A lot depends on what you want to do with it. If you have a first degree in an aeronautical subject a Masters may not give you a whole lot extra. Bear in mind some of the course fees notably the City one are quite steep.
If you are in the industry already you might like to consider Kingston which offers an MSc as a mixture of taught and practical modules.
Aircraft Engineering PgDip/MSc - Postgraduate courses - Kingston University London
In the field of maintenance very little credit seems to be given, by the CAA or the practitioners, to holders of academic degrees, believing that the hands-on ex-shopfloor route is the only one worth doing (perhaps because the CAA and the practitioners tend to have taken that route themselves).