1、Lessons Learned Entry: 0354Lesson Info:a71 Lesson Number: 0354a71 Lesson Date: 1994-12-09a71 Submitting Organization: JPLa71 Submitted by: R.F. CollinsSubject: ATMOS Hygroscopic Optics Degradation Abstract: The ATMOS instrument suffered damage to its optical system as a result of excess humidity due
2、 to a climate control failure. Provide indicators and alarms for environmentally sensitive hardware, and ensure that adequate safeguards are in place.Description of Driving Event: On May 25, 1983, the ATMOS instrument suffered damage to its optical system as a result of a temporary outage of the spe
3、cial environmental control system due to a failure of the freon compressor. This environmental control system was necessary to meet the stringent humidity requirements of ATMOS while in the Spacecraft Assembly Facility (SAF). The failure caused the temperature in the ATMOS room to rise quickly to 77
4、 degrees F. and the humidity to 66%, a condition which damages the unprotected potassium bromide optics.The design constraint for the ATMOS humidity control is to remain below 40% relative humidity. The loss of control of temperature and humidity were caused by failure modes inherent in the humidity
5、 control system design, which were not adequately evaluated. When the failure occurred, no alarm was sounded as no sensors with alarms had been incorporated into the environmental control system.Lesson(s) Learned: Failure of environmental control systems, especially when no fail-safe alarms have bee
6、n incorporated into the system, can result in significant degradation of environmentally sensitive flight hardware.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Recommendation(s): 1. Environmentally sensitive hardware must be protected with indicat
7、ors and alarms from loss or degradation of the environmental control system. Safeguards must also include a method for alerting appropriate personnel in the event of a failure of the environmental control system. If the alerting system does not provide for adequate time for recovery action, redundan
8、t systems should be considered.2. A review of the environmental control system design and implementation by user and facility cognizant personnel should be performed to assure that appropriate safeguards are in place and that they are adequate for the level of protection required. System failure mod
9、es should be exercised to check out the safeguards and train the appropriate personnel.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Environmenta71 Test FacilityAdditional Info: Approval Info: a71 Approval Date: 1985-12-02a71 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-,-,-
