Honolulu’s rail passenger cars recently failed a fire-resistance test, signaling another potential defect that could result in delays — but project officials say the test was not run properly and needs further evaluation.

The trains’ manufacturer, Hitachi-owned Ansaldo Honolulu JV, had samples of the vehicles’ floor and roofing materials tested in February to make sure they complied with federal standards, according to Robert Good, a senior project officer for the rail project.

Those roofs and floors should be able to withstand fire for at least 20 minutes in order for passengers to evacuate, Good told the Honolulu Authority for Rapid Transportation board Friday. Instead, flames started to enter the sample passenger compartment at 14 minutes and 30 seconds — a clear failure.

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However, data shows that too much heat was fired onto those train floor and roof materials too early, raising the temperature too quickly and potentially affecting the outcome of the test, Good said, adding the procedure was done manually using a furnace in a laboratory in San Antonio, Texas.

“It should have been a fully automated flame-control test,” said Krishniah Murthy, a senior advisor for HART and the agency’s former interim director. “The guy operating it manually — he can’t control the flames.”

Still, HART executives said they need to be sure the cars are safe. Ansaldo “submitted these to us and we said, ‘No, it’s not acceptable,'” Murthy said.

It remains unclear whether the fire-test problem will affect the city’s goal to launch interim service along the rail line, from the fields east of Kapolei to Aloha Stadium, in December 2020.

For that to happen, HART will need 10 of its four-car trains ready to run, Murthy said. Currently, the agency has six four-car trains on-island, according to HART spokesman Bill Brennan.

“They don’t think it’ll be a problem, based on the conversations we’ve had so far,” Murthy said.

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Ansaldo now plans to run further “small-scale” tests in April and then “large-scale” tests in May, Good said. The May tests will take place in Italy, where the train parts are being manufactured, and Ansaldo will cut up one of its existing car shells to provide the samples, he said.

If those tests have the same result as the test in Texas, then HART and Ansaldo will move to “Plan B,” Good said.

That could mean changing the style of fire-resistant coating applied to the cars, or installing extra plating under the carriages, he said. Murthy said HART would want to avoid making the cars heavier, if possible.

Good, who has more than 50 years of experience on rail projects, said he’s seen train cars fail fire tests before “but not so far along in the build.”

Ansaldo uses the same materials for its trains running in the Middle East and in Europe, so the train firm assumed the materials would work fine for Hawaii as well and didn’t see the need to run those tests sooner, Murthy said.

“They were very confident the test will be OK,” he said Friday.

The rest of Ansaldo’s 20 driverless, four-car trains for Honolulu — the first of their kind to be used for any major transit system in the U.S. — are currently being manufactured in Italy and Pittsburg, Calif.

Several of the initial vehicles assembled had defects in the hollow, metal beams that helped form the car shell, called “aluminum extrusions.” There were concerns those defects could cause delays, but Ansaldo and Hitachi have since resolved the problem, Murthy said.

Read Good’s PowerPoint presentation to the HART board here: