REG NASA-LLIS-0465-1995 Lessons Learned - Crimped Electrical Connections - Scout Program.pdf

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1、Lessons Learned Entry: 0465Lesson Info:a71 Lesson Number: 0465a71 Lesson Date: 1995-06-13a71 Submitting Organization: LERCa71 Submitted by: Judy TerlepSubject: Crimped Electrical Connections - Scout Program Description of Driving Event: Functional failures were attributed to varying resistance value

2、s through crimped electrical connections (contacts, splices, terminals). The variation was from several milliohms to open circuits. Microscopic examination of the cross-section of the crimped area revealed either insufficient crimping or excessive deformation of the wire strands.Samples of the vario

3、us combinations of crimp connections (connector pins, connector sockets, terminal lugs, or splices) and wire gauges were made using various crimp tools and settings. Cross-sectioning of these samples indicated that the manufacturers recommended settings and positioners did not always provide the bes

4、t crimp conditions. Pull test results on similar crimp connections correlated with the cross-section conclusions.In 1975 the Scout Program established its own crimping standard, which specified the crimp tool model, contact positioner, and setting (if applicable) for each connection type (manufactur

5、er and part number), single or double leads, and stranded wire gauge. Crimping on solid buss wire was not considered acceptable. All applicable personnel were trained and certified on crimping and assembling contacts on connectors.Each day a specific crimp tool (serial number, model) was used, two s

6、amples of the specific anticipated combination (contact part number, wire gauge(s) were made and each sample was subjected to a pull test. Both samples had to meet the established pull test requirements, which were based on the wire gauge capability. After meeting the pull test, the production hardw

7、are contacts were crimped. If a sample failed, then the tool was rejected per established procedures.Similar crimp contact controls have been imposed on applicable vendors and subcontractors.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Lesson(s) L

8、earned: Manufacturers Recommendations for crimped connector settings are not always correct and can result in inadequate crimp conditions.Recommendation(s): Perform frequent periodic sample pull tests on crimped connections.Evidence of Recurrence Control Effectiveness: Improved requirements signific

9、antly reduced the problem of unstable circuit resistance through crimped electrical connections.Documents Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Hardwarea71 Parts Materials & ProcessesAdditional Info: Approval Info: a71 Approval Date: 1996-10-25a71 Approval Name: Sell Jamesa71 Approval Organization: 501-4a71 Approval Phone Number: 216-433-8618Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-