Just an idle question, but am curious about whether such older aircraft, no matter in which country, undergo major overhauls by in-house personnel or by outsourced contract work.
A primary question can concern whether an airline's line technicians/engineers are required by managers to sign off daily repair work in maintenance log books-even if the work is not done. This situation has been discovered by Safety Officers with at least one US major airline.
Turboprops might have even more potential for trouble than jets, because of the complex propeller systems. A buddy told me that in ground school for the FH-227, they spent about a whole day covering the propellor controls and blade angle indicator lights etc.
My condolences to the families and victims of those tragedies.