1、Lessons Learned Entry: 1216Lesson Info:a71 Lesson Number: 1216a71 Lesson Date: 1999-04-21a71 Submitting Organization: JSCa71 Submitted by: Roger Striegel/ Ronald A. MontagueSubject: Use of “Pathfinder“ Strategy to identify configuration process anomalies Description of Driving Event: The initial run
2、s of an On-Orbit Constraint Test (OOCT) at KSC ran into a number of anomalies. These initial runs were the first attempts (or “pathfinder“ event) in a series of OOCT from which lessons learned would result in smoother, more efficient OOCTs prior to future flights. The OOCT are a series of tests that
3、 emulate one side of an element to element interface using test aids. These Test Aids are set up in a test configuration with the flight element to be tested. The flight crew actually comes to KSC to conduct the test on the flight hardware. The OOCT is considered training for the crew as well as a c
4、heckout of the on-orbit procedure with the actual flight hardware.Both Extra-vehicular Activities (EVA) and the Inter-vehicular Activities (IVA) are subject to the OOCT discipline. In an OOCT, connect cables, fluid ducts and umbilicals on the flight are run in a test configuration so that routing, m
5、ating/de-mating of the flight hardware, clocking, length of lines, stress/strain or twisting of cables and potential obstructions to be encountered can be evaluated.This pathfinder OOCT occurred for Flight 3A where Node 1 was emulated (Node 1 is on-orbit) and with PMA3 (Flight 3A) which had been del
6、ivered (DD250) to NASA. The PMA3 configuration actually encountered during the test set-up was different than envisioned from review of the drawing package from which the test aid alignment data and test procedure had been generated. The test procedures are generated from the on-orbit operational se
7、quences being built by mission planners (in this case, in JSCs Missions Operations Directorate, or MOD).Because of the misunderstandings documented in the root causes below, the test alignments, setup of the test aids and the actual conduct of the tests exceeded the planned test timeline. While the
8、test was completed successfully, a regression test will have to be conducted to repeat parts of the test because of insufficient / incorrect data available for the test procedure.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Root causes: 1. Setup a
9、nd Alignment Data for the Test Aid was insufficient, incorrect and misunderstood by the KSC support teams responsible for the test aid setup and alignment of the test configuration. There was no tabletop review of this data with KSC prior to these pre-test activities nor was the data formally releas
10、ed prior to pretest activities.2. The On-Orbit Constraints Meeting was not utilized as a requirements gate review. Since this was the initial test, this meeting was process oriented and lacked specific implementation requirements to be agreed to and baselined.3. Hardware fit interference - overhangi
11、ng of PMA3 by EVA test aid - was not anticipated. It was a surprise to the test team. With appropriate configuration control processes, this would not have occurred. Scaffolding and protective padding was applied to the element.4. Undocumented mating targets were applied to mating / sealing surfaces
12、 because target locations identified were not on same planar surface as expected. Because the test technicians had done similar exercises before, the targets were applied successfully prior to test.5. N2 and O2 lines were incorrectly called out in the test procedure. Test Procedure was written to th
13、e PMA3 to Node3 ICD that is the correct data source. This was questioned prior to TRR and PMA3 Flight Element team provides a sketch of the lines which was also incorrect. The running of the test identified several errors including this one.Lesson(s) Learned: When faced with first-time performance o
14、f complex tests and operations, consider using “pathfinder“ disciplines to perform process shakedowns to identify loopholes and escapes.Recommendation(s): 1. Test Aid Configuration Control2. a) Identify a KSC Test Conductor with knowledge of the flight hardware. b) Conduct tabletop reviews of all te
15、st aid requirements and test procedure documentation with KSC personnel prior to release. c) Structure test procedures so that all crew conducted steps are congregated in one section for efficient accomplishment. Identify specifically on the test timeline and at the crew test pre-brief. d) Release a
16、ll test aid requirements documents and test procedures prior to TRR. e) Add test aid to flight element configuration drawing as an Appendix to the Test Aid Requirements Document. f) Schedule all reviews and document releases on the element schedules at KSC 2. Use of existing management forumsa) Crea
17、te a checklist of success criteria for the On-Orbit Constraints Meeting. Add checklist to the Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-agenda for all On-Orbit Constraints Meetings. b) Add obstruction dimension and mounting requirements for the
18、 OOCT to the Test Aid Requirements Document (TARD) for release. c) Add test aid setup and alignment requirements data to the TARD as an Appendix for release. 3. Integrated configuration controla) Add general warning to the test procedures on protecting flight hardware when overhangs occur. b) Develo
19、p a footprint of the test configuration for all tests. c) Add performance of CAD model assessment of the test configurations to identify potential flight hardware safety concerns. d) Add a test configuration assessment of the On-Orbit Constraints meeting and a review of the assessment at the Test Re
20、adiness Review. 4. Congency planning for discrepancies to reduce downstream impactsa) Add element and system hardware representatives to the mandatory review of test requirements and test procedure documents. b) Add all subsystem hardware providers to the Test Readiness Review. c) Call out specifica
21、lly in the test procedure all locations for the application of targets and the procedure by which they are to be applied. d) Include the element managers from both the hardware provider and the program integrator are at the TRR. Reschedule the TRR if necessary to insure proper attendance. 5. Resolvi
22、ng data conflictsa) All data conflicts should be identified as Test Constraints and identified with resolution at the TRR. Only formal engineering paper should be considered sufficient documentation of resolution and closure not sketches. b) Add all Test Constraints to the TRR agenda as a specific t
23、opic. This will act as a second review gate of all issues prior to the start of test. Evidence of Recurrence Control Effectiveness: Action taken at Houston: This lesson is one that was entered by the Test & Verification team. As a result of our earlier efforts in performing fit checks and on-orbit c
24、onstraints test, we learned some valuable lessons. Everyone of the listed recommendations has been implemented and are currently in place. The ISS Boeing Physical Interface Verification Manager was brought in to add discipline and experience to this effort. As a result of his leadership, the process
25、 has turned the corner. The results of these lessons have been captured in a program instruction for this effort and this approach has been approved by the ISS Test & Verification Control Panel.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Document
26、s Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Administration/Organizationa71 Configuration Managementa71 Disposala71 External Relationsa71 Extra-Vehicular Activitya71 Facilitiesa71 Flight Eq
27、uipmenta71 Flight Operationsa71 Ground Equipmenta71 Ground Operationsa71 Hardwarea71 Independent Verification and Validationa71 Industrial Operationsa71 Information Technology/Systemsa71 Lifting Devicesa71 Parts Materials & Processesa71 Payloadsa71 Policy & Planninga71 Procurement Small Business & I
28、ndustrial Relationsa71 Range Operationsa71 Risk Management/Assessmenta71 Safety & Mission Assurancea71 Softwarea71 Spacecrafta71 Test & Verificationa71 Test Articlea71 Test FacilityAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2002-06-17a71 Approval Name: Ronald A. Montaguea71 Approval Organization: JSCa71 Approval Phone Number: 281-483-8576Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
