WPR24FA010

The pilot’s exceedance of the airplane’s critical angle of attack while attempting to return to the departure airport, which resulted in an aerodynamic stall at an altitude too low for recovery. Contributing to the accident was the failure of the No. 2 connecting rod due to oil starvation for reasons that could not be determined.

During the pilot’s second flight in the experimental amateur-built airplane, he departed on a local, day visual flight rules (VFR) personal flight. A pilot-rated witness reported that, shortly after taking off, the pilot transmitted over the departure airport’s common traffic advisory frequency (CTAF) that the engine had a loss of engine oil pressure and, later, an engine failure. Recorded flight data showed the airplane depart and turn north. Shortly after departure, engine parameters showed a gradual decrease in oil pressure and, by 5 minutes after departure, the oil pressure had decreased to 13 psi. At this point in the flight, the pilot initiated a 180° left turn to the south and began a gradual descent until he briefly leveled off about 1,000 ft above ground level (agl). When the pilot turned back toward the airport, engine manifold pressure and rpm began to decrease and the recorded power output dropped to 49 percent. The airplane continued to descend and the pitch angle gradually increased. About 9 minutes after departure, the No. 2 cylinder exhaust gas temperature (EGT) decreased below the others, indicative of its failure, and the engine speed decreased to 2,300 rpm. The airplane entered a descending 16° right bank before abruptly rolling left to 32°, continuing until the last recorded data point near the site of the wreckage. The witness reported that the airplane appeared to have entered an aerodynamic stall about 100 to 200 ft agl; it then rolled left, descended, and impacted terrain in a left-wing-low, nose-down pitch attitude. Postaccident examination revealed a film of oil on the belly of the airplane that extended from the engine compartment to the tailwheel. The No. 2 cylinder connecting rod had separated from the crankshaft and breached the bottom of the crankcase. The mating surface of the crankshaft journal and the failed connecting rod showed damage consistent with the engine’s operation with insufficient oil. Oil residue was observed in the area around the propeller governor and propeller governor adapter. The propeller governor adapter exhibited multiple hairline fractures however, metallurgical examination of the fracture surfaces revealed they were consistent with overstress. The oil level gage tube was found separated from the crankcase. The oil dipstick was separated from the oil level tube gage. No oil residue was observed in the area surrounding the oil level tube gage. and was undamaged. The reason for the in-flight loss of oil could not be determined. The pilot had an opportunity to conduct an emergency landing at an Air Force base, about 5 nm north of where he made the 180° turn, as well as a dry lakebed about 4 nm to the southwest. Although the pilot was aware of an engine issue, and likely of its impending failure, he did not conduct an emergency landing. During the return to the departure airport, the pilot exceeded the airplane’s critical angle of attack, which resulted in an aerodynamic stall at an altitude too low for recovery.

Documents recovered from the wreckage indicated that the accident pilot had completed RV-8 familiarization training with a flight instructor about three months before the accident. The pilot’s personal logbook of flight experience was not located. According to the pilot’s FAA Airman Certificate and/or Rating Application dated August 31, 2019, the pilot reported 3,889 hours of total flight experience. According to the pilot’s most recent first-class medical certificate application, dated November 17, 2022, the pilot reported 1,000 hours total civil flight experience, and 300 hours in the preceding six months. The experimental amateur-built airplane’s most recent condition inspection was completed by the owner of the airplane, who held a mechanic certificate with airframe and powerplant ratings on June 1, 2023. At the time of the condition inspection, the engine time since major overhaul was 344.6 hours. An autopsy of the pilot was conducted by the Utah Department of Health & Human Services Medical Examiner, Taylorsville, Utah, which listed the cause of death as “blunt force injuries” and the manner of death as “accident.” Toxicology testing performed at the FAA Forensic Sciences Laboratory found no drugs of abuse. On October 10, 2023, about 11:24 mountain daylight time, an experimental amateur-built RV-8, N75RT, was substantially damaged when it was involved in an accident near Centerville, Utah. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to recorded flight data recovered from an on-board Garmin GDU 460, at 11:14:30 the airplane departed runway 17 at Skypark Airport (BTF), Bountiful, Utah, and made a left turn to the north. Shortly after departure, engine parameters showed a gradual decrease in oil pressure began. By 11:19:30, the oil pressure had decreased to 13 psi and the engine speed increased to 3,990 rpm at a manifold pressure of 22.7 inches of mercury. At about 11:19:30, the pilot initiated a 180° left turn to the south, and the departure airport was about 11 miles south. At that time, runway 32 at Hill Air Force Base was about 5 nm to the north, and a dry lakebed was about 4 nm to the southwest. Over the next 5 seconds, manifold pressure decreased to 9.8 inches of mercury, engine speed decreased to 3,030 rpm, and the recorded power output dropped to 49 percent. Between 11:19:45 and 11:22:21, the airplane descended from 5,750 ft mean sea level (msl) to about 4,700 ft msl, where it briefly leveled off, and the airplane's pitch angle gradually increased. At 11:23:48, manifold pressure was 15.7 inches of mercury, engine speed was 2,600 rpm, and 46 percent power. Near that time, the No. 2 cylinder EGT decreased below the others and engine speed decreased to 2,300 rpm. Airspeed was 77 knots indicated when the airplane entered a descending 16° right bank before abruptly rolling left to 32° at 11:23:56, continuing until the last recorded data point at 11:24:00. The initial point of impact was about 770 ft southeast of the last recorded flight data point. The airplane came to rest on level soft dirt about 4 miles north of BTF, at an elevation of 4,208 ft msl. A pilot-rated witness who was monitoring the BTF CTAF reported that the pilot declared an emergency due to low oil pressure over Lagoon Amusement Park, and that he intended to return to the departure airport just over 8 miles north of BTF. A subsequent radio call was heard from the pilot reporting an engine failure northwest of Centerville Interchange located about 6 miles north of the departure airport. The witness reported that the airplane appeared to have stalled about 100 ft - 200 ft agl before it impacted terrain. The airplane impacted terrain in a nose-down, left-wing-low attitude. The first identified point of impact was marked by red navigation light lens fragments and a crater consistent with engine impact. The airplane came to rest about 6 ft east of the first identified point of impact, and the nose of the airplane was oriented on a heading of 020° magnetic. The left wing remained attached to the fuselage and the inboard leading edge was separated from the wing root. Additionally, compression signatures were observed on the inboard trailing edge at the wing root. The right wing’s inboard leading edge was compressed into the fuselage at the wing root. Control continuity was established from the cockpit to the left and right ailerons, the rudder pedals to the rudder horn, and the control stick to the elevator. The left flap torque tube sustained impact damage, and the right flap remained in the retracted position. The lower fuselage exhibited impact damage from the firewall to the empennage, and a coating of oil was present on the belly of the airplane. The two-blade propeller remained attached to the crankshaft, with impact damage observed at the crankshaft flange. One blade was bent aft about 45°, with faint rotational scoring and minimal leading edge damage observed; the other blade was unremarkable. All cylinders and accessories remained attached to the engine. The propeller governor was found mounted to the accessory case with its control arm and cable impact fractured from the unit. Oil residue was observed on the engine around the propeller governor and propeller governor adapter. Numerous hairline fractures were observed throughout the propeller governor adapter with impact damage to the oil fitting. Metallurgical examination of the fracture surfaces found they were consistent with overload. The oil level gage tube was found to be impact damaged and separated from the crankcase. The undamaged oil dipstick was found separated from the oil level gage tube and located about 10 ft from the engine compartment. No damage to the oil level gage tube neck or threads, or oil dipstick threads were observed. No oil residue was observed in the area surrounding the oil level gage tube. The top spark plugs were removed from the cylinders, and each cylinder was examined with a lighted borescope, revealing a failure of the No. 2 piston connecting rod. The No. 2 cylinder was removed, and the connecting rod, cap, and bearings displayed signatures consistent with oil starvation. The oil sump was removed from the crankcase for further examination. During the removal of the oil sump, the attaching hardware was found loose when turned with a wrench by investigators. The oil sump contained fragments of the connecting rod and end cap.