1、Lessons Learned Entry: 0569Lesson Info:a71 Lesson Number: 0569a71 Lesson Date: 1997-10-09a71 Submitting Organization: JPLa71 Submitted by: D. OberhettingerSubject: Interface Control and Verification Abstract: Problems occurred during Mars Pathfinder spacecraft integration and test due to out-of-date
2、 or incomplete interface documentation. The problem of communicating design details and changes across interfaces is a common industry problem.Employ a dedicated ICD engineer, ensure proper notification of interface changes, and avoid maintaining separate in-house and vendor ICDs. Description of Dri
3、ving Event: The Mars Pathfinder (MPF) project operated under cost and schedule constraints. It employed new approaches for interface definition and control which produced both good and bad results.a71 In simplifying the expensive serial engineering change request (ECR) process, a dedicated JPL inter
4、face control drawing (ICD) coordinator was responsible for change control and for assuring that interface changes were approved by cognizant engineers. In addition, the Project Engineering Team met weekly to review all changes.Problems occurred during MPF spacecraft integration and test, however, du
5、e to out-of-date or incomplete interface documentation: a71 Electrical connector discrepancies were found between the MPF main wiring harness (delivered in July 1995) and 7 connectors on circuit boards in the Attitude and Information Management (AIM) subsystem. Investigation showed that the main wir
6、ing harness was built in accordance with MICDs which had not been updated after interfacing circuit board connectors were changed. This resulted in a connector mismatch-non-mating male-to-male Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-and femal
7、e-to-female connections. No power subsystem cabling was involved, and the discrepancies were corrected by retrofitting the cabling, or in some cases the boards, before any damage had occurred.a71 For some hardware items, it was discovered that JPL and vendors had each prepared MICDs independently.Ad
8、ditional Keyword(s): Electrical Interface Control Drawing (EICD), Mechanical Interface Control Drawing (MICD)Reference(s):a71 Muirhead, B., Mars Pathfinder Lessons Learned Presentations, April 17, 1997.a71 Mars Pathfinder Problem Log, IR 043306.a71 Mars Pathfinder ATLO Data Packagea71 JPL Common Thr
9、eads Workshop Summary Report, JPL D-13776, May 31, 1996.Lesson(s) Learned: 1. The problem of communicating design details and changes across interfaces-mechanical, electrical, and informational-is a pervasive common thread across JPL projects and throughout industry.2. Assignment of full responsibil
10、ity for interface control coordination to a single engineer, in conjunction with weekly Project Engineering Team reviews, results in an acceptable and cost effective engineering change control process.3. Mechanical Interface Control Drawings (MICDs) at all levels require periodic verification of acc
11、uracy and compatability, especially prior to any hardware fabrication.Recommendation(s): 1. Employ a dedicated engineer to assure that the hardware being built matches the ICDs.2. Ensure that cognizant engineers verify consistancy between their hardware and the MICDs/ assembly drawings, and provide
12、proper notification of interface changes.3. Use vendor ICDs where applicable, but do not maintain two sets.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Mission Direct
13、orate(s): N/AAdditional Key Phrase(s): N/AAdditional Info: Approval Info: a71 Approval Date: 1997-10-16a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
