New York Times: As crude oil gushes into the Gulf of Mexico for the fourth week, a Congressional investigation said that a safety mechanism that was supposed to seal an undersea well in the event of a sudden pressure release might have failed on April 20 because of a hydraulic leak. Lawmakers disclosed the findings at a hearing before a subcommittee of the House Energy and Commerce Committee on Wednesday, as the White House proposed a package of legislative changes meant to help people affected by …