1、Lessons Learned Entry: 1619Lesson Info:a71 Lesson Number: 1619a71 Lesson Date: 2005-08-08a71 Submitting Organization: JPLa71 Authored by: Ron Welcha71 POC Name: Ron Welch, David Oberhettinger, Richard Payntera71 POC Email: Ronald.T.Welchjpl.nasa.gova71 POC Phone: 818-354-7096Subject: Mate/Demate, Ve
2、rify, and Document Connectors One-at-a-Time (2003) Abstract: An integration and test failure was traced to an unmated flight connector that was registered as “mated” in the mate/demate log. The root cause was attributed to the failure of a technician/engineer to pause after each mate/ demate operati
3、on to enter it in the log, and to obtain QA verification. Flight connectors located in crowded or constrained areas (as well as those in more visible areas) must be mated or demated one-at-a-time under QA supervision, and accurate documentation of the connector status must be maintained. Description
4、 of Driving Event: When the navigation camera (Navcam) power was switched on during integration and test (I&T) of the Mars Exploration Rover (MER) spacecraft, voltage measurements showed no power or data signals within the Navcam circuits. The Navcam had worked properly when tested prior to an earli
5、er removal and re-installation of the Rover Power Distribution Unit (RPDU). An investigation revealed an un-mated connector on the Nonvolatile Memory and Camera Interface Board (NVMCAM) within the Rover Electronics Module (REM) (Figure 1). The assembly procedure called for the mating of this connect
6、or, and the mate/demate log indicated that the connector had been mated. The root cause of the workmanship error was attributed to the failure of a technician/ engineer to pause after each mate/demate operation to enter it in the log, and to obtain Quality Assurance (QA) verification. A high connect
7、or density and an obstructed view within the REM make it difficult to verify the status of a single connector once multiple connectors Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-have been mated. MER also has other high-density connection areas s
8、uch as the Rover bulkheads (Figure 2). Fig 1. The unmated connector was located beneath the flex cable shown in this photo of the REM, and the mating operation is conducted with the flex cable in place. Fig 2. Example of high density cabling and connections along the MER bulkheads.Although the impac
9、t of this error was minor, de-integration and rework to re-mate a connector in a highly integrated system like MER can pose a major risk to flight hardware. After this incident, the Assembly, Test, and Launch Operations (ATLO) manager mandated a “one at a time” practice of QA verification after ever
10、y MER connector mate/demate, and it did not permit mate/demate of multiple connectors prior to obtaining QA support. References:1. JPL Problem/Failure Report No. Z79107, January 20, 2003.2. “Crimping, Interconnecting Cables, Harnesses, and Wiring,” NASA-STD-8739.4, February 9, 1998. 3. “Magellan Bat
11、tery Fire,” LLIS No. 0386, NASA Lesson Learned Information System (LLIS), February 23, 1995. 4. “Mismate of Identical Connectors, ASTROS Project, 1988,” LLIS No.0431, NASA Lesson Learned Information System (LLIS), September 14, 1995. 5. “Electrical Connectors,” LLIS No.0444, NASA Lesson Learned Info
12、rmation System (LLIS), July 30, 1993. 6. “Electrical Connectors - Scout Program,” LLIS No.0470, NASA Lesson Learned Information System (LLIS), July 22, 1994. Additional Key Words: connector mating, connector demating, QA procedure, blind mateLesson(s) Learned: Because the correct mating and demating
13、 of flight connectors is critical in producing a safe and fully functional component, it is imperative that detailed procedures be followed and that verification and documentation occurs at the appropriate points in time. Multiple connectors located in crowded or constrained areas (as well as those
14、in more visible areas) should be mated one at a time and under the surveillance of Quality Assurance. Each mate or demate should be verified and appropriately Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-documented so that the correct status of th
15、e hardware is maintained at all times. Recommendation(s): Revise mate/demate requirements to ensure that flight connectors located in crowded or constrained areas (as well as those in more visible areas) are mated or demated one at a time and under the supervision of QA. Each mate or demate in these
16、 types of areas should be verified by QA and documented, one at a time, to ensure that the status of the component is maintained at all times. In extreme visibility problem areas, the technician mating/demating activities and QA oversight shall be simultaneous. Evidence of Recurrence Control Effecti
17、veness: Preventive Action Notice No. Z87343 was opened by JPL on August 23, 2005 to initiate and document appropriate Laboratory-wide action on the above recommendation. Documents Related to Lesson: a71 “Spacecraft Design & Fab Requirements (D-8208), Rev. 1,” JPL Requirement No. DocID 35120, January
18、 14, 2002. a71 “JPL Standard for Systems Safety (D-560),” JPL Requirement No. DocID: 34880, March 9, 1999, Para. 4.7.6. a71 “Quality Assurance Responsibilities for ATLO, Rev. C,” JPL Quality Assurance Procedure No. QAP 71.0, JPL DocID: 43332, November 19, 1999. a71 “Quality Assurance Training and Ce
19、rtification Program, Rev. 0,” JPL Quality Assurance Procedure No. QAP 21.0, JPL DocID: 63874, June 2, 2003. Mission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Aeronautics Researcha71 Space OperationsAdditional Key Phrase(s): a71 Flight Equipmenta71 Ground Equipmenta71 Hardwarea71 Human Fa
20、ctorsa71 Independent Verification and Validationa71 Industrial OperationsProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Payloadsa71 Safety & Mission Assurancea71 Test & Verificationa71 Test ArticleAdditional Info: a71 Year of Occurrence: 2003Approval Info: a71 Approval Date: 2006-11-30a71 Approval Name: ghendersona71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
