REG NASA-LLIS-0431-1996 Lessons Learned Mismate of Identical Connectors ASTROS Project 1988 (Repeated Events a Galileo b TOPEX c Cassini).pdf

1、Lessons Learned Entry: 0431Lesson Info:a71 Lesson Number: 0431a71 Lesson Date: 1996-07-15a71 Submitting Organization: JPLa71 Submitted by: J.W. BottSubject: Mismate of Identical Connectors, ASTROS Project, 1988 (Repeated Events: a. Galileo b. TOPEX c. Cassini) Abstract: During the system assembly pr

2、ocess for the ASTROS Tracker, two external interconnect cables between the Sensor Assembly and the Electronic Assembly were cross connected. This problem was repeated on the TOPEX project and in two instances on Cassini: one transposition of connectors made it necessary to remove and replace 26 over

3、 stressed transistors. Lesson #0431 provides 6 recommendations regarding connector configuration, installation, placement, identification, and inspection.Description of Driving Event: During the system assembly process of the S/N 002 ASTROS Tracker, two external interconnect cables between the Senso

4、r Assembly (SA) and the Electronic Assembly (EA) were cross connected.*Causes of the problem:1. At the EA end of the cable harness, the design incorporated the use of identical connectors.2. On the EA, mating connectors were installed side by side.3. Identification of connectors on the cables was in

5、adequate, and not readily apparent.4. Inadequate attention was paid to positioning of the connectors during the installation process. Fortunately, the ASTROS Instrument suffered no damage as a result.Repeated Events: a. On the Galileo Project, a Data Memory System flight unit was severely damaged wh

6、en two internal cable connectors were transposed. Identical connectors, installed side by side, were Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-cross connected under poor conditions for recognition. In this case, it was necessary to remove and r

7、eplace twenty-six over stressed transistors.b. On the TOPEX Project, a similar event occurred at the Satellite System Contractor. Unfortunately, details of that problem are no longer readily available. Due to the nature of the circuitry involved, the effects of the transposition of connectors was re

8、latively minor.c. On the Cassini Project, a similar event occurred at a supplier facility. Two test cables were reversed during set-up. The unit did not experience any additional stresses as a result.*Additional Keyword(s): Assembly Practices, CablingReference(s): *PFR #41718 & *PFR #59732Lesson(s)

9、Learned: Inadequate connector identification and/or adjacent placement of identical connectors when combined with human error can result in mismating of interconnect cables, with potentially damaging effects.Recommendation(s): 1. Avoid placing identical connectors in adjacent locations where mating

10、connectors can easily be transposed during installation.2. When the conditions noted in recommendation #1 above are unavoidable, add a requirement that all connectors to be mated are clearly identified by color codes or other means which will make it obvious if transposition is about to occur during

11、 the mating process.3. If feasible, configure the cables in such a manner that the cable connectors cannot readily be mated with the wrong connector.4. Ensure that assembly technicians are trained, and sensitized to the dangers inherent in the transposition of connectors.5. Mandate that any mate of

12、identical paired connectors be verified by a second party (preferably Quality Assurance) before any application of power.6. Series connect unique pairs of jumpered pins in identical connectors, and terminate the series connection in an external connector. Verify installation by continuity test.Evide

13、nce of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Mission Directorate(s): N/AAdditional Key Phrase(s): a71 Configuration Managementa71 Flight Equipmenta71 HardwareAdditional Info: Approval Info: a71 Approval Date: 1995-09-14a71 Approval Name: Carol Dumaina71 Approval Organization: JPLa71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-