A hydraulic hose failure set off a fire on a fishing vessel off the Massachusetts coast last year, leading to a helicopter rescue of the five-member crew, the National Transportation Safety Board said in a report released last month.

The fire broke out on the trawler Nobska as the crew was groundfishing in Georges Bank, about 80 miles east of Cape Cod, on April 30, 2021, the agency said in a statement released Thursday. A Coast Guard helicopter was able to reach the burning vessel and hoisted members of the crew from the water, the report said. No injuries were reported.

The vessel, which was built in 1988 and was homeported in New Bedford, was deemed a total loss at an estimated value of $2.4 million, the statement said. The fire that ultimately consumed the Nobska was the second one on the vessel that day.

“The NTSB determined the probable cause of the fire aboard the Nobska was a failure of a hydraulic hose within the engine room that allowed hydraulic fluid to spray onto a hot surface, likely the exposed main engine exhaust pipe,” the statement said. “Contributing to the failure of the hydraulic hose was possible heat damage from a fire that occurred earlier in the day.”

Earlier, the crew put out a fire on the lagging of the main engine exhaust pipe in the engine room and found “a ruptured hydraulic hose nearby in the pipe/hose tunnel connecting the engine room to the wheelhouse,” the statement said. The crew replaced the hose with a similarly sized one and the captain, who had 35 years of experience, decided to continue fishing, the statement said.

About four hours later, around 5 p.m., the captain was in the wheelhouse when he noticed black smoke rising from beneath the deck winch-control console. He alerted the crew, “and within moments the wheelhouse area was engulfed in flames,” the statement said.

“The second fire resulted in extensive damage throughout the vessel and was likely the result of another hydraulic hose leak, when atomized fluid contacted a hot surface, most likely the exposed main engine exhaust pipe, and flashed into a fire,” the statement said.

The crew retreated to the vessel’s stern, activated their emergency position indicating radio beacon, and deployed a life raft, the report said. Two Coast Guard aircraft responded to the scene about 6:25 p.m. A rescue swimmer directed the captain and crew into the water, where they were then hoisted into a helicopter, the report said.

The pipe/house tunnel on the vessel was found to lack “any insulation, pipe/cable fire stops, or other barriers to prevent the passage of smoke, heat, and fire — known as structural fire protection,” the report said.

“This type of unprotected vertical tunnel has the potential to provide a pathway for fires to spread quickly outside of the space of origination,” the report said. “Vessel owners and operators should identify such openings between decks and ensure they are structurally fire protected to prevent the spread of a fire.”

Nick Stoico can be reached at nick.stoico@globe.com. Follow him on Twitter @NickStoico.

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