2016-07-282016-07-282016-07-10ICES_2016_251http://hdl.handle.net/2346/67624ItalyNetherlandsThales Alenia Space ItaliaAltranESA206ICES206: Manned Orbiting Infrastructures, Space Station and Payload Thermal ControlVienna, AustriaG. Bufano, Thales Alenia Space, ItalyA. Itta, Thales Alenia Space, ItalyR. Bianchi, Thales Alenia Space, ItalyG. Truscelli, Thales Alenia Space, ItalyJan Persson, European Space Agency, The NetherlandsStephan Hinderer, European Space Agency, The NetherlandsThis paper describes the flux of on orbit and on ground investigations that have involved the WPA Mk I, from the issue detection to the identification of the subsystem involved, until the detailed investigation of the causes and the WPA refurbishment and re-acceptance. The WPA Mk I was replaced with the spare unit in July 2013, then downloaded and successfully refurbished. The on orbit investigation demonstrated that the hydraulic section had worked properly and that the issue had occurred on the electric section. The ground investigation was composed of two parts, which could not be performed on orbit since the WPA Mk I was a unique ORU, differently from the Mk II that is composed of different ORUs. The first was a series of tests, programmed in such a way to identify whether it had occurred in the motor or in the electronic box: the result was to localize the failure in the electric box. The second was a set of dedicated electrical tests to track down the location of the issue: the result was to identify the failed board. This complex activity required to accurately plan the sequence and the type of tests in order to be able to unambiguously identify the problem. Since no spare units are available for the time being, a re-acceptance campaign of the downloaded and repaired unit is necessary. The re-acceptance campaign is ongoing and once it will be completed the re-accepted unit will be uploaded if necessary. In the meantime the WPA Mk II is undergoing the qualification campaign and when ready it will be launched to replace the current unit. The issue that has been detected on the Mk I is not expected on the Mk II, because on the latter the electronic box is based on a different, more innovative technology.application/pdfengPumpWPATroubleshootingRefurbishmentPresentation