Incident Overview
During final approach at an altitude of approximately 500 feet above ground level, the right-hand inboard flap vane departed from the airframe. The separation occurred without prior indication and resulted in the loss of the vane and associated components.
Component Failures
Examination of the separated parts revealed that the vane-to-track support, the aft adjustment eccentric, and the spring cartridge stop assembly had separated due to tensile overload. Despite the tensile failure, testing indicated that the tensile properties of the materials did not influence the failure of the vane itself.
Additionally, the support track, the roller support bolt, and the flap support bushing separated due to shear overload. These components exhibited characteristics consistent with shear stress failures.
Investigation Results
A comprehensive testing regimen was conducted to determine the underlying cause of the failures. However, the tests were unable to identify a specific root cause for the separation. The investigation concluded that while the modes of failure were identified as tensile and shear overloads, the reason for the loads exceeding component strength remained undetermined.
The absence of a determined cause precludes definitive recommendations, though the physical evidence has been documented for future reference.