Thank you for that link, drflight! It answers one of my questions, namely that FlightlineBCN's AOC is issued in Spain.
"what next", there is quite a bit of commentary earlier in the thread about the operation of the Garretts, which I referenced in a summary post. No one else I know with experience flying the Metroliner has yet answered this question for me - can you explain how the prop blades on the left engine became bent in the way they did?