Incident Overview
The aircraft experienced a catastrophic engine failure while descending toward the destination airport, prompting an emergency landing. The pilot reported that the flight was uneventful until preparations began for descent over Lake Mead. Suddenly, a loud 'pop or clunk' emanated from the engine compartment. The engine began to vibrate and run roughly before quitting altogether, accompanied by a large amount of smoke.
Emergency Landing
The pilot selected a paved model airplane field for the forced landing. The landing was successful, but the aircraft could not be stopped before colliding with a berm at the edge of the field. The impact collapsed the landing gear.
Post-Accident Examination
Following recovery, an FAA airworthiness inspector examined the engine. A large hole was discovered in the upper left rear engine case, in the area of the No. 1 and No. 2 connecting rods. The No. 2 connecting rod had separated from the crankshaft, with the journal end severely peened and damaged, protruding from the hole in the case. The No. 2 bearing insert was destroyed, and heat discoloration was noted on the journal saddle. The corresponding portion of the crankshaft also showed heat discoloration and scoring. Additionally, the oil pressure line from the engine to the Hobbs meter pressure switch was found broken at the switch's fitting, with oil covering the engine compartment area around the broken fitting.