What happened
The aircraft experienced a structural failure involving the separation of a flap vane while it was on final approach to land. Specifically, approximately 50 inches of the right flap vane detached from the wing structure during this phase of flight. The separated component fell from the aircraft and struck a parked automobile located on the street below, causing slight damage to the vehicle.
The pilot continued the approach and completed an uneventful landing at the destination airport. The incident was not immediately observed by the flight crew or air traffic control. It came to light only after a local resident noticed the debris and contacted authorities to report the fallen article.
The investigation
An examination of the failure mode revealed that the separation was caused by delamination of the vane material, which resulted from moisture ingestion into the structure. Investigators noted that a previous skin repair had been performed on this specific component. Technical analysis determined that the bond used in that repair failed due to inadequate surface preparation and insufficient pressure during the bonding process.
The investigation also highlighted procedural gaps in maintenance oversight. While all DC-10 operators were notified of the failure via telex, the identity of the facility that performed the original bond repair could not be determined.