1、Lessons Learned Entry: 0426Lesson Info:a71 Lesson Number: 0426a71 Lesson Date: 1996-07-12a71 Submitting Organization: JPLa71 Submitted by: J.A. RobertsSubject: Surveyor Rocket Motor Almost Fired (1965) Abstract: To prove that electrical connections were properly made, a test of motor control circuit
2、s was included after fueling and pressurization of tanks. Had slightly higher pressure been present in the fuel tanks when the pilot valve for the motor control was activated, rocket firing could have injured observers and destroyed the spacecraft. Functional tests must be carefully screened against
3、 a standing policy that at least two protective elements are included to prevent irreversible action.Description of Driving Event: (Relevant Historical Lesson(s) Learned)To prove that electrical connections were properly made, a test of motor control circuits was included after fueling and pressuriz
4、ation of tanks. Commands were issued and executed which “clicked“ the solenoid pilot valve for Surveyor motor control.Subsequent analysis exposed the fact that the motors could have fired if slightly higher pressure had been present in the fuel tanks. The test observer listening for clicks could hav
5、e been badly burned and the spacecraft destroyed.Additional Keyword(s): Safety, Hazardous Test, Redudant Protective ElementsLesson(s) Learned: Functional tests must be carefully screened against a standing policy that at least two protective elements are included to prevent irreversible action.Provi
6、ded by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Recommendation(s): Exceptions to including at least two protective elements should be even more carefully reviewed, and generally not allowed.Evidence of Recurrence Control Effectiveness: N/ADocuments Relate
7、d to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Safety & Mission Assurancea71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1996-04-25a71 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-,-,-
