What happened
Approximately seven minutes after takeoff, while the aircraft was climbing, the pilot observed a significant drop in oil pressure. Shortly thereafter, an unusual noise was heard coming from the engine. The pilot attempted to divert the aircraft back toward the airport; however, the engine began running roughly before eventually failing.
During the subsequent emergency landing attempt, the aircraft impacted terrain in a dry river wash and caught fire. The accident resulted in 1 fatality at the scene. The pilot, who sustained thermal injuries, and one passenger both succumbed to their injuries one day after the accident, bringing the total to 3 fatalities.
The investigation
An examination of the aircraft revealed evidence of oil loss and oil exhaustion. Investigators found a heavy coating of oil on the belly of the aircraft. Specifically, evidence indicated that a B-nut fitting, located on an oil line running from the engine to the right oil cooler, had backed off the nipple fitting on the engine.
Further investigation determined that the pilot performed his own oil and oil filter changes, having completed a change just two days prior to the accident. The specific oil supply line involved in the failure is one that is typically removed during oil changes to facilitate the removal of the oil filter and to drain the oil cooler.