1、Lessons Learned Entry: 0462Lesson Info:a71 Lesson Number: 0462a71 Lesson Date: 1994-07-25a71 Submitting Organization: LERCa71 Submitted by: Maria HavenhillSubject: Motor/Igniter Shelf Life - Scout Program Description of Driving Event: Motor information was routinely tabulated during the manufacture
2、of solid rocket motors. This information was furnished by the motor vendor (or obtained by resident representatives) from in-process propellant mechanical and ballistic properties testing. Typical properties included stress, strain, density, liquid-strand burn rate, propellant burn rate from subscal
3、e motor testing, and peel strength. Once logbooks were available, other parameters were tabulated. Typical properties were motor assembly total weight, propellant weight, case weight, linear weight, insulation weight, igniter propellant weight, igniter assembly weight, and nozzle assembly weight.Pos
4、t-flight motor performance information was tabulated for all flights (some fourth stage motors were not instrumented). Information items included thrust and chamber pressure. From these items were calculated Isp, total impulse, web burnout time, total burn time, and the pressure integral.Beginning i
5、n 1984, age related information was accumulated for the solid rocket motors to aid in engineering evaluation of motor shelf life. Typical information accumulated from storage site inspections, return-to vendor inspections, or launch site receiving inspections which included propellant shore a hardne
6、ss, radial slot width measurements, and visual inspections of the propellant grain surface and bond lines.As a result of the evaluation of motor shelf life, the Scout Program has been launching vehicles with motors that are well beyond the shelf life established by the motor manufacturer. Motor prod
7、uction to replace aging motors is costly. Use of the tabulated age related information allowed engineering and quality/reliability personnel to extend motor shelf life. New production was not required. Inventory motors could be flown.Further information can also be obtained by contacting the Reliabi
8、lity and Quality Division of Loral Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Vought Systems at P.O. Box 650003, Dallas, TX 75265-0003 or calling (214) 603-1000.Lesson(s) Learned: Vehicles with solid rocket motors older than the shelf life recom
9、mended by manufacturers can be launched.Recommendation(s): 1. Maintain extensive files related to rocket motor components weight, age, in-process testing, ballistic performance, and inspection.2. Update and analyze for effects on motor structural and ballistic performance.Evidence of Recurrence Cont
10、rol Effectiveness: The maintenance of extensive data files related to rocket motor information resulted in cost savings during motor production, a higher reliability of pre-flight motor performance predictions, and use of older motors.Documents Related to Lesson: N/AMission Directorate(s): N/AAdditi
11、onal Key Phrase(s): a71 Energetic Materials - Explosive/Propellant/Pyrotechnica71 Parts Materials & ProcessesAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 1996-10-25a71 Approval Name: Sell Jamesa71 Approval Organization: 501-4a71 Approval Phone Number: 216-433-8618Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
