1、Lessons Learned Entry: 0396Lesson Info:a71 Lesson Number: 0396a71 Lesson Date: 1995-06-07a71 Submitting Organization: JPLa71 Submitted by: K. FlynnSubject: SIR-B Antenna Feed Anomaly Abstract: Shortly after transmitter turn-on, SIR-B suffered a radiated power drop. After Shuttle landing, troubleshoo
2、ting discovered a sliver of metal embedded in the center conductor of the GFE antenna cable. For critical GFE components, obtain copies of the test procedures and the test data; perform RF breakdown and end-to-end system tests.Description of Driving Event: The SIR-B Shuttle Mission 41-G exhibited a
3、SIR-B transmitter radiated power drop of 8-10 dB shortly after transmitter turn-on. A corresponding increase in the reverse power (as noted in the telemetry) and a drop in received echo amplitude were also noted. Troubleshooting performed at KSC after Shuttle landing revealed a low resistance path (
4、approximately 5 ohms) from the center conductor of the antenna cable to the coax shield. The cable assembly (AE9492) was part of the antenna system, which was provided as GFE by the Johnson Space Center who returned it to the manufacturer for failure analysis. The manufacturer found that a sliver of
5、 metal was embedded in the teflon dielectric of the connector.Lesson(s) Learned: 1. Review and verification of test procedures and test data from critical components supplied as GFE by other organizations ensures that project testing requirements have been met.2. RF breakdown tests on RF generation
6、or amplification and antenna feed system components provide assurance that the components meet flight operational requirements.3. End-to-end system tests are particularly critical if the system includes data generation and data flow.Provided by IHSNot for ResaleNo reproduction or networking permitte
7、d without license from IHS-,-,-Recommendation(s): 1. If critical components are manufactured and tested and supplied GFE by organizations other than the laboratory, the cognizant development organization should request copies of the test procedures and the data derived from these tests to determine
8、that the equipment meets the project testing requirements.2. RF breakdown tests should be conducted on all radio frequency generation or amplification and antenna feed system components that are susceptible to breakdown. Test plans should include sufficient system perspective to ensure that the test
9、s are conducted at power levels that demonstrate a margin over the flight power levels and for a period of time commensurate with the planned flight operating duration.3. End-to-end system tests should be conducted on large complicated systems to verify RF breakdown margins.Evidence of Recurrence Co
10、ntrol Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Safety & Mission Assurancea71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1986-10-13a71 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-,-,-
