Centurion Air Cargo Flight 425 landing accident

The Centurion Air Cargo Flight 425 landing accident (Senchurion Ea Kāgo 425-bin chakuriku shippai jiko) was an aviation accident on 13 October 2012 in which a cargo aircraft operated by Centurion Air Cargo failed to land successfully at Viracopos International Airport in Brazil.

As a result, the aircraft's left landing gear (left main gear), wing and engine were damaged, but there were no fatalities or injuries.

Course of the accident

Flight 425 took off from Miami International Airport without incident, and on the night of 13 October the first officer was flying the approach to runway 15 at Viracopos International Airport using the ILS Z procedure. Visibility was good (VMC: visual meteorological conditions), but the wind speed, which had been 20 knots when the tower issued the landing clearance, temporarily rose to 29 knots.

However, at 21:52 UTC (18:52 local time), at the moment the flight touched down at the airport, the left main gear broke, and in that state the aircraft slid, scraping, for more than 800 metres along the runway. As a result the left landing gear, wing and engine were heavily damaged, but the aircraft did not leave the runway and none of the crew were injured.

Infraero, which operated Viracopos International Airport, had to spend nearly 2 days removing the aircraft and reopening the runway.

Accident investigation

The US National Transportation Safety Board and Brazil's Aeronautical Accidents Investigation and Prevention Center launched an investigation. Although the wind speed at the time of the accident was somewhat strong, the landing wind limit in the MD-11 manual was 30 knots, so the wind conditions were found not to have been a limiting factor for the aircraft. In addition, while the MD-11 is certified to land at its maximum limit weight (222,941 kg) with a descent rate of 600 feet per minute, the accident aircraft's weight and descent rate were 197,036 kg and 600 feet per minute respectively, so it was found that there was no problem with the aircraft's landing and that it had been operated correctly.

However, when the aircraft had the accident in 2009 mentioned above and suffered damage to its right main gear, the landing gear was replaced by VARIG Engineering & Maintenance, but the accident investigation committee at the time could not identify from the records the organisation responsible for investigating the damage to the aircraft, identifying the services needed to restore airworthiness, and providing all the services that made that possible in Montevideo. In addition, the aircraft's records had not been examined for the occurrence of other events that might have damaged the structure of the left main gear, and it was possible that the resulting damage had not been repaired by the repair services provided, or had not been detected in the aircraft's subsequent scheduled inspections.

The materials laboratory's examination found a crack in the landing gear, which began at the rear of the cylinder at a connection hole (bolt hole) that was a stress concentration point and reached the front of the cylinder, splitting it in 2. From this, 2 points were derived: that the cylinder failure was due to overload in the cylinder structure, and that signs of a pre-crack originating from the overload condition in the accident 3 years earlier may have acted as a stress concentration point. No evidence of corrosion or fatigue was found.

It was concluded that because of the existence of this pre-crack, even a landing within the aircraft's limits that was not a hard landing could cause a failure of landing gear components and their eventual fracture.

By the time of the Flight 425 accident, the MD-11 had been involved in 14 incidents during landing, and in particular, following the 2010 Lufthansa Cargo Flight 8460 landing accident, Boeing had held meetings with all MD-11 operators to discuss operating and training conditions. After the meetings, in 2011 Boeing revised the landing section of the MD-11 manual to emphasise operational considerations and techniques, with particular focus on approaches with high descent rates.