Attrition: The Thick And Thin Of It


January 18, 2013: It was recently and very quietly revealed that the manufacturer of the American F-15 fighter would give the U.S. Air Force a million dollars of F-15 spare parts, free of charge, in compensation for the defective parts they provided that caused an F-15 to come apart in the air in 2007. In that accident the front part of the jet (forward of the cockpit) separated from the rest of the aircraft. The pilot was able to eject safely but was slightly injured in the process.

As a result of losing this elderly F-15, the air force quickly grounded 442 older F-15C/D fighters for over a month so that all could be checked for metal fatigue. This was more common than defective parts, which was eventually found to be the cause of the 2007 accident. Meanwhile, over 400 F-15s each underwent 12-20 hours of inspections. Special attention was paid to the longerons  (metal support beams inside the forward fuselage, which hold the cockpit in place) as one of these failing was quickly noted as the cause of the accident. The longeron in question was eventually discovered to be defective, not suffering from old age. The inspections of the older F-15s found substandard parts in 182 aircraft. Boeing (the manufacturer) eventually admitted that it had built over a hundred F-15s using longerons that were not 2.5mm thick, as specified, but in some cases only one millimeter thick. That apparently worked when the F-15s were new but age was not kind to the thinner metal and it eventually broke. Thicker stuff apparently would not have failed because of age.

The inspections alone cost over a million dollars and the cost of the lost F-15 was more than $20 million. The investigation cost several million dollars as well.

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