In reply to Just this Once
The Yak-52 being on a PtF is irrelevant, it's either airworthy or it's not - in this case NOT airworthy. I've seen enough PtF aircraft and flown some and being on a PtF is not an excuse for poor maintenance/adherence to AD's.
Agree with the other posters that this is banana republic territory.
This was an accident waiting to happen compounded by what appears to be a level of complacency that beggars belief.