Conclusions The LLA shear tie design is capable of surviving wear due to ground test and launch with acceptable  wear patterns, which indicates positive life margin. After being subjected to an enveloping wear  environment during risk-reduction testing, shear tie specimens showed wear patterns indicative of early wear stages. Displacements during the test (with one exception, as noted in Table 4) were within 17% of  the desired value, and angular displacements were within 20% of the desired value. The reduction in measured displacements compared to “controlled” displacements occurred due to elastic compliance in the Instron machine and test fixture. The test levels were conservative to begin with (more than 2X predicted displacements), so it is considered that the test, as run, properly envelopes the wear expected  during ground test and launch. The wear levels observed on all three shear tie pairs were similar, which  indicates that the performance of the Tiodize/Tiolube 460 coating was consistent for the lot of parts that  were tested. Because between 0.3 and 0.5 degree of displacement was shown to occur with negligible  slip, any displacements that do occur during acoustic testing will have a negligible contribution to the overall wear of the shear ties. This demonstrates that the doubling of the number of 1-sigma cycles envelopes acoustic testing.  Test Telemetry The results of this test serve to indicate the importance of taking the correct telemetry during wear testing.  Good telemetry should isolate the measurement from test fixture deflections, providing a direct measurement of the desired data. By providing good telemetry, this test did more than just verify the wear life of the test specimens, it provided useful insights into the functioning of the shear tie interface that were used to verify assumptions about the wear environment, and determine the friction coefficient of the  coating under flight-like conditions. In addition, the contribution of test fixture displacement to the overall  displacement of the Instron machine was characterized.  Lessons Learned This test provided some key insights on testing wear surfaces. Analyzing test data in real time allows one  to catch issues that could compromise or invalidate test data and results. For example, a cursory examination of the test data between the one and two-sigma tests of the first shear tie pair caught the excessive test fixture slop early on in the test. The fact that test fixture displacement accounted for up to 20% of the desired rotation had little impact on the test result because of the high level of conservatism built into the test. If the level of conservatism had been lower, however, this could have been a significant problem. Test fixture displacements could have easily been characterized by examining data from the  phase 1 tests, and used to scale up the Instron displacement, which would have ensured that the desired  rocking angles were achieved. Acknowledgements  The authors would like to thank the following people for their contributions to this test: Ed Boesiger, Luke  Bunselmeyer, Stu Loewenthal, Mike Popyack, Kurien Thomas, Don Shaffer, and Charles Whipple.  170