REG NASA-LLIS-0393-1995 Lessons Learned - ATMOS Laser Failure.pdf

1、Lessons Learned Entry: 0393Lesson Info:a71 Lesson Number: 0393a71 Lesson Date: 1995-05-30a71 Submitting Organization: JPLa71 Submitted by: R.K. MallisSubject: ATMOS Laser Failure Abstract: A failure in the ATMOS instrument laser was attributed to a pressure loss caused by use of machine screws of ex

2、cessive length in a modified housing. Sealed flight equipment requiring container integrity should be designed to provide continuous passive indication of leaks. When modifying equipment, ascertain that the as-built configuration is understood.Description of Driving Event: After some two days of fli

3、ght aboard Spacelab 3, the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument failed when the laser did not turn on for occultation 75. The laser failed due to a high voltage arc-over, which resulted from a pressure loss in the laser housing. Investigation revealed that the pressure loss was

4、 caused by use of machine screws of excessive length. The housing had been modified, based on a Material Review Board decision, which resulted in threaded holes, which were of a different length than the original design drawings. Machine screws were used which matched the original design drawing but

5、 were too long when used in the as-built configuration, causing the integrity of the housing to be violated.Additional Keyword(s): Leak TestingLesson(s) Learned: 1. Failure to provide verification of seal integrity of pressurized containers can result in failure of flight equipment.2. All flight equ

6、ipment modifications require evaluation of resulting configuration changes.Recommendation(s): Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. Sealed flight equipment requiring container integrity should be designed to provide continuous passive in

7、dication of leaks by pressurizing above atmospheric pressure and monitoring with pressure transducers to provide evidence of proper pressure and seal integrity.2. When modifying equipment, care should be taken to ascertain that the as-built configuration is understood. Equipment can be modified by E

8、ngineering Change Notices or corrective actions based on Material Review Board decisions.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Configuration Managementa71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1986-09-11a71 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-,-,-