The objective is In line with last ECSS working group meeting conclusions, the objective is to explore the effectiveness of reducing uncertainty margins to provide more competitive mechanisms without impacting their reliability. The activity will define the typeof parameters at mechanism level and at system level for which there are uncertainties of behaviour, that could be better known andevaluated such that more optimized and reduced uncertainty factor could be used under certain conditions and in relation with operator's feedback. This would increase the competitiveness of European products. The difficulties to understand the origin of failures mechanics of space mechanisms lead to systematically oversize the functional architecture with both uncertainty and motorization factors since these devices are usually single point failure. The development risks and recurring cost resulting from the objective of achieving compliance to these factors hampers the competitiveness of new products, thereby limiting the competition faced by incumbent technologies. Within telecommunication spacecraft business, often, the combination of price, mass and volume constraints in combination with ECSS margins leads to a less competitive mechanism design: either too big and/or too heavy and too costly, or with toolow performances. Telecommunication spacecraft often use flight proven mechanisms from the US, but in many cases these US based mechanisms do not fully comply with the ECSS uncertainty margins, especially at actuator level. This creates an unfair disadvantage to European mechanism manufacturers. Effectively, US mechanisms with flight heritage are allowed lower margins. This activity aims atbetter optimizing and assessing the impact of reduced uncertainty and thereby to optimise margins of flight proven European mechanisms, which would create a larger application range for these mechanisms, and thereby improve competitiveness. Justification: The identification of a process to optimise the functional design of flight-proven mechanisms used on telecommunication satellites would give European products a guideline towards increased market share. Work logic:Identify a flight proven recurring mechanism qualified for telecom mission with applicable and quantified functional margins. Based on the experience of the bidder (FMECA, ...), the finalcustomer requirements (operators), flight experience/monitoring and the bidders knowledge of the product, propose a test plan inorder to be able to justify the use of reduced uncertainty margins and assess evaluate the effects on future flight models in term ofcost, overall performance and reliability. The samples under test will be Engineering Models supported by preliminary breadboarding tests. Perform a test campaign in representative conditions and document the results. Based on the test, quantify the potential improvement in performance, mass, volume, and in cost. Identification of candidate mechanism(s) for further development Generate a guideline for optimising mechanism designs for public reference. For the up-to-date intended issue quarter/intended issue week information, please consult the telecom website: http://artes.esa.int/artes-51/tenders.