1、Lessons Learned Entry: 0428Lesson Info:a71 Lesson Number: 0428a71 Lesson Date: 1996-07-12a71 Submitting Organization: JPLa71 Submitted by: J.A. RobertsSubject: Electroexplosive Device Degradation with Time (1975) Abstract: In selecting squibs stored from the Viking Orbiter 1975 program for use in th
2、e Voyager 1977 mission, it was found that moisture sealed within the squibs at the time of manufacture had combined with the boron ignition mix to produce boric acid and corrosion. The manufacture of hermetically sealed squibs must preclude the presence of moisture prior to hermetic sealing. Flight
3、quality squibs in bonded storage must receive periodic resistance checks to detect degradation.Description of Driving Event: (Relevant Historical Lesson(s) Learned)Flight qualified electroexplosive devices (squibs) stored from the Viking Orbiter 1975 program were selected for use in the Voyager 1977
4、 mission. A twenty-eight day temperature soak resulted in increased bridgewire resistance for six of the ten samples. This was considered to be indicative of an incipient failure, the possible opening of the bridgewire with subsequent failure to fire upon command.Dissection of the squib which showed
5、 the greatest resistance increase revealed corrosion along the top of the bridgewire. None of the Voyager 1977 squibs built to the same specifications by the same manufacturer exhibited this resistance increase in similar testing. The phenomenon was attributed to moisture sealed within the squibs at
6、 time of manufacture, which combined with the Boron ignition mix to produce boric acid. Slow corrosion probably occurred with the passage of time. Selected squibs with no bridgewire resistance change were flown on Voyager.Additional Keyword(s): Contamination, PyrotechnicProvided by IHSNot for Resale
7、No reproduction or networking permitted without license from IHS-,-,-Reference(s): Voyager PFR 37909Lesson(s) Learned: The manufacture of hermetically sealed squibs must preclude the presence of moisture prior to hermetic sealing.Recommendation(s): Flight quality squibs in bonded storage must receiv
8、e periodic resistance checks to catch any degradation as it may occur. This is especially critical if squibs are inherited from past projects.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Environmenta71 Energ
9、etic Materials - Explosive/Propellant/Pyrotechnica71 Packaging Handling Storagea71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 1996-03-21a71 Approval Name: Carol Dumaina71 Approval Organization: JPLa71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
