"They were scheduled for those," Main answered. "As far as were they all completed, that's something that will be assessed."
In a prepared statement issued after the hearing, MSHA said agency officials have "found no evidence that we missed the timeframe for completing spot inspections at UBB, based on the procedures in place."
But, MSHA said, an "internal review team will examine MSHA records thoroughly to ensure that we have met those inspection requirements."
Under federal law, MSHA is required to conduct frequent spot inspections -- sometimes as frequently as every 5 days, depending on methane levels -- to check on potential ventilation problems at mines that liberate large amounts of the explosive gas.
Agency records indicate MSHA completed these required periodic spot inspections in January, February and March 2010.
The last spot inspection prior to the explosion was on March 25, and another spot inspection was not performed until April 12.
MSHA spokeswoman Amy Louviere said that the agency had Upper Big Branch on a schedule for spot inspections every 10 days from January through the end of March 2010. Sometime during that period, agency officials found higher levels of methane, and the mine's spot inspection frequency was to be increased to every five days starting April 1, Louviere said.
Louviere said that MSHA believes a new spot inspection was due to be conducted sometime between April 2 and April 6. The explosion occurred on April 5.
"We don't live in a perfect world," Main told lawmakers. "We wish that we did. With all of the pieces that we inspect, there are some quality improvements that we could make."
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.