To elaborate on that....the qualified (on type?) mechanic should crawl over every inch; take as long as he/she wants, days if necessary, and hang on to the payment until he/she is good and ready. Do a long and searching test flight (incl C of A test, as per above).
IT'S A GIVEN THAT THERE WILL BE SOMETHING THAT HAS NOT BEEN DONE RIGHT. What your team has to do is find it before accepting the aircraft, and not halfway across the pond. Don't let them tell you they've done all the checks so you don't need to bother. They will have, but it's your team's safety at stake.