Howard Berkes and Frank Langfitt at National Public Radio have nailed down a story that other media have been trying to get, with a piece this morning that reports Massey Energy “bridged out” a methane monitor on a mining machine at the Upper Big Branch Mine in Raleigh County.

NPR issued a press release late last night touting its story, and the Pittsburgh Post-Gazette later posted its own account of the incident.

It’s important to remember that the incident described occurred two months prior to the April 5 explosion, and it’s far from clear exactly what happened or what — if anything — this means for what caused the disaster.

Both stories are based, at least in part, on interviews with Ricky Lee Campbell, a Massey miner who witnessed the incident and is in litigation with Massey over his firing following complaints about safety problems.

Here’s the basic story, as outlined by Berkes in the NPR piece:

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.”

Interestingly, not played up nearly as much in the NPR story were comments from Clay Mullins, a former Upper Big Branch miner whose brother, Rex, died in the explosion:

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.

Berkes went on to speculate:

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 Energy issued a statement that confirmed part of the story, but provided this explanation:

We are aware that an incident may have occurred on February 13, 2010 in which a malfunctioning methane monitor was bypassed on a continuous miner in an outby area (not the coal producing face) of the mine that was cutting rock for a belt head. In the process of cutting, the methane monitor became damaged and therefore shut the machine down.

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.” 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.

In fact, newer continuous miners have a “methane monitor malfunction override” system that was designed by Massey Energy and MSHA, that allows the miner’s hydraulics and tram motors to be re-energized from the miner operator’s remote when the methane monitor malfunctions. This system was developed because in the past, miners had been injured or killed while working on equipment in unsupported top.