United Airlines grounded all 52 of its 777s after disclosing to US FAA that a review of its maintenance records revealed that required checks on cargo fire suppression systems were "not performed." UA cancelled an estimated 38 flights yesterday as it conducted the inspections. It said one of five bottles in the 777's cargo fire suppression systems had been overlooked during routine maintenance checks. "This system is regularly tested as part of the preflight safety checks," UA said. "These checks [now being conducted] are related to compliance. United will not operate these aircraft until the tests are complete. . .We apologize for any inconvenience." It granted full refunds to passengers for cancelled flights. The grounding follows similar moves by other US airlines in the midst of increased scrutiny of FAA's safety oversight, the focus of a Congressional hearing scheduled for today (ATWOnline, April 2). by Aaron Karp