An investigation into a military plane crash in Spain last month is in the early stages, but investigators already have a theory as to what went wrong: computer data that control the Airbus A400M military carrier's turboprop engines had accidentally been wiped from the system. The files—called "torque calibration parameters"—are installed on an engine's computer and interpret sensor readings on an engine's torque, adjusting the speed of the propellers accordingly. Without the data, an engine can't run as the propellers turn too slowly, reports the BBC. During the plane's first test flight on May 9, three of the four engines froze shortly after takeoff. Four of six on board died in the crash. Sources tell Reuters the data was unintentionally removed while software was being installed at an Airbus facility. Safety checks failed to notice the problem, and pilots were only alerted when they reached 400 feet in the air.
The plane, which cost $22.5 billion to develop, was designed in 2009 to inform pilots of an issue at such a height, rather than on the ground, partly because the likelihood of a failure was small. That system was again approved last year. "Nobody imagined a problem like this could happen to three engines," a source says. The plane had been purchased by Turkey and was on a pre-delivery test flight, and several other countries have since received A400M deliveries. Spain, Britain, Germany, Turkey, and Malaysia have all grounded the planes, reports the Local. Though Spain has banned Airbus from flying new A400M models for now, the company will fly a "development" plane at the Paris Air Show next week. "We have complete confidence in the A400M, and we are delighted to fly our demo as planned," a rep says. (Airbus' next plane could be a flying doughnut.)