Description of Driving Event:
Validation of Flight Software for X-34 and L-1011 Carrier Aircraft Flight Separation
Lesson(s) Learned:
The X-34 technology demonstrator program faces safety risks related to the vehicle's separation from the L-1011 carrier aircraft and to the validation of flight software. Moreover, safety functions seem to be distributed among the numerous contractors, subcontractors, and NASA without a clear definition of roles and responsibilities.
Recommendation(s):
NASA should review and assure that adequate attention is focused on the potentially dangerous flight separation maneuver, the thorough and proper validation of flight software, and the pinpointing and integration of safety responsibilities in the X-34 program.
Evidence of Recurrence Control Effectiveness:
Wind tunnel separation tests simulating the separation of the X-34 from the L-1011 have been successfully completed, using scale wind tunnel models of the X-34 and L-1011. The X-34 release mechanism is based on the flight-proven Pegasus release mechanism designed by Orbital Sciences Corporation. The A-1 vehicle will be flown in captive carry mode under the L-1011; additionally, the A-2 vehicle will be flown in dress rehearsal attached to the L-1011.The aerodynamic forces and flying qualities of the combined vehicles will be assessed during these flights. The flight software will be carried through a thorough Verification and Validation testing process by Orbital Sciences Corporation. Performance tests of the X-34 navigation system (hardware and flight software) have already been conducted at the White Sands Missile Range using an aircraft platform. Subjecting the flight software to IV and V remains an option to the program if concerns about the software dictate. In May 1998, Code Q conducted a detailed review of safety and mission assurance processes being used by the X-34 program, and found the existing processes in place at Orbital Sciences Corporation and its subs to be satisfactory. Recommendations from the review have been addressed, and are available for review. A follow-up review with Code Q and the X-34 Project Office was held on December 10, 1998.
Documents Related to Lesson:
N/A
Mission Directorate(s):
- Exploration Systems
- Aeronautics Research
Additional Key Phrase(s):
- Administration/Organization
- Aerospace Safety Advisory Panel
- Aircraft
- Computers
- Policy & Planning
- Risk Management/Assessment
- Software
- Spacecraft
- Test & Verification
Additional Info:
|
