1、Lessons Learned Entry: 1376Lesson Info:a71 Lesson Number: 1376a71 Lesson Date: 2003-01-06a71 Submitting Organization: JPLa71 Submitted by: David OberhettingerSubject: Certify Environmental Test Equipment and Facilities, and Qualify Operators (2002) Abstract: During thermal ambient testing of Mars Ex
2、ploration Rover (MER), condensation formed inside the test chamber and upon the flight article due to inadequate sealing and improper purging of the chamber during test. Flight avionics circuit boards were damaged. Require (1) periodic certification of all environmental chambers that can be used for
3、 environmental testing of critical hardware, and (2) periodic training and certification of all operators.Description of Driving Event: During thermal ambient testing of Mars Exploration Rover (MER) Rover Electronics Module (REM) (Reference (1), condensation formed inside the test chamber and upon t
4、he flight article. This test consisted of a 2-hour 25 deg C soak with a dry nitrogen purge rate of 2 SCFM, then a ramp to -55 deg C (with a rate of 2 deg/min), and a final soak at -55 deg C for 2 hours. Once the chamber temperature reached -55 deg C, frost (ice crystals) was observed on the cables i
5、nside the chamber. After the final 2-hour soak, the frost had thickened and the area inside the chamber pass-through was also frosted over. The condensation is the likely cause of damage that was observed on the flight avionics backplane after the REM boards were removed and inspected following the
6、test. The cause appears to be inadequate sealing and improper purging of the chamber during test. References (2), (3), and (4) report similar chamber control problems at JPL during this time period. The Jet Propulsion Laboratorys primary thermal-vacuum test chambers for use on flight equipment are o
7、perated with oversight by the JPL Environmental Test Laboratory (ETL) organization. However, as many as 50 pressurized and non-pressurized thermal chambers used chiefly for experiments, hardware development, and special purposes are maintained by various JPL laboratories. Although these facilities w
8、ere sometimes used to test flight and other critical hardware, many (including the chamber in question) were not certified by the ETL. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-References 1. Jet Propulsion Laboratory (JPL) Problem/Failure Repor
9、t No. Z77001, August 1, 2002.2. Jet Propulsion Laboratory (JPL) Problem/Failure Report No. Z76596, July 2, 2002.3. Jet Propulsion Laboratory (JPL) Problem/Failure Report No. Z77229, August 22, 2002.4. Jet Propulsion Laboratory (JPL) Problem/Failure Report No. Z78119, October 30, 2002.5. Lessons Lear
10、ned No. 0622, Use of Obsolescent Test Facilities Pose Risk to Hardware, May 24, 19996. Jet Propulsion Laboratory (JPL) Corrective Action Notice No. Z77321, August 29, 2002.Additional Key Words: test-induced failure, test damage, facility certification Lesson(s) Learned: A Centers environmental test
11、organization, such as JPLs ETL, should maintain a broad expertise in safely testing flight and other critical hardware in non-ambient environments. Operators of test chambers/equipment, including those outside the ETL facility, should be specifically trained for safe environmental testing practices,
12、 and the equipment should be reviewed and certified by the ETL.Recommendation(s): 1. Identify, and require periodic certification of, all environmental chambers capable of being used for environmental testing of flight and other critical hardware.2. 3. Require periodic training and certification of
13、all operators in the correct operation of environmental chambers for safe testing of flight and other critical hardware.Evidence of Recurrence Control Effectiveness: Corrective Action Notice No. Z77321 was closed by JPL on November 7, 2003. The measure taken to implement Laboratory-wide corrective a
14、ction on the above recommendations was establishing a requirement that all chambers be certified and all operators be trained and certified, completing the training program, and documenting the operator training.Documents Related to Lesson: NPG 8831.2D, Facilities Maintenance ManagementMission Direc
15、torate(s): a71 Exploration Systemsa71 ScienceProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Cryogenic Systemsa71 Environmenta71 Facilitiesa71 Flight Equipmenta71 Ground Equipm
16、enta71 Ground Operationsa71 Hardwarea71 Payloadsa71 Policy & Planninga71 Risk Management/Assessmenta71 Safety & Mission Assurancea71 Spacecrafta71 Test & Verificationa71 Test Articlea71 Test FacilityAdditional Info: Approval Info: a71 Approval Date: 2004-02-09a71 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-,-,-
