REG NASA-LLIS-0303--1993 Lessons Learned Galileo Spin Bearing Lubricant Problem.pdf

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1、Lessons Learned Entry: 0303Lesson Info:a71 Lesson Number: 0303a71 Lesson Date: 1993-09-15a71 Submitting Organization: JPLa71 Submitted by: J. LangmaierSubject: Galileo Spin Bearing Lubricant Problem Abstract: Although, the synthetic lubricant on Galileo slip ring bearings had been replaced with KG80

2、 oil, the porous, phenolic ball retainer had absorbed some of the previous lubricant. Under vacuum, this residual synthetic lubricant reacted with the KG80 to form a black goo. When cleaning spaceflight components, the cleaning process must be followed by an outgassing vacuum-bake treatment- particu

3、larly for porous materialsDescription of Driving Event: The Galileo flight control slip ring test fixture bearings had once been lubricated with a synthetic lubricant. This was eventually replaced with KG80 oil to simulate actual Spin Bearing Assembly (SBA) operating conditions in space. After appro

4、ximately 3 months of life testing (under vacuum) at 3 RPM, the bearing lubricant had a thick, black, gooey appearance and the bearing friction torque was higher than expected. It was discovered that even with careful cleaning prior to the test, some of the original synthetic lubricant remained in th

5、e porous, phenolic ball retainer. Under vacuum, this residual synthetic lubricant migrated to the surface, reacting with the KG80 to form the black gooey material. A new bearing with a nonporous steel ball retainer was installed.Lesson(s) Learned: Even careful cleaning of spaceflight components can

6、leave residues which may eventually react with adjacent materials.Recommendation(s): When cleaning spaceflight components, the cleaning process must be followed by an outgassing Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-vacuum-bake treatment. T

7、his is particularly important for porous materials which may have absorbed various fluids, including the cleaning medium itself.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Hardwarea71 Parts Materials & Processesa71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 1986-06-25a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-