REG NASA-LLIS-1711-2005 Lessons Learned - Deep Impact Reiterates the Need for Peer Review and Contractor Oversight (2005).pdf
《REG NASA-LLIS-1711-2005 Lessons Learned - Deep Impact Reiterates the Need for Peer Review and Contractor Oversight (2005).pdf》由会员分享,可在线阅读,更多相关《REG NASA-LLIS-1711-2005 Lessons Learned - Deep Impact Reiterates the Need for Peer Review and Contractor Oversight (2005).pdf(4页珍藏版)》请在麦多课文档分享上搜索。
1、Lessons Learned Entry: 1711Lesson Info:a71 Lesson Number: 1711a71 Lesson Date: 2005-08-29a71 Submitting Organization: JPLa71 Submitted by: Carol Dumaina71 POC Name: Doug Clark, Dan Karmona71 POC Email: Douglas.J.Clarkjpl.nasa.gova71 POC Phone: 818-354-3427Subject: Deep Impact Reiterates the Need for
2、 Peer Review and Contractor Oversight (2005) Abstract: The over-current detection scheme for Deep Impact spacecraft heater circuitry failed to detect an over-current condition during ground test due to an inadequate circuit design and test design. The root cause was inadequate contractor oversight a
3、nd peer review. The lessons learned from the MCO mission loss on the value of detailed technical review and contractor oversight must be re-emphasized, and test configurations should be subjected to FMEA and feature positive controls limiting electrical current.Description of Driving Event: During a
4、 test by a contractor on the heater circuitry in a Thermal Interface Board (TIB) for the Deep Impact Impactor, a ground support equipment (GSE) switch stuck in the closed position. This caused an opto-isolated field effect transistor (FET) switch (Figure 1) to fail in the ON condition (Reference (1)
5、. The TIB controls the heaters for the spacecraft panels, NiH battery, and thrusters, and it is located in the Remote Interface Unit (RIU), an assembly (Figure 2) responsible for engineering telemetry collection and remote subsystem control. Provided by IHSNot for ResaleNo reproduction or networking
6、 permitted without license from IHS-,-,-Figure 1, a color photograph of an FET die appears as a perforated, rectangular, metallic plate withFigure 1. Destructive physical analysis showed electrical overstress damage (indicated by arrow) to the Deep Impact TIB FET die. Figure 2 is a color photo of a
7、laboratory area, where a technician is bent over a partially assembleFigure 2. Installation of the flight Remote Interface Unit (RIU) on the Deep Impact Impactor spacecraft. The GSE switch was a momentary switch mounted on a GSE test box. Its purpose was to short the output of the FET switch to grou
8、nd to verify that the heater over-current detection circuitry and the field programmable gate array (FPGA) could detect a short and shut off the heater. A defect in the GSE switch is suspected to have caused repeated cycles of intermittent contact that kept the input voltage above the over-current s
9、ense voltage level that would have caused the FPGA to trigger a shutdown of the FET switch. In-flight failure or unintentional turn-off of an FET switch (optocoupler) in the TIB controlling the heaters could cause severe under-temperature conditions with catastrophic results. Both the TIB over-curre
10、nt detection circuit and the test configuration were poorly designed by a subcontractor to the JPL system contractor. There was very limited oversight by JPL, with an average of less than one JPL engineers time assigned to monitoring development and test of the Command & Data Handling Subsystem. In
- 1.请仔细阅读文档,确保文档完整性,对于不预览、不比对内容而直接下载带来的问题本站不予受理。
- 2.下载的文档,不会出现我们的网址水印。
- 3、该文档所得收入(下载+内容+预览)归上传者、原创作者;如果您是本文档原作者,请点此认领!既往收益都归您。
下载文档到电脑,查找使用更方便
10000 积分 0人已下载
下载 | 加入VIP,交流精品资源 |
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- REGNASALLIS17112005LESSONSLEARNEDDEEPIMPACTREITERATESTHENEEDFORPEERREVIEWANDCONTRACTOROVERSIGHT2005PDF

链接地址:http://www.mydoc123.com/p-1019253.html