The National Transportation Safety Board (NTSB) reported that a crack in the propeller blade of a Matson container ship caused a loss of hydraulic oil and propulsion while sailing in the Pacific Ocean on August 11, 2022. The incident resulted in the loss of up to 1,632 gallons of hydraulic oil and approximately $3 million in damage. Investigators determined that the cracked blade on the vessel’s variable pitch propeller system did not meet the manufacturer’s design specifications, leading to the failure.
The US flag Mountain, a 681-foot container ship owned by Matson Navigation Company, Inc., was en route from Anchorage, Alaska, to Portland, Oregon, for drydock repairs when the crew shut down the main engine due to propeller system problems, causing a loss of propulsion near Portland. During dry docking, a third-party contractor discovered cracks and breaks in the No. 4 blade of the 5-blade propeller, with discrepancies in engineering, material, and chemical composition compared to the manufacturer’s specifications.
NTSB investigators determined that the crack and break in blade No. 4 were likely an isolated incident due to non-compliance with specifications. The blade manufacturer made revisions to improve fatigue fracture resistance, including adjusting inside radius requirements and adding more bolt holes to counterbores. A manufacturer analysis of similar propeller systems on other ships did not reveal further cracks, suggesting the issue was specific to the non-compliant blade on the Matson container ship.
