Er, AFAIK, the leased Yes L15 is replacing the BWIA L15 undergoing heavy maintenance, which makes me wonder, how "heavy" this maintenance is. Sounds to me like this overhaul doesn't benefit BWIA at all anymore, because the aircraft would be back in BWIA service for only a few weeks or months until November.
However - and that was the basis of my question - I was asking for some more insight into this decision, which is, based on the information I got at the moment, hard for me to understand.
Your answer is not very helpful in this respect, "ooookkkaaaayyyy"?
Maybe my question was misleading. Hope it has become clearer now.
Homer: Facts are meaningless. You could use facts to prove anything that's even remotely true!