A Metro train arrives at the L’Enfant Plaza station in Washington on Jan. 13, 2015. (Pablo Martinez Monsivais/AP)

Metro officials fired a senior mechanic just weeks after the L’Enfant Plaza smoke incident last year, alleging that he failed to properly inspect a tunnel fan, falsified an inspection report, and later lied about it to investigators.

But now, the largest union representing Metro workers is fighting the transit agency to have the mechanic reinstated.

Seyoum Haile, a 13-year Metro veteran, was terminated one month after the January 2015 incident that resulted in the death of a passenger — but arbitrators said he should be suspended instead, and now the Amalgamated Transit Union Local 689 is suing to get him back on the job.

Metro General Manager Paul Wiedefeld vowed Thursday to fight the April arbitrators’ decision in court.

The legal back-and-forth comes as a public test of Metro’s commitment to its newfound no-excuses safety culture in the aftermath of Wiedefeld’s promises to clean house and swiftly ax employees who disregard safety.

Metro demonstrates operation of fan shafts that allow a free flow of clean air through the underground tunnel network. In the event of an emergency, like the underground fire on Jan. 12, 2015, which left one rider dead from smoke inhalation, these air channels are critical to the safe passage of riders. ​The video was taken in a tunnel-fan shaft between the Fort Totten and Georgia Avenue-Petworth stations. (Dakota Fine/The Washington Post)

“We strongly disagree with the arbitration award given the employee’s egregious acts,” Wiedefeld said in a statement. “We intend to file a motion in District Court to vacate the arbitration award.”

According to court documents, Haile was a general equipment mechanic responsible for inspecting a tunnel fan that was used during the L’Enfant Plaza smoke crisis that resulted in the death of 61-year-old Carol Glover and the hospitalization of scores of other passengers.

Metro managers and arbitrators both acknowledged that Haile is not responsible for the death and injuries that occurred during the L’Enfant Plaza episode, because the circuit board for the fan in question burned out after it had been running for several hours — after passengers were removed from the tunnel.

That same fan had also been inspected the month later by someone else.

But Metro officials stated that they chose to terminate Haile — “a respected senior mechanic,” according to the arbitrators’ report — because he failed to inspect the tunnel fan in November 2014.

The inspection process requires a mechanic to radio into the command center to request that the fans are turned on remotely; in this case, when an employee in the command center could not locate the correct fan, Haile moved on to another site to try a different fan and did not return to the original fan. Haile indicated on a written report that he had completed the inspection, and later lied to Metro officials during the investigation about falsifying an inspection report, according to documents filed in federal court in the District.

“Specifically, the . . . inspection checklist you submitted affirmed a successful remote testing of the tunnel fans in both exhaust and supply modes,” a Metro equipment maintenance superintendent wrote in a memo to Haile. “However, the [Rail Operations Control Center] computer log did not reflect either of those operations taking place. . . . A review of the ROCC computer log reveals that no commands were given to operate the fans remotely.”

Investigators tasked with interviewing Metro employees about what went wrong the day of the L’Enfant Plaza incident reported that Haile continued to assert that he had successfully completed the inspection, according to the lawsuit filed Wednesday.

“During the course of my investigation,” the superintendent added, “you were given several opportunities to provide accurate and forthright information and on each occasion you chose not to do so. You have shown a pattern of routinely falsifying [preventive maintenance] records for [the] fan shaft, a critical fire/life-safety system.”

Metro officials maintained that Haile’s falsified report was part of a wider trend: In 2009, he was disciplined for leaving work without permission.

Metro officials fired Haile in February 2015. But ATU Local 689 pushed for the case to be heard by an arbitration board.

Haile told arbitrators that he had submitted an inspection report in November 2014 that left a blank spot for the inspection of the tunnel fan — at the time, a common occurrence among mechanics — and testified that a supervisor had pressured him to later check off the tunnel-fan inspection in the hours after the L’Enfant Plaza smoke episode, before he was aware that there had been a serious incident.

“They trick us. . . . They call us to fill out this paper to cover themselves,” Haile testified to the arbitrators, recalling his dialogue with the supervisor. “When we came from the field . . . [I said,] I can’t remember all this. . . . We don’t know this, I just guessing. But we knew right away after we left there was an accident. The lead man and the supervisor, to cover themselves, they forced us to put it.”

Union representatives argued that Haile’s mistake was just one of many by many Metro employees that contributed to the disastrous consequences of the smoke incident. They said he was “made out to be a scapegoat [for] institutional failings.”

Another employee who had falsified a similar report was suspended for three days.

In its May ruling regarding the cause of the Jan. 12, 2015, incident, the National Transportation Safety Board said a slew of chronic failures affecting the transit system, including a lax safety culture, poor maintenance and a failure to learn from previous disasters all contributed to the L’Enfant calamity.

“Quite simply, they have not been willing to learn from prior events,” NTSB member Robert L. Sumwalt said at the time.

After hearing both sides, arbitrators concluded that Metro had acted too harshly, and that Haile deserved to keep his job, with an 180-day unpaid suspension and no loss of benefits or seniority.

“The grievant’s misconduct was serious,” wrote arbitrator Ezio E. Borchini. “However, in light of all of the evidence, it was not so serious as to be disruptive of the employment relationship. The penalty must be rehabilitative, rather than punitive.”

Borchini added that a significant amount of the culpability lies with Metro.

As a whole, he wrote, Metro “condoned blank checklists, and even accepted blank replacement checklists, through August 2014, and provided pre-signed daily activity reports.”

The union is demanding that Haile be reinstated at his job within 10 days. Metro is required to submit a response to the complaint within three weeks.