REG NASA-LLIS-2917-2010 Lessons Learned The Benefit of Individual Wire Identification in Space Flight Harnesses.pdf

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1、Public Lessons Learned Entry: 2917 Lesson Info: Lesson Number: 2917 Lesson Date: 2010-05-13 Submitting Organization: KSC Submitted by: Annette Pitt Subject: The Benefit of Individual Wire Identification in Space Flight Harnesses Abstract: The ARES I-X did not apply individual wire harness identifica

2、tion sleeves on the electrical wiring. Wire IDs were used in the Space Shuttle Program and were an important part of the Orbiter processing. The wire IDs aided in wire repairs, functional retest, and system fault isolation. The schedule impacts of not installing wire IDs were evident in the ARES I-X

3、 Program. Future Space Flight Programs should use wire identification as part of their wire harness fabrication process, or the initial build installation and ground flight processing will be impacted. Description of Driving Event: Flight processing time could have been reduced if individual wire id

4、entification sleeves had been applied to each wire. The use of wire identifications (IDs) would have helped in the following areas. 1. Wire Damage: Damage to wiring occurred during wire harness installation or as the result of collateral damage from work being performed in the area. ARES I-X had lon

5、g wire harness runs; therefore, the primary method to address wire damage was to repair in place because of the time and manpower required for wire replacement. The repair option was hindered by not having wire IDs. Wire repairs in some cases were intrusive and required electrical checkout post repa

6、ir (continuity, isolation, hipot testing, and functional retest). The wire function would have to be determined and required one of the following: a. Trace the wire to a downline connector. The wire harnesses were helicoiled and made tracing the wire to a connector termination point. b. Continuity c

7、hecks to determine the function of a damaged wire. Multiple connectors would have to be demated for this check and in some cases this invalidated previous functional flight tests or required access to areas already closed out for flight. This method could result in impacts to ground processing miles

8、tones. 2. Connector Rework: The wire harnesses were fabricated in accordance with engineering drawings but there were many cases where the wires were improperly pinned by errors in the design drawings. Wire IDs would have aided in the repining process. 3. Wire Safing: A damaged wire that had the pot

9、ential to short to ground or another wire would result in vehicle power down until the wire function could be determined. The wire short could result in damage to flight electrical components. This resulted in an impact to ground testing to electrically safe the damaged wire. Lesson(s) Learned: Wire

10、 IDs were used in the Space Shuttle Program and were an important part of the Orbiter processing. The wire IDs aided in wire repairs, functional retest, and system fault isolation. The schedule impacts of not installing wire IDs were evident in the ARES I-X Program. Future Space Flight Programs shou

11、ld use wire identification as part of their wire harness fabrication process, or the initial build installation and ground flight processing will be impacted. One example of the value of wire harness IDs in the Shuttle Program is the ability to determine the wire function using only the wire ID. A w

12、orst-case scenario is wire damage detected during final closeouts, and when post repair requires a functional retest. If the function is unknown, there are two ways to resolve this condition: perform extensive hardware removals to isolate the wire function or perform functional retest of all wires i

13、n the harness. A complete functional retest of all the wires in the harness may not be possible if it contains functions that cannot be retested in the vertical configuration. In this case, it would cause flight hardware removals to isolate the function. The removal of flight hardware in final close

14、outs would likely drive a slip in the planned launch date. Depending on the vehicle design, this issue could result in the de-stack of the vehicle. The Orbiter has experienced many cases of wire damage just prior to flight, and wire IDs were invaluable in resolving the issues quickly without impacti

15、ng the planned launch date. Recommendation(s): Individual wire identification should be used on space flight vehicles. Evidence of Recurrence Control Effectiveness: N/A Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Documents Related to Lesson: N/A

16、Mission Directorate(s): Exploration Systems Space Operations Additional Key Phrase(s): 1.Engineering design and project processes and standards 1.Acquisition / procurement strategy and planning 1.Ground processing and manifesting Additional Info: Project: Space Shuttle, ARES I-X Approval Info: Approval Date: 2010-07-29 Approval Name: mbell Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-