The June 1 crash of an Air France Airbus A-330 flying from Rio de Janeiro to Paris raises issues of both the A-330’s suitability as a replacement for the United States military’s aerial refueling fleet and the safety of Airbus airplanes in general. A series of incidents have occurred involving Airbus airplanes related to structural failures of the vertical tail fin and rudders and computer problems with the plane’s fly-by-wire systems of aircraft built by European Aeronautic Defense and Space.
The investigation into the Air France Flight 447 crash continues, but the recovery of the airplane’s vertical tail fin and rudder, found 30 to 50 miles from the general debris field in a relatively undamaged condition strongly indicates that the tail fin and rudder separated from the airplane prior to impact with the ocean. It is only one of a number of structural failure incidents involving Airbus 300-series airplanes.
George Larson, editor emeritus of Smithsonian Air & Space Magazine reported the comments of an aircraft maintenance professional in Opa Locka, Florida. After years spent dismantling dozens of large aircraft built by the major manufacturers he told Larson that, “Airbus products are the flimsiest and most poorly designed as far as airframe structure is concerned” and “The vertical fin along with the composite hinges on the rudder and elevators is the worst example of structural use of composites I have ever seen.”
Previous Airbus Incidents
In November 2001, eyewitnesses saw American Airlines Flight 587, an Airbus-300, shed its vertical stabilizer, the tail fin and rudder, in flight. The airplane crashed in a neighborhood of Queens in New York City. The National Transportation Safety Board investigation said the airplane encountered wake turbulence from another aircraft and that the copilot flying the Airbus over-controlled the airplane’s rudder, which was not subject to computer limits at slow airspeeds, inflicting extreme loads on the structure that failed. The Air France crash has pilots and experts questioning the NTSB’s finding of pilot error in this and other crashes.
In May 1997, American Airlines Flight 903 experienced a non-fatal stall/upset incident involving the use of the rudder on an Airbus A300-600. Investigators determined that abrupt movements of the rudder “can lead to a rapid loss of controlled flight” and might inflict forces capable of ripping the vertical fin off the airframe. An immediate inspection of the tail found no damage, but subsequent detailed inspections of that airframe found cracks in the composite structure that led to the replacement of the tail.
In 2002, a FedEx pilot flying an Airbus A-300 freighter complained about uncommanded movements of the airplane’s rudder while in flight. Ground tests by FedEx maintenance crews found that the hydraulic actuators that swing the rudder left and right exceeded the rudder travel limits and tore holes in the structure in the same area where other Airbus rudders have detached from airplanes in flight.
In March 2005, Air Transat Flight 961, an Airbus A-310, was en route from Cuba to Quebec in level cruise flight when the rudder fell away from the airplane over the Caribbean Ocean. The airplane was able to return for a safe landing, but the incident added to questions about EADS’ use of composite construction technology, inspection methods, and computer controlled flight systems. There are at least two other Airbus 300-series aircraft that went down in oceans due to still unexplained circumstances, but the tail fin of one of those airplanes was found floating near where the airplane crashed.
In-flight structural failures aside, computer problems also resulted in Airbus incidents. An Airbus flyby at the 1988 Paris Air Show with the landing gear extended ended in a fatal crash because the computer decided the airplane was landing and failed to increase engine power when the pilot pushed the throttles up. A brand new Airbus A-340 delivered to Etihad Airlines was destroyed in 2007 when the crew, doing full power engine run-ups in a parked airplane silenced an alarm warning that the airplane was not properly configured for takeoff. The computer decided the airplane was attempting to land with the parking brake set and released the brakes. The airplane jumped the wheel chocks and collided with a concrete wall.
While these incidents afflicted different models of airplanes, all the Airbus 300-series aircraft, including the EADS A-330 tanker variant, share similar fly-by-wire systems, composite material components and assembly methods. They are mounting evidence that the construction methods and computer systems utilized by the EADS, the consortium that manufactures the A-330 Multi Role Tanker Transport, make it unsuitable for the tanker role.
“It is valid to consider that inappropriate sensor inputs led to inappropriate computer outputs in these incidents,” said Edward J. Dugan, a retired airline pilot who flew fighters for the Air Force and served as a certified crash investigator. “The evidence that’s available based on the history of Airbus airplanes should be a major concern and it sounds like a good case against the selection of the A-330 tanker.”
Size and Mission Flexibility
The size and weight of the Airbus A-330 limits the number of airfields the plane can safely operate in and out of, and how many aircraft can occupy the airport’s runways, taxiways and parking aprons. Bigger airplanes require more room for ground operations and the A-330 is 81 percent larger than the aging KC-135s. It carries only 20 percent more fuel than the KC-135 and the Airbus tanker lacks the capability to provide aerial refueling for all the aircraft in the military’s inventory.
“We need replacement tankers badly,” Dugan said, “but acquiring fewer airframes with bigger tanks is a huge waste of money because mission flexibility favors a fleet of smaller tankers.”
The Airbus A-330 lacks the speed and acceleration to perform the overrun and breakaway maneuvers required to execute mid-air refueling operations. There are other performance differences to consider, particularly concerns about the abrupt maneuvers tanker aircraft must be able to perform, even when the air is turbulent and the aircraft, flying in close proximity, are caught in the additional wake turbulence generated by an aircraft’s passage through the air.
From personal experience as a passenger in the jump seat of an Air Force KC-10 tanker, it can be a rough ride when the heavily-loaded airplane slews around in the bow wave of another tanker and the pilot uses heavy and abrupt applications of rudder, elevator and ailerons getting in to position to hook up and pass gas. Good pilots make tight formation flight, a staple of aerial refueling, look easy but there is nothing easy about it all. After watching military flyers work up a sweat manipulating the controls to maneuver in tight formation for a hook up, it’s disconcerting to consider that future tanker pilots will be at the mercy of computers second-guessing their actions and that if the computer receives incorrect data, the airplane could be torn apart in midair.
“As a pilot,” Dugan said, “I expect the airplane I’m flying to be able to reach its maximum speed and still be able fully deflect the control surfaces without the airplane coming apart.”
The Airbus aircraft competing for the $40 million contract uses a fly-by-wire flight control system that, unlike the computer controlled systems of other manufacturers’ airplanes, prevents the pilot from making control inputs that might overstress the airframe. In an emergency situation, the pilot of the Airbus is along for the ride if the computers do not agree with the pilot’s control inputs. Couple the Airbus computer system with the growing body of evidence that the Airbus system has repeatedly failed to prevent overstress situations from happening due to improper sensor inputs and the airplane could be a disaster waiting for the right set of circumstances to occur.
A statement in The Observer reported that more than a few airline pilots flying for operations using Airbus and other manufacturers’ airplanes have asked to be reassigned to flying duties in aircraft other than Airbus planes despite the lost wages of time away from work during retraining for other aircraft types.
Tanker aircraft missions are stressful to both the aircraft and its crew in terms of the hours flown, the conditions of flight and the maneuvers required to complete the mission. When the situation is critical, military personnel count on having the right equipment for the job. The Airbus A-330 is simply not the right choice.