The explosion was triggered Causation by the `` catastrophic '' failure of a heat exchanger .

The U.S. Occupational Safety and Health Administration ( OSHA ) and the U.S. Chemical Safety and Hazard Investigation Board ( CSB ) launched investigations Scrutiny to determine Deciding how and why the heat exchanger failed .

Rafael Moure-Eraso , CSB chair , addressing Expressing_publicly the U.S. Senate Committee on Environment and Public Works on June 27 , said Communication : `` there was a catastrophic failure involving Participation a heat exchanger and associated Collaboration piping which broke loose from a distillation tower ... It is too soon in our investigation to tell why the equipment failure occurred Coming_to_be . ''

Ice crystals in the jet fuel were blamed Judgment_communication as the cause Causation of the accident Catastrophe , clogging Filling the fuel-oil heat exchanger ( FOHE ) of each engine .