1、Lessons Learned Entry: 0285Lesson Info:a71 Lesson Number: 0285a71 Lesson Date: 1993-08-06a71 Submitting Organization: JPLa71 Submitted by: H. T. EnmarkSubject: Wide Field/Planetary Camera II (WF/PC II) Charge Coupled Device (CCD) Failure Abstract: Although an alert had been issued on a thermal wire
2、stripper, its use during the WF/PC II CCD assembly process resulted in damage to the engineering model camera head.The alert process should be re-examined and consideration given to reissue of certain alerts on a periodic basis. Assembly involving flight components should be controlled by the approp
3、riate practices and procedures required for flight hardware. Description of Driving Event: The WF/PC II engineering model camera head did not image properly during initial power-on electrical tests. The malfunction was determined to be a failure of the CCD. After a new CCD was installed, the camera
4、head was again found to be inoperative due to the same type of CCD failure. It was determined that both failures were caused by the use of an ungrounded thermal wire stripper during the CCD assembly process. The strippers had a measured voltage of 32 volts AC on the tips, more than enough to damage
5、the CCDS.Investigation into the cause of the failures revealed that alerts had been issued some six years ago on this particular model of wire stripper.The devices that were destroyed in this event were two of only 28 remaining units in existence (one CCD is required for each of the 8 camera heads i
6、n the WF/PC II flight assembly). Obtaining additional devices would have extreme cost and schedule impact on the WF/PC II build.Additional Keyword(s): Electrostatic DischargeProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Reference(s):1. PFR #53937 a
7、nd #539342. JPL Quality Assurance Alert QAA 019 (9/14/84)3. Government-Industry Data Exchange Program Problem (GIDEP) Advisory H6-P-90-01 (no date)Lesson(s) Learned: 1. The current scope of distribution of alerts does not assure that people using similar equipment will be alerted, particularly if so
8、me time has elapsed.2. Use of any equipment with the potential of feeding electrical energy into sensitive electronic devices must be planned with great care to eliminate the risk of damage.Recommendation(s): 1. The alert process should be re-examined and consideration given to reissue of certain al
9、erts on a periodic basis.2. Assembly involving flight components, even in non-flight equipment such as engineering models, should be controlled by the appropriate practices and procedures required for flight hardware, including grounding of soldering tips and wire strippers.Evidence of Recurrence Co
10、ntrol Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Energya71 Parts Materials & Processesa71 Safety & Mission AssuranceAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 1991-08-09a71 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-,-,-
