1、Lessons Learned Entry: 0389Lesson Info:a71 Lesson Number: 0389a71 Lesson Date: 1995-03-13a71 Submitting Organization: JPLa71 Submitted by: Jim TaylorSubject: In-Flight Power Converter Failure Abstract: During a switch between Voyager radio receivers, a failure occurred due to a short circuit traced
2、to a screw contacting components insufficiently coated by the solithane conformal coating. Designers should be aware of tolerance build-up in assemblies and assure that there is adequate margin.Description of Driving Event: This event involved both Voyager radio receivers. The failure occurred when
3、a flight operations software command loss routine switched the S/C configuration from Receiver 1 to Receiver 2. Receiver 1 had operated normally from launch until the inadvertent switch to Receiver 2 and subsequent controlled switch back to Receiver 1. The Receiver 1 power converter failed 11 second
4、s after the switch back. Other subsystem telemetry was also noted to be anomalous during this short time. Receiver 2 on first use after the inadvertent switch was discovered to have a shorted loop capacitor and thus unable to lock to normal uplink. After the Receiver 1 failure, the spacecraft switch
5、ed Receiver 2 on. Receiver 2 has subsequently continued to support the mission. Its use required special Deep Space Network (DSN) uplink acquisition tuning procedures and periodic in-flight receiver best lock frequency checks to compensate for the failed loop capacitor. The analysis indicates that t
6、he short circuit within Receiver 1 was screws. The metal particle contacted components insufficiently coated by the solithane conformal coating.Lesson(s) Learned: Build-up of design tolerances in assemblies can result in in-flight equipment failure.Recommendation(s): Provided by IHSNot for ResaleNo
7、reproduction or networking permitted without license from IHS-,-,-Designers should be aware of tolerance build-up in assemblies and assure that there is adequate margin.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 1985-12-19a71 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-,-,-
