1、Public Lessons Learned Entry: 5479 Lesson Info: Lesson Number: 5479 Lesson Date: 2010-10-1 Submitting Organization: KSC Submitted by: Annette Pitt Subject: Proper Manufacturing, Handling, Use, Storage and Care Of Metal Bellows Flex Hoses Abstract: Metal bellows flex hoses are very susceptible to rev
2、erse bending low cycle fatigue which results in leakage via a through crack in the bellows. Description of Driving Event: In the late 1980s early 1990s time frame there were multiple failures of convoluted metal bellows flex hoses used in various shuttle orbiter systems. Some of these systems were c
3、ritical to launch, mission success and to the health and safety of the crew. Fortunately the failures occurred and were detected during ground processing and the discrepant hoses were replaced before flight. The video below discusses this situation. Click here to view a transcipt of the video Lesson
4、(s) Learned: Figure 1: View looking down OV-102 Hoses Flt 27 Figure 2:OV-104 Flex Hose Deformation Besides the normal certification testing criteria for what is classically considered failure modes for passive system elements, the effects of manufacturing defects, improper cleaning and drying, stora
5、ge, handling, operational use and collateral damage should also be taken into account when determining their in service maintenance requirements and life. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Also when using metal bellows flex hoses in an
6、application where the hose extends and retracts it is important to ensure that the minimum bend radius is not exceeded and that there is no induced reverse bending occurring during the entire travel of the hose. It is very difficult if not impossible to detect, by inspection, impending reverse bendi
7、ng fatigue failure of the metal bellows convolutes that occurs due to storage, handling, operational use ( hoses that are routinely disconnected and connected ) and incidental collateral damage. Recommendation(s): When incorporating metal bellows flex hoses into a system design ( ground support equi
8、pment or flight ) it is important to test the hoses before each use on the ground or in flight if it is difficult to determine how much reverse bending flexure the hose is being subjected to. It is also important to have a more rigorous inspection program for these hoses and to provide protection fo
9、r the hoses during ground processing whenever possible. Cost should also be factored in for a more frequent replacement interval for the hoses to avoid failures especially in critical or hazardous systems. Evidence of Recurrence Control Effectiveness: N/A Documents Related to Lesson: KNPR 8715.3 KSC
10、 Safety Practices Procedural Requirements NSTS 07700, Volume XI Revision B Space Shuttle System Payload Accommodations Click here to download STS-114 OPF Rollout Review document Click here to download Flexhose Failure Analysis Report Mission Directorate(s): Space Operations Exploration Systems Addit
11、ional Key Phrase(s): 1.Test & Verification 1.Quality 1.Maintenance 1.Early requirements and standards definition 1.Lunar Operations 1.Logistics and maintenance 1.Launch support systems 1.Ground Operations 1.Planetary entry and landing concepts 1.Human factors planning 0.Environmental Control and Lif
12、e Support Systems 1.Ground processing and manifesting 1.Ground Equipment 1.Facilities 1.Cryogenic Systems 1.Computer-Aided Design/Manufacturing/Engineering 1.Aircraft 1.Reliability 1.Ground support systems 1.Safety & Mission Assurance 1.Risk Management/Assessment 1.Pressure Vessels 1.Parts, Material
13、s, & Processes 1.Packaging, Handling, Storage Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1.Logistics 1.Launch Vehicle 1.Industrial Operations 1.Hardware 1.Spacecraft Additional Info: Project: Space Shuttle Program Approval Info: Approval Date: 2011-11-03 Approval Name: mbell Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
