United Airlines grounds 52 777s for checks

United Airlines, a unit of UAL Corp, on Wednesday became the latest major US carrier to ground planes and cancel flights due to questions over aircraft safety checks and maintenance.

United grounded its fleet of 52 Boeing Co 777s and canceled 38 flights after disclosing to the Federal Aviation Administration (FAA) overnight that it did not complete all steps when testing a fire suppression system in the cargo hold. There was conflicting information late in the day about whether extra work was even required.

The disclosure comes just ahead of a congressional hearing on airline inspection practices and the adequacy of FAA oversight. Four of United's rivals have in recent weeks sidelined aircraft and canceled flights for missed inspections and other safety problems.