1、Public Lessons Learned Entry: 6256 Lesson Info: Lesson Number: 6256 Lesson Date: 2011-11-28 Submitting Organization: GSFC Submitted by: Jerome Kosko Subject: Procedure Devolvement over Time in a Seriesed Spacecraft Program Abstract: National Oceanic and Atmospheric Administration (NOAA) N-Prime is o
2、ne of a series of satellites built by the Goddard Space Flight Center (GSFC) and uses handling procedures originally developed at the programs outset. The spacecraft has a deploy-able Search and Rescue Antenna (SRA) which was originally “hard stowed” using a non-flight bolt and T-nut in the baseline
3、d procedure. The procedure was progressively modified and devolved over time due to the changing GSE availability and allowed for using a lance cord in lieu of the hard stow to secure the antenna in a “soft stow”. During ground operations the spacecraft was rotated and the SRA inadvertently deployed
4、 when the cord broke. The SRA broke through a hard stop bracket and damaged an instrument optical sensor radiator panel. The satellite damage was minimal and there were no injuries to personnel. A Mishap Investigation Board (MIB) was commissioned to investigate this mishap. Their findings form the b
5、asis for this lesson. Description of Driving Event: The NOAA-N Prime Search and Rescue Antenna (SRA) inadvertently deployed during a spacecraft rotation on April 14, 2007. This rotation was part of a normal operation to configure the spacecraft for additional antenna and the solar array boom deploym
6、ents. A Turn Over Cart (TOC) is used to re-orient the spacecraft from vertical to horizontal, and allows for the axial rotation of the spacecraft when in the horizontal position. This axial rotation is sometimes referred to as a “rotisserie” motion. An Operational Hazards Assessment (OHA) and Functi
7、onal Failure Modes and Effects Analysis (FFMEA) were performed for this TOC, but that analysis is primarily focused on the design and load carrying capability of the fixture, without a broad assessment of various possible spacecraft configurations. The historical Integration and Test (I no analysis
8、of the cord strength when the new procedure was implemented; the tie procedure is non-specific and will not result in a consistent tie performance; no specific requirement of which lacing cord to use (3 sizes were available for use); instructions of how to tie the lacing cord are vague and technicia
9、n access is limited; and, a Functional Failure Modes and Effects Analysis (FFMEA) was not performed for the satellite in this configuration (using a lacing cord tie restraint system for the SRA) and subjected to this operation (horizontal rotisserie). The lesson learned for this mishap is directly d
10、erived from its root cause as stated by the Mishap Investigation Board: Root Cause - Lack of due diligence, inadequate Engineering/Management practices which led to a vague procedure. Over time the baseline procedure was modified to accommodate the changing operational environment and devolved into
11、one that was no longer adequate yet was accepted simply because it worked. There was no overarching surveillance in place which may have precluded the flawed procedure from being used or at least evaluated to assess its current validity. Recommendation(s): Whenever serial or continuous procedures ar
12、e repeatedly used they should include a provision to periodically review them against their baseline versions. Where possible, the assumptions of the baseline procedure that conceivably could lead to future risk should be included with the procedure. The intent is to avoid a practice that worked fro
13、m becoming the new standard without any particular analysis of the new configuration of use. When the operational environments or process applications change a review of procedural assumptions should be conducted to look for application specific assumptions that may not be valid in the new use confi
14、guration. Evidence of Recurrence Control Effectiveness: N/A Documents Related to Lesson: N/A Mission Directorate(s): Space Operations Additional Key Phrase(s): Integration and Testing Mission Operations and Ground Support Systems.Crew Operations Mission Operations and Ground Support Systems.Ground p
15、rocessing and manifesting Mission Operations and Ground Support Systems.Ground support systems Additional Info: Project: NOAA Approval Info: Approval Date: 2012-02-03 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Name: mbell Approval Organization: HQ Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
