Originally Posted by
TowerDog
Yeah but the AA tail was damaged in production, then “repaired” before delivery.
Yeas, but the NTSB tested the materials and found they were still exceeding design strength.
The National Transportation Safety Board determines that the probable cause of this accident was the in-flight separation of the vertical stabilizer as a result of the loads beyond ultimate design that were created by the first officer’s unnecessary and excessive rudder pedal inputs. ---
NASA-Langley’s and Airbus’ FEA models showed that the stress and strain profiles of the right rear lug at the time of vertical stabilizer separation were equivalent to those of the full-scale certification test at failure, and NASA’s PFA results showed that the failure load, failure mode, and location of failure initiation for the accident condition were equivalent to those of the full-scale certification test. ---
The stresses developed exceeded the strength values for the CFRP material used in the manufacturing of the lugs; thus, the accident lug and the tested lugs fractured because of a tensile static overload. The accident reports has the full details on that in sections 1.16.3 and 1.16.4.