What happened
On the morning of the accident, a Forest Service operated Douglas C-47, registration N148Z, departed from Grangeville, Idaho. The mission involved transporting gear and personnel to the Moose Creek Ranger Station via the Selway River. The flight carried 12 people, including the crew, along with two dogs and 3,100 pounds of cargo. Due to a smokejumper configuration, passengers were seated on the port side facing the cargo.
Approximately 20 minutes into the flight, the aircraft's left engine failed. This failure was likely caused by low oil pressure and overheating components within the nose case. Following the loss of power in the left engine, the propeller was feathered. Shortly thereafter, a catastrophic event occurred on the right engine, where cylinder number eight experienced a failure that led to an intense fire. Within seconds of the initial engine failure, the right engine detached from the wing.
Following the separation of the right engine, the aircraft entered a powerless glide through a narrow canyon for roughly 3.5 miles. The crew attempted an emergency landing on the river, but the aircraft struck a tree and crashed into the water. The impact caused the airframe to break apart. Of the passengers on board, four fatalities occurred, as three survivors were initially rescued but one died from injuries before reaching medical care.
Findings
- The initial engine failure was attributed to rising temperatures in the lubricating oil and nose case components, leading to a loss of oil pressure.
- The separation of the right engine from the wing occurred after a cylinder failure caused an immediate fire.