1、Lessons Learned Entry: 0273Lesson Info:a71 Lesson Number: 0273a71 Lesson Date: 1993-07-08a71 Submitting Organization: JPLa71 Submitted by: T. IskenderianSubject: TOPEX/POSEIDON Solar Array Drive (SAD) Drop Abstract: Two days prior to the planned delivery of the flight Solar Array Drive, the unit was
2、 accidentally dropped on the floor. An employee who was unfamiliar with the device tilted the assembly to take a measurement, unaware that the SAD was not fastened to the fixture. The recommendations center on training and procedures, examination of the fixtures before use, and QA involvement.Descri
3、ption of Driving Event: Two days prior to the planned delivery of the flight Solar Array Drive, the unit was accidentally dropped on the floor.Final dimensional inspection was being performed on the SAD at the contractors facility. The device was cradled in its drilling and alignment fixture, but in
4、 order to accommodate inspection, was not fastened down. There were no instructions to fasten the SAD to the fixture during manipulation, nor were any warnings posted to indicate that special caution was necessary during the inspection process. There were no documented requirements for quality assur
5、ance (QA) or other cognizant personnel to witness the inspection, and none were present. An employee who was unfamiliar with the device tilted the assembly to take a measurement, unaware that the SAD was not fastened to the fixture. The SAD tumbled out of the fixture, rolled across the surface plate
6、, and fell about 40 inches to the floor. Its housing was damaged in at least two areas, and there was concern that the output bearings had also been damaged by the impact.The SAD was disassembled to facilitate damage assessment, and extensive analysis, testing, and inspection were performed to deter
7、mine its flight worthiness. No evidence of bearing damage was noted, but repair of the damaged housing areas was required. The Material Review Board (MRB) agreed with the proposal to reassemble the SAD without replacement of any major components. Provided by IHSNot for ResaleNo reproduction or netwo
8、rking permitted without license from IHS-,-,-Following the reassembly and inspection, flight acceptance tests (including environmental tests) were successfully repeated.The incident resulted in a two month delay in the SAD delivery and considerable cost increase to the program. A major effort was re
9、quired by the review board and the JPL/Contractor SAD teams to assess, rework, and retest the SAD to assure its flight worthiness.Reference(s): PFR #55704, MRB 00036Lesson(s) Learned: 1. There is a potential for damage whenever flight hardware is handled, even for operations that may appear to be ve
10、ry routine.2. Utilization of existing fixtures for purposes other than as originally designed increases the risks involved in handling of flight hardware.3. When new personnel are brought onto a job, or duties are shared among existing personnel, hardware handling operations incur additional risks.R
11、ecommendation(s): 1. Employees should be familiarized with clear, safe handling practices and instructions written and agreed upon by both the NASA center and the contractor. These standards should be posted in work areas and enforced by quality assurance.2. Perform a careful examination and review
12、of potential risks prior to utilization of existing fixtures for additional handling operations.3. Quality assurance personnel should review and approve all fixturing and setups for flight hardware prior to use.4. Inexperienced personnel should be supported by experienced personnel for a time suffic
13、ient to assure that they have been adequately trained in handling of flight hardware and are thoroughly familiar with the hardware and associated procedures.5. Use special awareness in the development of handling procedures and techniques in the event that someone other than the originator may be re
14、quired to perform those functions.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Mission Directorate(s): N/AAdditional Key Phrase(s): a71 Policy & Planninga71 Risk Mana
15、gement/Assessmenta71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1992-09-24a71 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-,-,-
