History of Product  The product was developed and fully qualified in 1999 with two test units. The initial production run of 4  units was delivered, and successfully flown, with the FalconSatl program. Following the initial run,  roughly six production runs were completed for various programs, totaling roughly 50 units. During this  time, we became aware of improvement opportunities as we worked to support customers with specific  flight applications. These were primarily usability issues related to damage during handling and operation,  and included:  0 Cutoff switch arm breakage  0 Reset difficulty  0  0  0 Strain relief of lead-wires SMA wires burned by excess pulse energy  Mechanism damage due to bolt over-engagement  Some of these issues were addressed with engineering changes during these first 6 production runs. In  2004, engineering proposed more extensive design changes and an internal research and development  effort was initiated. Production of the original design (Gen 1) was to continue until the new design(s) (Gen  2 and 3) and the delta-qualification program was completed. There were two versions of the new design  to be qualified to suit different programmatic needs. The Gen 2 design did not include an in-line current  shut-off feature. The Gen 3 design included a redundant, in-line current shut-off rated for Flight use as  well as ground operation. While the above designs were being developed, the final planned production lot  of the Gen 1 design was in process (circa May 2004). During this time, we encountered a failure in  vibration testing of several Gen 1 Engineering units at levels well below qualification.  Test Failures  Four significant test failures have occurred during the product life to date. These failures occurred  sequentially and were linked together as the process of investigation and resolution were carried out for  each. As each of the failures was investigated, our understanding of the mechanism increased. In some  cases, the failures required an exhaustive process of properly addressing any and all affected hardware  in the field. As painful as it was, the investigation process created invaluable opportunities to roll  improvements into the Gen 2 and 3 designs, requiting in an extremely robust final product.  Starsys’ FRB (Failure Review Board) process involves a systematic approach to failure resolution,  utilizing tools such as failure trees, fishbone diagrams, and detailed tracking of closure actions. Regular  reporting of progress and senior technical oversight continue until root cause and corrective action plans  are determined, and the investigation is closed. From June of 2004 until November of 2005, the  QWKNUT was under nearly continuous FRB activity for each of the failures described. These failures are  an example of how a qualified design can fail, and evolve, over the product life-cycle.  Engineering Unit Vibration Failures  In June of 2004, an Engineering Unit QWKNUT (Gen 1) undergoing development vibration testing  released the nominal 13345-N (3000-lbf) preload under the relatively low ievel of 12 Grms compared to  the 35 Grms qualification level. In reviewing the test setup, there were a number of potential causes  including cross-axis noise on the vibration table, and a non-standard, massive bolt interface. However,  two more EDU units at Starsys Research were vibration tested and also showed an intermittent release of  preload at levels below the 35 Grms qualification. We initiated an FRB action to investigate the anomaly.  With roughly 38 Gen 1 flight units delivered to customers and staged for flight use, there was concern  regarding the scope of the anomaly and status of units in the field.  The engineering team generated a complete failure tree. As potential causes were eliminated, the failure  tree pointed to the latch release portion of the mechanism. High-speed video of the failure event showed  the lever arm moving slightly during vibration with respect to the toggles, and then moving suddenly, and  fully, in the direction of release. A cause for this behavior could not be found initially. Physical and  dimensional inspection of the parts did not reveal any clear discrepancies. The engineering analysis  77