Browsing by Author "Hinderer, Stephan"
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Item Analysis of Ammonia Moderate Leakage in Columbus(45th International Conference on Environmental Systems, 2015-07-12) Parodi, Paola; Locantore, Ilaria; Palo, Savino De; Szigetvari, Zoltan; Hinderer, StephanThis paper describes the analysis prepared to define the inputs for a timely detection and response to an ammonia moderate leakage from ISS Thermal Control System (TCS) into the Columbus module TCS water loop. Ammonia leakage is currently classified into three levels, with two extremes: the micro-leak, detectable generally via sample/strip analysis methods, the rupture, with a visible (FDIR reaction) flow of ammonia into the water loop, and the intermediate moderate leakage, visible via telemetry. At the time being, neither a moderate leak Flight Rule (FR) nor a dedicated malfunction procedure is available in Columbus’ books, therefore no guidance is provided to the flight team if a leak of that size develops. The advantage of implementing a moderate leakage response is that it covers the ‘gray zone’ between micro-leak and rupture, thus avoiding every leakage greater than the micro-leak to be treated as rupture, with the risk of over-reacting and stopping the activities inside the module when it is not the case.Item COLUMBUS Coolant Fluid Servicer – CCFS – Development and Implementation(46th International Conference on Environmental Systems, 2016-07-10) Szigetvari, Zoltan; Hinderer, Stephan; Bufano, GaetanaThe Columbus water cooling loop is of primary importance for proper thermal conditioning and operation of the module subsystem equipment as well as of the scientific payloads. Special care is taken to hydraulically insert and connect equipment or payloads to the Active Thermal Control System (ATCS) water loop which is free of air/gas to avoid the insertion of non-dissolved gases into the loop. The latter, if it happens, might cause cavitation or even damage to the Water Pump Unit (WPU) bearings. Until recently the Hydrocyclone unit had to be inserted into the Columbus water loop to remove the free air from the coolant water. Operation of this equipment was rather crew time consuming hence, an alternative approach had been requested by the European Space Agency (ESA) to be designed and built. Result of the investigations for alternatives revealed a membrane based degassing concept which has been developed, built and verified to fulfil the degassing as well as the water sampling maintenance activities within the ATCS. The following paper provides an overview of the former Columbus Hydrocyclone as well as the development, test, manufacturing, integration and operation of the “new” membrane based coolant fluid servicer.Item WPA Mk I: On orbit and on ground investigations and refurbishment activities(46th International Conference on Environmental Systems, 2016-07-10) Bufano, Gaetana; Truscelli, Gianni; Itta, Antonietta; Bianchi, Renato; Persson, Jan; Hinderer, StephanThis 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.