1、Lessons Learned Entry: 1222Lesson Info:a71 Lesson Number: 1222a71 Lesson Date: 1998-09-30a71 Submitting Organization: JSCa71 Submitted by: John P. Badalich Jr./ Ronald A. MontagueSubject: Understanding specific operational characteristics of selected design options (threaded Inserts) Description of
2、Driving Event: Galling of threaded fasteners was experienced in the qualification test program of the Z1 Truss. Fasteners intended to be removable on-orbit galled during test. The fasteners were installed in locking threaded inserts (“KEEN“ type).Root cause: The inherent effect of the “Keen“-type, u
3、pset thread design is to bite hard into the fastener. After repeated installation and removal, the fastener will gall. These inserts work best engaged once, and are excellent in this application.Lesson(s) Learned: A full understanding of the intent of a design is mandatory to ensure that operational
4、 requirements can be metRecommendation(s): If threaded inserts of this type must be used, “condition“ the insert first with a sacrificial bolt of the same type. The sacrificial bolt will cold work the upset thread slightly to help mitigate the probability of galling during repeated use. Lab analysis
5、 of this cold working procedure was performed; results are available from the lesson initiator. Evidence of Recurrence Control Effectiveness: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Documents Related to Lesson: N/AMission Directorate(s): N
6、/AAdditional Key Phrase(s): a71 Parts Materials & Processesa71 Procurement Small Business & Industrial Relationsa71 Risk Management/Assessmenta71 Test & Verificationa71 Test ArticleAdditional Info: Approval Info: a71 Approval Date: 2002-06-27a71 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-,-,-
