Washington ( CNN ) -- The failure of General Electric engines on four jet aircraft overseas during the past two years has prompted the National Transportation Safety Board to issue an `` urgent '' recommendation to increase inspections of the engines on U.S. aircraft . None of the incidents resulted in crashes , injuries or fatalities . But in all four cases , engine parts penetrated the engine housing . Such `` uncontained engine failures '' are particularly dangerous because flying engine parts could puncture fuel or hydraulic lines , damage flight surfaces or even penetrate the fuselage and injure passengers . At issue are General Electric CF6-45/50 series jet engines , older engines found on a small number of jets . FAA officials said 373 of the engines are in service in the United States , on a fewer , but unknown , number of planes . The engines are used on some Airbus A300s , Boeing 747s , DC-10s , MD-10s and U.S. Air Force KC-10s . A GE spokeswoman said most of the engines are used on cargo planes . On four occasions , the NTSB said , a rotor imbalance caused rotor disks to fail , leading to the uncontained engine failures . FAA spokeswoman Laura Brown said the FAA is aware of the problem and issued a rule in March requiring inspections of the engines within 50 flights , and repeat inspections every 175 flights thereafter . It also is working on a rule that would add testing of the rotor disks for cracks . But on Thursday , the NTSB issued its urgent recommendation , saying the FAA should require inspections every 15 flights until the disks can be replaced with improved parts . The FAA said the action `` will maintain the safety of the fleet , '' and that it will decide whether to alter the inspection schedule after completing examinations of the engines involved in the recent incidents . GE spokeswoman Deborah Case said GE issued a service bulletin last August advising operators to inspect and monitor the engines . The NTSB recommendation follows these four incidents : . -- July 4 , 2008 : A Saudi Arabian Airlines ( Saudia ) Boeing 747-300 experienced an engine failure after takeoff from Jeddah , Kingdom of Saudi Arabia . -- March 26 , 2009 : An Arrow Cargo McDonnell Douglas DC-10F , about 30 minutes after takeoff from Manaus , Brazil , experienced loss of oil pressure in one engine . The pilots shut down the engine and diverted to Medellin , Colombia . -- December 17 , 2009 : A Jett8 Airlines Cargo Boeing 747-200F was passing through 7,000 feet when the crew members heard a muffled explosion . With one engine losing oil pressure , the airplane returned to land at Changi , Singapore . -- April 10 , 2010 : An ACT Cargo Airbus A300B4 experienced an engine failure while accelerating for takeoff at Manama , Bahrain . The crew declared an emergency , aborted the takeoff , activated the fire-suppression system , and evacuated the airplane . The NTSB is participating in or leading investigations of the four incidents .
Engines on four jet aircraft overseas failed during the past two years . The FAA has been investigating a number of engine failures in recent years, including one that caused an Airbus A320 to crash into the Atlantic Ocean off Cape Cod, At issue are General Electric CF6-45/50 series jet engines , found on a small number of jets . A GE spokeswoman says most of the engines are used on cargo planes .