REG NASA-LLIS-4416-2012 Critical System Maturity Requirements Critical System Analytic Model and Critical System Certification Proces.pdf

1、Public Lessons Learned Entry: 4416 Lesson Info: Lesson Number: 4416 Lesson Date: 2010-09-24 Submitting Organization: KSC Submitted by: John Hampton Subject: Critical System Maturity Requirements, Critical System Analytic Model, and Critical System Certification Process Abstract: It is important to e

2、stablish the environment in which equipment is to operate prior to designing or specifying it. Once the design or specification is set, NASA should not forego certification testing as this may give rise to continuing costs over the life of the program. Description of Driving Event: The Shuttle progr

3、ams original specification was that all flight hardware was to be rated to survive a 200k amp lightning strike. When it came to certification testing, the flight elements applied for and were granted waivers to these requirements. Its unclear whether they would have failed the certification testing

4、or it was too expensive to accomplish. No testing of any kind was done. Thereafter, during the major portion of the vehicles operational life, there were no fact based criteria for accessing the vehicles flight worthiness in the wake of a direct or nearby lightning strike.Columbia Accident Investiga

5、tion Board (CAIB) Report Lesson(s) Learned: It is obvious that skipping the qualification of the vehicle to in areas involving the natural environment will present reoccurring problems. In the case of failing to perform lightning certification, the potential to induce voltages and currents has resul

6、ted in many uncertain situations where each design center has to decide from the available evidence whether or not the vehicle is flight worthy. This has been time consuming and has resulted in un-necessary testing and discussions. Many times the decision had to be made using data that was lacking c

7、ompleteness or was inconclusive. Recommendation(s): When writing specifications, take into the account the environment that the equipment is to operate within and write sensible conservative specifications. Once the equipment is built, do not allow waivers to requirements that are derived from the n

8、atural environment. Evidence of Recurrence Control Effectiveness: N/A Documents Related to Lesson: N/A Mission Directorate(s): Space Operations Additional Key Phrase(s): Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Electromagnetic Environment Elec

9、tromagnetic Interference Technology Readiness Level Proprietary Technology Integration and Testing 1.Mission definition and planning 1.Planning of requirements verification processes 1.Level 0/1 Requirements 1.Program planning, development, and management 1.Crew Survival Systems Decision Support System Certification Process Operational Environment Additional Info: Project: Space Shuttle Program Approval Info: Approval Date: 2012-08-13 Approval Name: mbell Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-