NTSB investigation: Engine room fire on board tug Desperado

The National Transportation Safety Board (NTSB) has released an investigation report into an incident in which on February 17, 2023, while the Desperado was transiting Lake Salvador on the Intracoastal Waterway in Bayou Perot, Louisiana, a fire broke out in the engine room that the crew was unable to extinguish, prompting the vessel to be evacuated.

The incident

TThe three crew members on board were unable to extinguish the fire with portable fire extinguishers. They provided ventilation and fuel in the engine room and then evacuated to a ship belonging to the aid organization Good Samaritan. By the time a fireboat arrived, the fire had been extinguished. No pollution or injuries were reported. The total damage to the ship was $30,000.

After a fire alarm was triggered in the wheelhouse and the captain noticed smoke, he immediately switched off the main propulsion engines, causing the
Hydraulic pumps that were mechanically driven by them, preventing the spraying hydraulic oil from reaching the engines and fanning the fire. Then
instructed deckhands to secure ventilation and emergency fuel shut-off valves – preventing further air and diesel fuel from entering the engine room. Upon inspecting the damage after the fire, the crew found that the damage was confined to the port main propulsion engine area, and according to the captain, “except for the one (port) engine that was burned, everything else was fairly normal.” Therefore, the crew’s immediate actions to remove the fuel and oxygen sources for the fire helped limit the fire damage and extinguish the fire.

The captain informed the Coast Guard that the cause of the fire was a ruptured hydraulic line on the steering pump on the port side, which subsequently released flammable
Hydraulic oil is sprayed onto the hot exhaust manifold and turbocharger of the main drive engine and ignited.

After the hydraulic steering system was reconditioned in late 2022, no issues were reported other than a few minor hydraulic leaks that required tightening of fittings or connections. The captain said no modifications were made to the steering gear after installation. The burst hose was manufactured on October 7, 2018. It is unknown when this hose was installed; however, since the manufacture date predates the refurbishment work by 4 years, it is unlikely that the older hose was installed during the 2022 refurbishment.

Conclusions

Probable cause

The National Transportation Safety Board determines that the probable cause of the fire aboard the tug Desperado was a hydraulic hose, which probably
exceeded its bend radius, which eventually caused the hose to rupture, causing hydraulic oil to spray onto a hot engine exhaust manifold and turbocharger and
ignite.

lessons learned

Follow Manufacturer’s Instructions for Installing Hydraulic Hoses Mariners and technicians who design, install, and maintain systems should follow manufacturer’s instructions on the minimum bend radius for hydraulic hoses. The minimum bend radius is the radius below which an object cannot (or should not) be bent. Bending or kinking a hose to a radius smaller than the recommended minimum radius, or subjecting a hose to tension or torque, can place excessive stress on the hose and severely reduce its compressive strength. Tight spaces can cause a hose to bend severely around corners. The extension and retraction of a machine or cylinder can also bend a hose. Hoses connected to moving parts can bend more than a hose in or near the stationary position of a machine. Measures to prevent hose damage or failure include clamping a hose for support, rerouting a hose assembly by adding fittings and adapters, and using a hose with more reinforcement (two braids instead of one braid).