There are some 1,400 CF6 engines in use worldwide on planes including Boeing 747s, 767s and Airbus 300s, and there are four thousand CF6-equipped airplane takeoffs each day. It's a common engine, but it has had problems. In a sternly worded report last December, the NTSB warned that the CF6 engines presented a potentially "catastrophic" threat. The NTSB recommended to the FAA that it take action, including a review of the design of the engine's high pressure turbine disc because of a number of dangerous incidents in the past few years.
The FAA this spring began requiring operators to replace the engine shrouds on the engines. That action followed one in September, 2000, when the FAA issued an emergency directive to shorten inspection intervals for the CF6. The order had been prompted by a troubling incident two months earlier. A Varig Airlines 767 had to abort a takeoff after one of its CF6 engines had what is called an 'uncontained' failure, in which the engine partially disintegrated and metal flew out of the engine's casing. According to reports, there have been 61 uncontained low-pressure turbine failures with CF6 engines since 1993.
Another incident which worried experts took place in April 1999 and involved the abrupt emergency landing of a Brussels-bound Continental Airlines DC-10 flight which had just taken off from Newark International Airport. The right CF6 engine was seriously damaged when it suffered an uncontained failure. Last September, a US Airways CF6 engine undergoing a maintenance check blew apart and scattered parts across the tarmac and even into a nearby river.