Three Delta Air Lines jets made emergency landings this weekend despite a tougher maintenance program to address engine problems, airline officials said. The three incidents included two planes on international routes. All ended safely with no injuries, The Wall Street Journal reported Monday. Delta and federal safety officials are investigating the incidents. The incidents included a New York-to-Moscow-bound Delta Boeing 767 with more than 200 people on board, which returned safely to John F. Kennedy International Airport Sunday after losing thrust from its left engine shortly after takeoff. Also on Sunday, pilots of a Boeing 767 traveling from Atlanta to Los Angeles declared an emergency after reporting an engine problem and returned to Atlanta, federal officials said. The Federal Aviation Administration, which is investigating the incident, said the plane scraped its tail during the landing. On Saturday, a Delta Boeing 757 with more than 160 people on aboard had to land in Shannon, Ireland, after an engine problem developed while the plane crossing the Atlantic from Philadelphia. A Delta spokesman said preliminary indications are that a compressor stalled. Last month, a Delta spokesman said in-flight engine shutdowns occurred earlier in the year, attributing the overall increase of maintenance issues to the challenge of combining Delta's maintenance and operations with those of Northwest Airlines as part of the merger of the two carriers, which was completed last year, the Journal said. Spurred by recurring engine issues and an increase in other types of maintenance-related delays, Delta officials several months ago ordered an increase in the frequency of certain inspections, the Journal said. The airline also beefed up the mechanic workforce at some airports and lengthened layover times so more more thorough inspections of some planes between flights could be performed. Source: upi.com