REG NASA-LLIS-4059-2011 Lessons Learned - Flexhose Quick Disconnect (QD) Design Improvement for Easier Use.pdf

1、Public Lessons Learned Entry: 4059 Lesson Info: Lesson Number: 4059 Lesson Date: 2010-09-14 Submitting Organization: KSC Submitted by: Annette Pitt Subject: Flexhose Quick Disconnect (QD) Design Improvement for Easier Use Abstract: Large quick disconnects (QDs) in ground support equipment (GSE) can

2、be very difficult to successfully mate to air half couplings (AHCs) because they have bulky, heavy hoses that must be rotated along with the ground half couplings (GHCs) in order to be attached to the AHCs. It frequently takes several attempts to successfully mate the QDs. Often it appears that the

3、GHC is successfully mated to the AHC, only to find out later that the mate was not successful. The weight, orientation, and degree of twist of the hose relative to the QD make it difficult to lock the connection in place, even by pulling on the hose. It would be easier to mate the GSE to the vehicle

4、 if the design of the flexhose interposed a swivel mechanism between the hose and QD. The GHC could then be moved and rotated much more easily, thereby reducing the risk of having a failed mate. Description of Driving Event: The horizontal drain lines in the Shuttle Orbiter Power Reactant Storage an

5、d Distribution (PRSD) system are very long, very heavy flexhoses with a large diameter. Their quick disconnect (GHC) mates to the Orbiter PRSD system (AHC) on the outside of the Orbiter are used to drain PRSD tank commodities (GH2 and GO2) as part of the Orbiter postlanding operations. Because the h

6、ose must rotate with the fitting, it is very difficult to achieve a firm mate between the GHC and the AHC. It typically takes technicians an hour or more to accurately perform the operation. Furthermore, on occasion the mate appeared to be secure, but later inspection showed that the mate was not fi

7、rm. This could create a safety concern because, in the event that predrain leak checks were not performed properly, a failed mate could cause GH2 to be vented at the connection. Lesson(s) Learned: The operation could be performed more easily and successfully if a swivel mechanism were interposed bet

8、ween the end of the flexhose and the GHC. This would enable the GHC to be more easily rotated and twisted so that it could be mated with the AHC without the need to rotate and twist the remainder of the flexhose. This would save time and effort by making it easier to achieve a firm mate between the

9、GHC and AHC on the first attempt. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-View of Flexhose being mated to Shuttle Orbiter Air-Half-Coupling View of Air-Half Coupling Recommendation(s): Provided by IHSNot for ResaleNo reproduction or networkin

10、g permitted without license from IHS-,-,-Consider using a swivel mechanism in future flexhoses. Evidence of Recurrence Control Effectiveness: N/A Documents Related to Lesson: N/A Mission Directorate(s): Exploration Systems Space Operations Additional Key Phrase(s): Ground support systems Launch supp

11、ort systems Human Factors Quality Configuration Change Control Engineering design and project processes and standards Human factors planning Lander Systems Launch Systems Orbiting Vehicles Advanced planning of safety systems Ground processing and manifesting Additional Info: Project: Space Shuttle Program Approval Info: Approval Date: 2011-06-28 Approval Name: mbell Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-