MSG SCAN DRIVE UNIT – FM5 LESSONS LEARNT

摘要

The Scan Drive Unit (SDU) is a linear actuatorrndeveloped as a subassembly of the SEVIRI ( SpinningrnEnhanced Visible and Infrared Imager) for Meteosatrnsecond generation program.rnThe qualification of the mechanism was performed endrnof 1999 with a delivery of 3 flight models. In 2004, arn4th flight model (FM4) initially ordered as a sparernmodel, has been acceptance tested and provided for thernMSG-4 mission. Despite the successful completion ofrnacceptance tests at unit level and performance tests atrninstrument level, an anomaly occurred at satellite levelrnafter acoustic environment survey.rnIn 2008, the decision was taken to manufacture a newrnflight model (FM5). For stock, cost and planningrnreasons, the agreed baseline was to re-use to thernmaximum extend, after proper refurbishment, the keyrnmechanical parts/components from the Engineeringrnmodel (EM), like housing, stepper motor, roller screwrnand ball bearings. Only in case of available attritionrn(e.g. potentiometer, bellows), or in case of non-hirelrnparts (internal harness) or less complex parts,rnreplacement by new parts has been considered.rnThis article aims to present :rn1. the way Thales Alenia Space Cannes hasrnproceeded to prevent any risks during thernassembly process, to guaranty the goodness ofrnthe old sub-assembly parts from EM or fromrnattrition and to ensure the correctrnmanufacturing of the new elements,rn2. the difficulties encountered during integrationrnand testing,rn3. the lessons learnt linked to the remanufacturingrnof a complex mechanism afterrna long period of inactivity (manufacturingrnstand by).