1、Lessons Learned Entry: 1288Lesson Info:a71 Lesson Number: 1288a71 Lesson Date: 2002-01-01a71 Submitting Organization: ARCa71 Submitted by: DR Mendoza/ M. SumichSubject: Cost/schedule Optimization and Risk Reduction by Developing Two Independent Fully Functional Flight Vehicles with Limited Redundanc
2、y Description of Driving Event: In order to minimize cost and schedule, the project, after a trade-off analysis, decided to build two fully functional test vehicles as opposed to one with built in redundancy (note: those items deemed critical to safe operation were redundant). The test vehicles were
3、 of identical design but manufactured in sequence. Thus, while test vehicle number one was being flight tested, test vehicle number two was being built. The primary drivers for this approach were that the test vehicle was to be unmanned, have an emergency recovery parachute, and be operated in a ver
4、y controlled and unpopulated area. The risk of losing one vehicle was minimized by the imposition of these stringent test flight constraints. While it was the projects intention to complete the second vehicle as if it were the first and only, its main purpose was for risk reduction (the projects suc
5、cess meant vehicle number two was tested through ground taxi only). The second vehicle was also viewed as a source of parts for vehicle number one.Lesson(s) Learned: The approach to risk reduction mentioned above is credited with contributing significantly to the projects success, specifically:a71 H
6、aving two complete systems allowed the project to take an aggressive approach with respect to ground tests and flight envelope expansion.a71 Upper management approval and support was increased and maintained.a71 Lessons learned from developing vehicle number one could be applied to number two.a71 Th
7、e overall project milestones could be protected/met by using vehicle number two for spare parts.a71 The decrease in individual vehicle complexity over that of one with built in redundancy Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-decreased main
8、tenance requirements. Additionally, the approach mentioned above introduced several concerns:a71 Producing two complete systems spread the workforce very thinly, especially when resources between the two efforts were shared and/or had overlapping schedules.a71 Project management in general has a ten
9、dency to place all the best people on the team dedicated to the primary vehicle, such that the team working on the secondary vehicle suffers from inexperience and does not have the luxury of adequate mentoring/traininga71 The focus on vehicle number one, especially after it entered the flight testin
10、g phase, at times caused a loss of commitment to vehicle number two and jeopardized its schedule.a71 Risk management and safety efforts must always be supported and incorporated into project planning and should not be de-emphasized because there is a complete backup system. Recommendation(s): When u
11、sing unmanned flight vehicles in remote unpopulated areas, consider using a cost/schedule optimization and risk reduction approach based on developing two fully functional test vehicles instead of one with extensive sub-system redundancy. This approach should be accompanied with a dedicated effort t
12、o treat each vehicle as if it were unique and required to serve at any given time. Thus, the secondary vehicle should only be used as a resource to support vehicle number one after other risk mitigation strategies have failed. Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Les
13、son: N/AMission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Configuration ManagementProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Flight Equipmenta71 Flight Operationsa71 Risk Management/AssessmentAdditional Info: Approval Info: a71 Approval Date: 2002-10-09a71 Approval Name: Anthony Bricenoa71 Approval Organization: ARCa71 Approval Phone Number: 650-605-1012Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
