Incident Overview
The pilot reported that they departed Opa Locka Airport, Opa Locka, Florida, at about 1040. They flew to a practice area west of Opa Locka West Airport to perform basic instrument work, with the right front seat passenger acting as safety pilot. While returning to Opa Locka Airport at an altitude of 1,500 feet, the engine ceased operating abruptly. Attempts to restart the engine were unsuccessful, and the airplane was ditched in the Everglades approximately 2 miles west of Opa Locka West Airport. Prior to the forced landing, the pilot made contact with a controller at the FAA Opa Locka Airport Control Tower. The occupants were rescued by a Miami-Dade County Police Department helicopter and transported back to Opa Locka Airport.
Post-Accident Engine Examination
After the airplane was recovered from the Everglades, a post-accident examination of the engine showed that the engine rotated when the propeller was turned, but the accessory section did not rotate. Disassembly revealed that the crankshaft had fractured in the aft cheek of the No. 2 main bearing. The remains of the main bearing were found in the bottom of the crankcase. Metallurgical examination of the forward end of the crankshaft showed the fracture located in the aft cheek of the No. 2 main bearing journal. The fracture surface exhibited features typical of fatigue progression from the radius of the journal, with multiple origins along a plane approximately 45 degrees to the journal surface. The mating fracture surface was completely damaged by rubbing. The fatigue initiation site at the radius surface did not contain scoring marks or scratches, but circumferential skidding marks and rub damage intersecting the origin area were observed elsewhere in the radius. Skidding and rub damage were also present on the journal surface, which was heat-tinted and rougher than other main bearing journal surfaces.
Bearing and Crankcase Findings
Examination of the No. 2 main bearing pieces indicated they appeared to form one complete set. Sections of the bearings were rounded and displayed a copper-colored region near the edge, corresponding to the middle layer of the tri-metal bearings. The bearing contour matched the crankshaft radius. One bearing piece had its anti-rotation tab fractured off due to overstress. Examination of the crankcase halves showed severe rotational rub damage on the No. 2 main bearing bosses, consistent with rotation of the bearing against the boss. Minor fretting and wear damage was observed on the boss mating surface of main bearing No. 3. Cylinder mounting surfaces near the through-bolt locations at the No. 2 main bearing did not reveal significant fretting or corrosion damage; only minor localized areas were present.
Engine Maintenance History
Logbook records indicated that the engine last received a major overhaul on April 1, 1997, approximately 865.5 flight hours before the accident. On November 25, 1998, about 557.5 flight hours before the accident, all six cylinders were replaced with new cylinders. On August 23, 2001, roughly 298 flight hours before the accident, all six cylinders were replaced with overhauled cylinders. The engine most recently received a 100-hour inspection on March 8, 2003, about 31.8 flight hours before the accident.