A degree in aircraft maintenance won't add much to your overall skills.
If you want to get a degree as a "banker" for moving outside the industry or which will be useful when moving up into management, rather than staying with a specialist degree in aircraft maintenance, I'd recommend studying for a more general management degree such as a BSc in Economics.
In addition to compulsory modules that cover the important business areas such as management accounting (bean counting), corporate finance, human resources, industrial psychology etc., you can add interesting options such as politics (Machiavelli is especially valuable) and end up being able to play the bean-counting and anti-personnel departments on an even playing field.
University of London