Posted on July 31, 2024
The design of a new passenger ferry’s engine and inadequate follow-on training for engineering crewmembers led to a 2022 fire aboard a Staten Island ferry, the National Transportation Safety Board (NTSB) said on Tuesday, July 30.
Background of the accident
A fire broke out in the engine room of the passenger ferry Sandy Ground in New York Harbor with 884 persons aboard on December 22, 2022. The crew’s actions to contain and extinguish the fire, combined with a quick response from good Samaritan vessels, resulted in the safe evacuation of all on board. Damage to the vessel totaled US$12.7 million.
As a result of the investigation, the NTSB issued a safety alert and five safety recommendations. The latter included recommended regulatory changes to design requirements for diesel engine fuel oil return systems.
While attempting to manage fuel oil levels as the vessel was transiting between Staten Island and Manhattan, oilers aboard Sandy Ground closed both day tank fuel oil return isolation ball valves, which caused the overpressurization of the fuel oil system.
The fuel oil filters on the main engines ruptured, leading to the spray of fuel oil that ignited a fire. A delay in shutting down the main engines led to fuel oil continuing to spray and increased the severity of the fire.
Design issues identified and recommendations made
Sandy Ground was the second of three Ollis-class ferries built for the City of New York Department of Transportation (NYCDOT) and was put into service six months before the fire.
The Ollis-class ferries were not originally constructed with fuel oil return isolation valves. Instead, isolation valves were added after delivery to regulate the day tank fuel oil levels.
The Ollis-class vessels also did not have a means to relieve the pressure in the fuel oil return lines if both fuel oil return isolation valves were closed, and the relief valves in the fuel oil system did not have independent return lines. The NTSB said these design flaws led to the overpressurisation.
The NTSB recommended the US Coast Guard update marine engineering regulatory requirements to require diesel engine fuel oil return systems on US-flagged vessels be designed to have either unimpeded return flow or a pressure relief valve. Until regulatory requirements can be updated, the NTSB recommends the coast guard develop and disseminate design guidance for new construction diesel engine fuel oil returns systems to have unimpeded flow from the engine or other arrangements to prevent overpressurisation.
The NTSB made a similar recommendation to the American Bureau of Shipping (ABS) to propose the same design requirements to the International Association of Classification Societies (IACS).
The NTSB also found the engineering crewmembers were not adequately trained on the fuel system for the new Ollis-class ferries. The crewmembers did not receive follow-on training after fuel oil return isolation ball valves were installed on Sandy Ground. The new vessels did not have relief valves in their fuel oil return systems like other Staten Island ferries.
The crewmembers likely thought the fuel oil system could not be overpressurised as relief valves prevented overpressurisation on the other ferries. In addition, the engine room crewmembers on board Sandy Ground each had a different understanding of the fuel oil system.
The NTSB is issuing a safety alert to vessel operators about the importance of understanding diesel engine fuel oil system return design and operation to prevent overpressurisation of fuel oil systems.
This is the second fire in two years the NTSB investigated in which overpressurisation of the main engine fuel return system, caused by closed valves, led to diesel fuel spraying and igniting a fire. The other was a 2021 engine room fire on a towing vessel transiting the Mississippi River in Missouri.
Marine Investigation Report 24-17 and Safety Alert 94 are available online.
