An NPR News investigation has documented a dangerous and potentially illegal act at the Upper Big Branch mine in West Virginia two months before a massive April explosion killed 29 mine workers.

On Feb. 13, an electrician deliberately disabled a methane gas monitor on a continuous mining machine because the monitor repeatedly shut down the machine.

Three witnesses say the electrician was ordered by a mine supervisor to "bridge" the automatic shutoff mechanism in the monitor.

Methane monitors are mounted on the massive, 30-foot-long continuous miners because explosive gas can collect in pockets near the roofs of mines. Methane can be released as the machine cuts into rock and coal. The spinning carbide teeth that do the cutting send sparks flying when they cut into rock. The sparks and the gas are an explosive mix, so the methane monitor is designed to signal a warning and automatically shut down the machine when gas approaches dangerous concentrations.

"Everybody was getting mad because the continuous miner kept shutting off because there was methane," recalls Ricky Lee Campbell, a 24-year-old coal shuttle driver and roof bolter who witnessed the incident. "So, they shut the section down and the electrician got into the methane detector box and rewired it so we could continue to run coal."

The continuous miner was working in an entryway about three miles from the location of the deadly explosion in April. Campbell and other mine workers were getting the section ready for mining. The continuous miner was cutting into the roof to make way for a conveyor belt and was cutting into both rock and coal, according to Campbell.

"I asked them, 'What are you doing?' " Campbell says. "And they told me, 'We're bridging a methane detector. We're bypassing it,' is what they said."

Witnesses Corroborate Bridging

Two other witnesses confirm the bridging incident. Both asked not to be named because they fear for their jobs, their families and their futures. Campbell has already been fired by Upper Big Branch owner Massey Energy. He has a whistle-blower claim pending against the company based on other complaints about safety. Massey Energy has called the claim groundless and says Campbell's dismissal was warranted.

All three witnesses are clear about what happened on that cold and snowy day in February in the Coal River Valley of West Virginia. The electrician was ordered to bridge the monitor by the mine supervisor but he didnt know how to do it. So the supervisor called to the surface to find someone who could describe the procedure.

The process took more than an hour, as the electrician dismantled the monitor and used a wire to circumvent the device that disables the mining machine.

"The electrician said, 'Please don't say nothing,' " Campbell remembers, adding the electrician was afraid he would lose his state certification. "He knew it was dangerous. He knew he shouldn't have been doing it. But when somebody higher up [is] telling you to do something, you're going to do what they say. And he just [did] his job and [did] what they said to do."

The electrician does not deny the incident happened but declined to be interviewed.

Misconception Among Miners

Two of the witnesses say they don't believe excessive methane gas forced the monitor to shut down the mining machine. They believe the monitor was simply malfunctioning, which is a common problem underground.

The witnesses also repeated a widespread misconception about what is and isn't permissible when monitors malfunction. Clay Mullins, a former Upper Big Branch foreman whose brother Rex died in the April explosion, recounted that belief in an unrelated interview in June.

"It does say in the law that if you got a methane monitor malfunction, you can bridge it out and you can run that machine for 24 hours," Mullins said. "But the operator has to carry a [hand-held] methane detector, and he has to take [readings] ... every 15 minutes."

NPR heard this repeatedly during a three-month-long investigation of the Upper Big Branch disaster. But "it's not permitted, and I think it is clearly in violation of the law," says Edward Clair, who retired last year after 22 years as the chief attorney for the Mine Safety and Health Administration.

The law, Clair says, requires working methane monitors on all mining machines cutting rock and coal. He says there are no exceptions in the law or in mining regulations.

Hand-held monitors are also no substitute for the methane detectors mounted on mining machines as close to the cutting surface as possible, according to Bruce Dial, a former federal mine safety inspector and trainer. That's because the mining machine is nearly as long as a school bus and mine workers are behind it as it cuts.

"They are probably 25 to 30 feet back from the face," Dial says. "That means you've got 25 or 30 feet of area that could be building up methane. You could have an explosive atmosphere before you ever know about it 30 feet back."

In a statement to NPR, the Mine Safety and Health Administration says these actions, if true, "would clearly violate the law and jeopardize the lives and safety of miners."

"What makes it criminal is that somebody actively defeats the safety protection, and that should be prosecuted," says Clair, the former MSHA solicitor. "You've put production over the safety of your employees."

'Methane Monitor Is Life And Death'

Mullins, the former foreman at Upper Big Branch, was more direct in June when asked generically about bridging monitors.

"That's something I would not tolerate," Mullins said. "Because the methane monitor is life and death. That's a problem you correct right away."

If a mine has monitors on hand, replacing a malfunctioning monitor might take a couple of hours. The shutdown would be longer if no replacement is available.

Mullins says he never saw a methane monitor bridged in his eight years at the Upper Big Branch mine. Most of the dozen Upper Big Branch miners NPR spoke with say the same thing. A few, though, say they've seen bridging at the mine, including a rudimentary variation that involves placing a plastic bag over the sniffer on the device.

The February incident raises an important question as investigators try to determine the cause of the deadly explosion on April 5. Was the monitor bridging incident isolated? Could something similar have happened the morning of April 5 in the vicinity of the blast?

"It wasn't where the actual explosion occurred in that section of the mine," says former federal inspector Dial. "But it still shows me that the attitude of the company, the attitude of the foreman and whoever else knew about this ... is the attitude that production is the most important."

Massey Responds

Massey Energy confirms in a statement from spokesman Jeff Gillenwater that the Feb. 13 incident took place. But Gillenwater writes "the supervisor did not order an electrician to bridge a methane monitor on a continuous miner 'to keep the mining machine from shutting off while operating.' "

Instead, Gillenwater says, "The methane monitor was bypassed in order to move the miner from the area that did not have roof support to a safer area for repair."

That is a legitimate reason for bridging a methane monitor. But witnesses insist that the mining machine continued to cut rock, which is not permitted.

Gillenwater also says "Massey strongly forbids any improper conduct relating to any and all safety devices." And he echoes Stan Suboleski, a Massey board director and former chief operating officer, who told NPR in May that he was astounded at claims company miners disabled methane monitors, "because the company would never condone action like that. We would immediately fire anybody ... if we heard of an action like that occurring. It's just not tolerated in the company."

Under Investigation

The FBI has been actively investigating the incident for months. And Ricky Lee Campbell has just received a subpoena to appear before a federal grand jury in Charleston, W.Va., in two weeks. The investigations and the witness accounts have former mine safety and health solicitor Clair thinking this case of monitor tampering is neither benign nor isolated.

"You can't help thinking," Clair says, "that if you've discovered it one time that it's indicative of an attitude of noncompliance, thumbing your nose at the law, within that company."

NPR's Frank Langfitt contributed to this report [Copyright 2010 National Public Radio]