scope:

Abstract:

During STS-119 ground processing, a functional test of the Remote Manipulator System (RMS) was performed in accordance with OMI V1175, RMS Turnaround Verification, to ensure that all RMS hardware was ready for flight. The RMS shoulder brace was cycled and left in the latched position for flight. The required visual inspection for quality verification was reported as nominal. During the on-orbit checkout, the shoulder brace was released for operation. It was during this release that the crew reported a quicker than expected release (2 seconds instead of 5 to 8 seconds). Troubleshooting revealed that the requirements used to verify the shoulder brace latch prior to flight were not as accurate as thought. Historically, console program VAB40 was used to provide the data for the shoulder pitch angle prior to latching the shoulder brace. The requirement for shoulder pitch angle was 0.0 ± 0.1 degrees in order to latch. Troubleshooting revealed that the pitch angle must be 0.0 ± 0.07 degrees in order for the shoulder brace collet to engage. VAB40 only provided a resolution of one decimal place. Orbiter Display Page SPEC 169 provides a higher resolution of two decimal places and will be used for all future shoulder brace latch verifications. Lesson Learned: Ensure that the requirements can be supported by the actual testing and that the required resolution can be obtained from the specified data points.