Three airlines have suspended usage of the Airbus A380 superjumbo jetliners after an engine malfunction caused a midair explosion, leaving the plane crippled and forcing it to return to Singapore for an emergency landing. Qantas, with six A380s, and Singapore Airlines, with 11, both grounded their fleets, while Lufthansa canceled one late-night flight. Singapore Airlines resumed A380 flights on Friday morning. An Airbus spokesman conceded it was the most serious problem experienced by the A380, which has been in service since 2007. The plane can carry as many as 800 passengers, and is used by 37 airlines, 20 of which use engines built by Rolls-Royce, the manufacturer of the faulty machinery. None of the 450 people on board were injured. The incident marks another problem for both Qantas, the airline, and Rolls-Royce, the engine manufacturer, which have each had similar setbacks in recent years.