Accident Board Recommendations

Following are select NTSB recommendations specific to the fan hub failure excerpted from the NTSB report:

  • Form a task force to evaluate the limitations of the blue etch anodize and other post manufacturing etch processes and develop ways to improve the likelihood that abnormal microstructure will be detected. (A-98-09)
  • Inform all manufacturers of titanium rotating engine components of the potential that current boring and honing specifications may not be sufficient to remove potential defects from holes and ask them to reevaluate their manufacturing specifications and procedures with this in mind. (A-98-10)
  • Establish and require adherence to a uniform set of standards for materials and procedures used in the cleaning, drying, processing, and handling of parts in the fluorescent penetrant inspection process. In establishing those standards, the FAA should do the following:
    • Review the efficacy of drying procedures for aqueously cleaned rotating engine parts being prepared for fluorescent penetrant inspections; (A-98-11)
    • Determine whether flash drying alone is a sufficiently reliable method; (A-98-12)
    • Address the need to ensure the fullest possible coverage of dry developer powder, particularly along hole walls; (A-98-13)
    • Address the need for a formal system to track and control development times; (A-98-14)
    • Address the need for fixtures that minimize manual handling of the part without visually masking large surfaces of the part. (A-98-15)
  • Require that all heavy rotating titanium engine components (including the JT8D-200 series fan hubs) receive appropriate nondestructive testing inspections (multiple inspections, if needed) based on probability of detection data at intervals in the component's service life, such that if a crack exists, but is not detected during the first inspection, it will receive a second inspection before it can propagate to failure; assuming that a crack may begin to propagate immediately after being put into service, as it did in the July 6, 1996, accident at Pensacola, Florida, and in the July 19, 1989, United Airlines accident at Sioux City, Iowa. (A-98-19)
  • Require, as an interim measure, pending implementation of Safety Recommendation A-98-19, that critical rotating titanium engine components that have been in service for at least 2 years receive a fluorescent penetrant inspection, eddy current, and ultrasonic inspection of the high-stress areas at the engine's next shop visit or within 2 years from the date of this recommendation, whichever occurs first. (A-98-20)

The complete text of the NTSB recommendations is available at the following link: NTSB Recommendations

Back to top