impacted the ground. The airplane was destroyed by impact forces and a postimpact fire. Examination of the airplane found no preimpact anomalies of the airframe or flight control system. The propeller damage was consistent with low or no power production from the engine. The engine examination was limited due to the extent of the impact and postimpact fire damage; however, the crankshaft gear that drives all of the other gears within the engine accessory case was found separated from the crankshaft, and the four attaching bolts and locating dowel pin were broken. The dowel pin was found to have broken due to shear overstress from rotational motion of the crankshaft gear on the crankshaft; however, the fracture mechanism of the bolts could not be determined due to secondary flattening of the fracture surface. Had this gear become separated during flight it would have resulted in a complete loss of engine power, which is consistent with the limited propeller damage. No other preimpact engine anomalies were found that would have precluded normal operation of the engine. Impact markings at the accident site suggested that the pilot may have been attempting to return to the runway for a forced landing when the airplane impacted terrain in a nose- and left-wing low attitude, consistent with a loss of airplane control. It is most likely that the crankshaft gear separated which resulted in a loss of power, however, impact and fire damage precluded the determination of the failure mode.

7F3 had two runways: runway 18/36 and runway 13/31. Both runways measured 4,000 ft long. Runways 36 and 31 were connected by an approximate 2,900-ft-long taxiway. On August 7, 2023, about 1535 central daylight time, a Cessna 150, N5610E, was destroyed when it was involved in an accident near the Caddo Mills Municipal Airport (7F3), Caddo Mills, Texas. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The operator of the airplane reported that the pilot had recently conducted two flights in the accident airplane with a flight instructor. The first flight was to perform a check flight for insurance purposes. The operator reported that the first flight was satisfactory, but the pilot could not fly the airplane alone until he received an FAA medical certificate, so the second flight was also flown with the instructor. The pilot received a first-class medical certificate on the day of the accident and came to the airport to fly the accident airplane. The operator reported that he was at the airport and knew the pilot was flying, but his attention was on other tasks. He said that he did notice at least once that the airplane was in the traffic pattern for runway 18 at 7F3. He estimated that the airplane was airborne for about 30 minutes, and he then noticed smoke coming from the opposite end of the airport. He also noticed fire trucks on the airport property. The airplane was discovered near the south end of runway 18. There were no reported witnesses to the accident. The airplane was equipped with an Automatic Dependent Surveillance - Broadcast (ADS-B) system that was mounted on the tail of the airplane and replaced the rear navigation light. No flight data related to the accident airplane on the accident date was found. The Southwestern Institute of Forensic Sciences, Dallas, Texas, performed the pilot’s autopsy. According to the autopsy report, the pilot’s cause of death was blunt force injuries of the head and trunk sustained in an aircraft crash, and thermal injuries contributed to the cause of death. Toxicology testing performed by the FAA Forensic Sciences Laboratory on the pilot’s blood and urine did not identify any substances that are generally considered impairing. The pilot held an FAA private pilot certificate based on his Brazilian pilot certificate, with ratings for airplane single- and multi-engine land. The FAA pilot certificate was issued on January 12, 2023. Review of his pilot flight records revealed 216.7 total hours of flight experience. He had 2.8 hours of flight experience in Cessna 150 airplanes, all of which was in the accident airplane. His first flight in the accident airplane was on March 8, 2023, for 1.2 hours and the second flight was on June 8, 2023, for 1.6 hours. The airplane came to rest upright on airport property about 200 ft north and 330 ft east of the departure end of runway 18. The airplane was about 40 ft north of the edge of the taxiwayconnecting the departure ends of runways 18 and 13. An impact mark was found in the turf at the south edge of the taxiway that was consistent with nose wheel impact, and the nose wheel and fractured nose wheel fork were found near this impact mark. There was another impact mark on the pavement adjacent to the nose wheel impact that was consistent with the airplane’s fuselage. The relative position of these marks was consistent with a nose- low impact attitude. A third impact mark on the pavement west of the other two marks was consistent with the left wingtip. The left wingtip was bent upward at the leading edge, consistent with a left-wing low impact. There were linear abrasion marks in the pavement leading from the three impact markings across the pavement to the wreckage. There was burned vegetation around the wreckage and along the edge of the taxiway. The airplane was examined at the accident site and the flight control cables were continuous from the respective cockpit controls to the control surfaces except for the aileron balance cable, which contained one break consistent with overload failure. The manual flap handle was in the flaps-up position. Both wings were mostly intact with ailerons and flaps still attached. There was burning and melting of both wing roots due to the postimpact fire. The aft fuselage and empennage were intact with the rudder and elevator still attached. The postimpact fire consumed the cabin section of the fuselage above the floor. The airplane’s 2-blade metal propeller had one blade that was straight with little damage. The other blade was bent rearward with some chordwise scratching. The propeller damage was consistent with low or no power being produced by the engine. The engine accessory case had almost completely melted due to the postimpact fire. The magnetos were partially melted, precluding functional testing. The upper spark plugs were removed with no discrepancies noted. The propeller could only be partially rotated by hand due to the position of the airplane at the accident scene. The rotation was enough to determine movement of all the pistons within their cylinders, confirming continuity of the crankshaft. During the partial rotation, it was noted that the rear crankshaft gear, that drives all of the other gears within the accessory case, was not rotating. The four attaching bolts and the dowel pin that interfaced the gear to the crankshaft were broken. The gear, with one half of the dowel in it, and the four bolts were retained for metallurgical evaluation. Laboratory examination of the crankshaft gear and attaching bolts revealed that the lock-wire was still intact. Three bolts were broken at the third thread from the straight portion of the shank and the fourth bolt was broken at the 2nd thread. The fracture mechanism for the bolts could not be determined due to secondary flattening of the fracture surfaces. The fracture surface of the locating dowel pin within the gear revealed signaturesconsistent with shear overstress. The direction of the shear was consistent with fracture from rotational movement of the gear on the crankshaft.