REG NASA-LLIS-2896-2010 Lessons Learned - GOX Vent Hood Failsafe Jackscrew.pdf

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1、Public Lessons Learned Entry: 2896 Lesson Info: Lesson Number: 2896 Lesson Date: 2010-05-21 Submitting Organization: KSC Submitted by: Annette Pitt Subject: GOX Vent Hood Failsafe Jackscrew Abstract: On the Space Shuttle launch tower, the swing arms that raise the gaseous oxygen (GOX) vent hood inco

2、rporate a jackscrew assembly. An addition to a commercial off-the-shelf (COTS) jackscrew assembly was designed and implemented. The failure of one of the jackscrews used to raise and lower the GOX vent hood was traced to wear of the drive nut threads. Close inspection of moving equipment should be p

3、erformed on a regular basis, regardless of the lack of published criteria. Description of Driving Event: The failure of one of the jackscrews used to raise and lower the gaseous oxygen (GOX) vent hood was traced to wear of the drive nut threads. This wear caused the threads to strip under use and al

4、lowed the hood to fall to its lowered position during raising operations. The cause of the wear was traced to the keyed shaft, coupled with a bend in the shaft itself that allowed the keyway to function as a lathe and remove a portion of the threads with each traverse of the shaft through the drive

5、nut. The wear of the drive nut or the straightness of the shaft were not checked regularly, and there were no instructions to do so. The use of a keyed shaft also added to the accelerated wear observed. Lesson(s) Learned: Close inspection of moving equipment should be performed on a regular basis re

6、gardless of the lack of published criteria. Recommendation(s): Keep abreast of community updates to the maintenance recommendations for similar items and incorporate changes to maintenance procedures as required. Watch for modifications that increase the safety and operability of equipment. Evidence

7、 of Recurrence Control Effectiveness: There have been no failures caused by wearout since implementing the increased maintenance. The secondary drive nut has never engaged. Documents Related to Lesson: GOX Vent Hood Jackscrew drawing document Click here to download communication document. Mission Di

8、rectorate(s): Exploration Systems Space Operations Additional Key Phrase(s): 1.Lifting Devices 1.Ground Equipment 1.Long term sustainability and maintenance planning 0.Entry Systems Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- 1.Ground support sy

9、stems 1.Administration/Organization 1.Reliability 1.Maintenance 1.Logistics and maintenance 1.Launch support systems 1.Hardware 1.Ground Operations Additional Info: Project: Space Shuttle Program Approval Info: Approval Date: 2010-07-13 Approval Name: mbell Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-