Is it possible to grant a Part-147 approval to a training organisation which intend to conduct only training on one or only several modules?
No, a Part-147 approval can only be granted to an organisation which plans to conduct training on all the modules related to a (sub)category of an aircraft maintenance licence, so that a full understanding of the training needs, interfaces and examination relative to that (sub)category of licence is achieved.
However, some modules may be sub-contracted as mentioned in 147.A.145(d).
It does not mean that the Part-147 organisation is not allowed to conduct courses on just one module. In particular, in the case of limitations resulting from the conversion process, limitations can be lifted through the teaching and/or examination of one module or a part of a module.