This paper discusses some key factors which may arise for successful application of model-based Fault Detection(FD) techniques to aircraft systems.The paper reports on the results and the lessons learned during flight V&V(Validation &Verification) activities, implementation in the A380 Flight Control Computer(FCC) and A380 flight tests at Airbus(Toulouse, France).The paper does not focus on new theoretical materials, but rather on a number of practical design considerations to provide viable technological solutions and mechanization schemes. The selected case studies are taken from past and on-going research actions between Airbus and the University of Bordeaux (France). One of the presented solutions has received final certification on new generation Airbus A350 aircraft and is flying (first commercial flight: January 15,2015)