IMHO the age of the aircraft and how many hours it has done are not a factor provided the maintenance is up to speed, which I'm sure it was in the above cases. (The SFC C172s are the latest model) There's been a lot of bad luck around YPJT in the last few days, but it's a tribute to safety and pilot skill that no-one has been hurt, and that these have been "forced landings" rather than "crashes" whatever the media want to call them.