BEECH A36 — Topock, AZ

What happened

The pilot departed on a visual flight rules, cross-country flight. ADS-B data indicated that the airplane departed the runway and made a climbing turn. During the climb, the pilot contacted air traffic control for flight following, and shortly after reported that the engine was losing oil pressure and that he was returning to the departure airport. ADS-B data showed that the airplane made a 180° turn and the airplane’s altitude began to decrease.

During the return, the airplane’s altitude and ground speed continued to decrease. The pilot informed the controller that he had configured the airplane’s engine power to idle. Shortly after, radio contact with the accident airplane was lost, but the controller asked the pilot of another aircraft operating in the area to assist. The pilot of the assisting aircraft transmitted a radio call to the controller that the accident airplane’s “engine is burning up.” The pilot of the assisting aircraft attempted to visually identify the distressed airplane, and moments later spotted heavy smoke emanating from wreckage.

Postaccident examination of the engine revealed a hole in the top of the crankcase above the No. 4 cylinder, and the No. 4 connecting rod and piston pin had exited the crankcase. Disassembly of the engine revealed oil starvation near the rod cap area of the I-beam. The main bearings showed normal operational signatures and the crankcase and crankshaft oil passages were unobstructed and free of foreign objects or debris. The bearing end of the I-beam showed thermal discoloration that appeared white/light grey in color, with dark grey progression emanating from the trapezoidal contour into the I-beam and flanges. The No. 4 piston connecting rod cap and connecting rod bearings were fracture separated and remnants of each were found in the oil sump. One of the connecting rod cap bolts was found lodged between the camshaft and the crankcase. The associated connecting rod cap nut and the opposite side bolt and nut were not readily identifiable; however, metallic debris consistent with the bolt and nut were found in the oil sump. Since the No. 4 connecting rod received its lubrication from the unobstructed main bearing oil passage, it is likely that the oil starvation event occurred between the main bearing and the No. 4 connecting rod bearings and the connecting rod cap.

Although there were potential off-airport emergency landing locations about 4 nautical miles (nm) to the north and to the south of the accident location, the pilot chose to attempt to return to the accident airport. While the pilot managed the inflight engine failure and inflight fire, the airplane’s altitude was not sufficient to return to the airport, resulting in an off-airport emergency landing, and the airplane impacted rough desert terrain.

The pilot’s autopsy revealed that he had coronary artery disease and aortic plaque. His toxicology was positive for midazolam, ketamine, and norketamine. The pilot’s coronary artery disease and aortic plaque were associated with some increased risk of an impairing or incapacitating cardiovascular event. However, there was no indication that such an impairing event occurred before the crash. There is a high probability that both midazolam and ketamine were administered during the pilot’s post-crash treatment.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.