Event Description
During cruise flight, smoke infiltrated both the cabin and cockpit, prompting the crew to execute a precautionary landing. Upon landing, the flight attendant, acting on the captain's command, directed an evacuation through the rear exits of the aircraft. During the evacuation, one passenger sustained a broken ankle, classified as a serious injury.
Investigation Findings
Subsequent investigation identified a failed bearing in the left engine as the root cause. The bearing failure allowed a shaft to shift, which in turn led to the destruction of an oil seal. Compromised oil integrity permitted oil to enter the cabin air system, where it was emitted into the cabin and cockpit as smoke. The smoke nuisance and subsequent evacuation were direct consequences of this mechanical failure.