Accident Board Recommendations

The NTSB issued nine safety recommendations to the FAA. Select the link to view the detailed NTSB Safety Recommendations and corresponding FAA responses.

Three of the recommendations (A-73-116, -117, and -118) pertain to the inspection and maintenance of digital flight data recorders. During the accident investigation, the digital flight data recorder from the National Airlines airplane was found to be defective and no meaningful data could be retrieved.

Photo of failed engine
Photo of failed engine

Five recommendations (A-74-7 thru A-74-11) concern the passenger and portable oxygen systems installed in the DC-10. The accident revealed deficiencies relative to the installation of the cabin oxygen generating units, functionality of the system and accessibility of portable oxygen units in the cabin. In addition, it addressed the possibility that separate pressure losses of different magnitudes may occur on the DC-10 and the need of separate aneroid devices.

One final recommendation pertains to the assessment of aircraft damage by flight crews during in-flight emergencies. The NTSB investigation identified that National Airlines did not have a procedure for crew members to assess the damage to the airplane in an emergency situation. After the emergency was under initial control, the cockpit crew did not assess the extent of damage to the airplane or the condition in the cabin.

Immediately following the accident, the FAA issued a telegraphic Airworthiness Directive (AD) that applied to all DC-10 aircraft. The AD required inspection of the engine nose cowl mounting integrity and correction of any possible deficiencies. Also, it was recognized early that fan-tip rub was a necessary condition in the sequence of events that brought about the loss of the fan blades.

As a preventive measure against the recurrence of this type of condition, the fan blade tip-to-shroud clearances were increased. As backup for the possibility of blade-tip rub even after the tip clearance was modified, an extensive development, testing, and production program was established to increase the capabilities of the blade retention devices. The blade retention devices were redesigned with increased capability of more than three times the original configuration. These modified blade retention devices were incorporated in all revenue service engines.

In the accident report, the NTSB addressed the flight crew performance of an experiment with the auto-throttle/speed control system. The NTSB stressed that the operator and the pilot in command should be fully cognizant of their operational responsibilities to conduct the flight in a professional manner and not to conduct experiments with aircraft systems in which they have not received specific training or instruction.

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