Accident Overview
On March 7, 2023, at approximately 1722 eastern standard time, a Cessna 172, registration N64535, was substantially damaged when it was involved in an accident near Miami, Florida. The aircraft was being operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The flight instructor and private pilot were not injured.
According to the flight instructor, about 30 to 40 minutes into the flight, the engine began to produce a “knocking” noise followed by a total loss of oil pressure. The engine then stopped producing power and the propeller “locked up.” The instructor reported that they were unable to return to the airport and executed a forced landing in the Everglades National Park. During the landing, the nose wheel dug into the soft, wet terrain, causing the airplane to slowly flip over. The accident resulted in substantial damage to an engine mount.
The airplane was recovered from the Everglades approximately seven days after the accident and transported to a secure facility for examination.
Engine and Oil System Examination
Examination of the aircraft revealed no major oil streaks on the lower engine cowling and fuselage. However, some dark oily residue was noted on the right underbelly of the airplane, which appeared to have been present for an extended period.
The engine was not seized, and the crankshaft rotated freely when the propeller was manually rotated. During manual rotation, valvetrain continuity and thumb compression were observed on each cylinder. Examination of the engine’s oil system revealed no obvious mechanical failures, but damage consistent with high heat and friction due to a lack of lubrication was observed.
The flight instructor stated that six quarts of oil were on the airplane before departure. However, only about one quart of dark-colored oil was drained from the oil sump after the accident. The oil suction screen was removed and contained several pieces of metallic debris. The oil filter was also removed and was filled with dark-colored oil; the element contained small flecks of carbon. The oil pump was removed, and all gearing was intact. When the accessory gear box was removed, the oil sump was partially exposed, and several large pieces of metal debris were observed. The oil filter tube was found slightly loose but was secured by safety wire. Some oil was observed on the engine case around and below the connection point of the tube.
Maintenance Records
Review of the engine maintenance records showed that the last 100-hour inspection was completed on December 20, 2022, at an engine total time of 1,124 hours. At the time of the accident, the engine had accrued 1,279 total hours, which was 55 hours past the next required 100-hour inspection.