A NON-INJURY METHANE IGNITION IN THE #2 ENTRY, INBY #23 CROSSCUT OF 8 WEST. A TRUSS LEG WAS BEING DRILLED THRU A HOLE IN ROOF PAN. AN EXTENSION WAS ADDED TO THE DRILL STEEL. THE SPINNER WRENCH RUBBED ON THE ROOF PAN IGNITING CH4 BLEEDER COMING OUT OF DRILL HOLE. THE FLAME TRAVELLED 15' TO FACE, THEN WENT OUT ON ITS OWN