1、Lessons Learned Entry: 0368Lesson Info:a71 Lesson Number: 0368a71 Lesson Date: 1995-01-13a71 Submitting Organization: JPLa71 Submitted by: L. Dumas / G. CoyleSubject: Damage of Galileo Flight Antenna from Testing Abstract: Galileo: The spare Galileo high gain antenna was damaged during modal, acoust
2、ic, and pyro shock testing, resulting in the revocation of the flight qualification of the spare. Be cautious of informal environmental testing to validate analytical models; it is typically conducted without the strict test controls and unambiguous assignment of responsibility that are required for
3、 testing of flight subsystems and spacecraft.Description of Driving Event: The Galileo Spacecraft Development Test Model (DTM) included the spare flight antenna subsystem (SXA-1). Informal characterization testing used to validate the analytical model included extensive modal vibration testing. Seve
4、ral organizations were involved in both developing and conducting the tests.At the conclusion of three tests (modal, acoustic, and pyro shock), three problems were identified: 1) the surface mesh, restraining cords, certain fittings, and sunshade were damaged, 2) the number of vibration cycles permi
5、tted by Space Transportation System (STS) safety criteria had been exceeded, and 3) the antenna failed to deploy properly due to a cord snag.The first problem, which reduced RF output by 3.4 dB at X-band, was probably caused by fatigue-type wear during modal testing. The second problem was the resul
6、t of a calculation error during the test and would have precluded the use of the antenna for STS launch without some sort of refurbishment and requalification. The third problem, potentially mission catastrophic, was the third observed occurrence of a snag, indicating underlying design problems.The
7、project declared the SXA-1 antenna nonflight qualified due to gain loss, noncompliance with Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-STS criteria, and questionable deployment reliability.Lesson(s) Learned: Informal environmental testing to val
8、idate analytical models is typically conducted without the strict test controls and unambiguous assignment of responsibility that are required for testing of flight subsystems and spacecraft. The use of flight or flight spare hardware as aids in developmental testing can result in increased risk to
9、mission critical hardware.Recommendation(s): 1. The consequences and risk of damage to flight or developmental hardware imposed by test levels and test environment must be evaluated by the project office and the supporting technical division(s) with a formality commensurate with the consequences.2.
10、To clearly understand the results of environmental tests, especially those that include exploratory or characterization aspects, detailed physical and functional inspection should be performed between “separate tests“ to isolate any problems attributable to each particular test.3. The responsibility
11、 for the care and handling of any flight hardware should be unambiguously assigned throughout its preflight operational lifetime. Transfer of this responsibility should be unambiguous and formal.4. Kinematically indeterminate structures, not capable of detailed analysis, should be tested with protot
12、ype hardware rather than flight hardware.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Environmenta71 Hardwarea71 Test & VerificationProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Additional Info: Approval Info: a71 Approval Date: 1987-10-13a71 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-,-,-
