Accident Overview
On June 19, 2018, about 1200 mountain standard time, a Cirrus SR22, registration N764CT, was destroyed in an accident near Aguila, Arizona. The pilot was seriously injured, and the passenger sustained minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Pilot's Account
The pilot reported that approximately halfway through the cross-country flight, the oil temperature exceeded the maximum limit on the gauge, and oil pressure dropped to between 14 and 16 psi. The airplane then began to shudder violently. The pilot initiated a turn toward the nearest airport, about 40 miles away. During the diversion, engine speed increased to over 5,000 rpm before dropping to nearly 0 rpm. The pilot struggled to maintain an altitude of 6,500 ft mean sea level and determined he could not clear a nearby mountain range. While searching for an emergency landing area, the engine completely seized. The cabin filled with smoke, and oil covered the windshield. The pilot deployed the airplane's parachute system, and the aircraft landed approximately 5 seconds later in a ravine. After landing, the airplane was consumed by fire.
Engine Examination
An initial examination revealed that the No. 2 connecting rod had punctured the top aft section of the crankcase. A rusted crankshaft and the remains of the separated No. 2 connecting rod were visible through the hole. The spark plugs exhibited heavy erosion on the electrodes, and the insulators were fractured with significant portions missing. Borescope examination of the cylinders showed signatures consistent with elevated temperatures on the pistons. The No. 5 piston was eroded around its outer circumference, with a hole present and a portion of the top piston ring visible. The exhaust system contained re-solidified melted metal particles, consistent with the postaccident fire.
During engine disassembly, it was found that the Nos. 2 and 5 pistons had experienced a pre-ignition/detonation event that partially eroded the pistons and led to oil starvation of the engine. The cause of the pre-ignition/detonation event could not be determined. Due to the severe fire damage, many engine components, including the magnetos, could not be tested.
Maintenance Records
According to the engine maintenance records, a magneto-to-engine timing check was conducted multiple times, with the most recent check before the accident dated July 27, 2012. An annual inspection was performed on May 9, 2018, at a total time of 1,955.4 hours, with no anomalies noted. However, the required 500-hour inspection of the magnetos was not indicated in the maintenance records since their last comprehensive inspection in 2011. The magnetos had accumulated 1,284.1 hours since that time.