REG NASA-LLIS-0632-1999 Lessons Learned Designs for in-flight mating of sealing surfaces.pdf

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1、Lessons Learned Entry: 0632Lesson Info:a71 Lesson Number: 0632a71 Lesson Date: 1999-07-20a71 Submitting Organization: ARCa71 Submitted by: Dave ZimmerSubject: Designs for in-flight mating of sealing surfaces Description of Driving Event: During the STS-90 flight, there was a repeated need to access

2、the specimens contained within the Animal Enclosure Modules. The operation to gain access required the mating of equipment and covers that had seals (and sealing surfaces) designed to contain contaminants and particulates. The attachment mechanism to hold these mating surfaces together were simple q

3、uarter turn fasteners designed to simplify attachment. In flight, it was discovered that the crew had a difficult time pressing the mating components together (to compress the seals) and engaging the fasteners at the same time.Lesson(s) Learned: In the microgravity environment it is difficult for cr

4、ew members to mate and attach sealing surfaces together unless the attachment mechanism assists the crew in applying a load to hold the surfaces together. Designs that help in this attachment include:1. Screw thread lids, where the screw thread can be started before the seal starts to compress.2. Ca

5、m-lock devices, where the mechanism can be positioned and engaged and then the cam mechanism assists in applying a force to compress the seal.3. The use of clamps, where the clamp can be positioned and engaged and then a screw thread can be utilized to supply the force to compress the seal and hold

6、the surfaces together.It should be noted that while screw threads are recommended to provide a mechanical advantage to help mate these surfaces, that friction alone (at the screw thread interface) should not be relied upon to hold the components together.Provided by IHSNot for ResaleNo reproduction

7、or networking permitted without license from IHS-,-,-Recommendation(s): See lesson(s) learned.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Aeronautics ResearchAdditional Key Phrase(s): a71 Flight Equipm

8、enta71 Hardwarea71 Payloadsa71 Research & Developmenta71 Safety & Mission Assurancea71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1999-08-02a71 Approval Name: Anthony Bricenoa71 Approval Organization: N244-30a71 Approval Phone Number: 415-604-1012Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-