Former Massey Energy CEO Don Blankenship’s defense lawyers returned this morning to their efforts to blame problems at the Upper Big Branch Mine on the U.S. Mine Safety and Health Administration.

Lead defense lawyer Bill Taylor resumed his cross-examination of former Massey ventilation expert Bill Ross with a series of questions about Massey’s dispute in 2009 with MSHA over the use of “belt air” ventilation on a new longwall mining section at UBB.

In doing so, Taylor took Ross right into the heart of Blankenship’s personal theory of the cause of the April 2010 explosion at UBB – an issue that U.S. District Judge Irene Berger has said she would not allow to be debated before the jury.

Ross testified that he felt UBB needed to continue using belt air – in which fresh air intakes double as conveyer belt tunnels – because of the mine’s rate of liberation of explosive methane gas.

Ross said that he “begged” MSHA to allow UBB to continue using belt air but that agency officials were “adamant” they would not approve that type of ventilation for the new longwall section (previous testimony has indicated MSHA only briefly pushed UBB to stop using belt air and reversed that decision when the plan didn’t work).

Assistant U.S. Attorney Steve Ruby objected and Berger sustained the objection when Taylor tried to ask Ross about the details of the “history” of “incidents” at UBB, likely a reference to several methane “outbursts” at the mine.

Blankenship claims the UBB explosion was caused by an uncontrollable methane inundation, not negligence by Massey.

Ross testified that there were dangers to belt air but that UBB’s methane liberation made using the technique necessary.

Ross told the jury, “The possibility of having a fire along the belt line did exist and does exist in all coal mines but it is far outweighed by the risk of having ignition on the face or an explosion.”