The weak link on most Bell helicopters has been the tailboom. The proverbial Achilles tendon. Didn't matter the model they would fix one issue then it would move to a different place and crack it there. Throw in inconsistent maintenance practices across the spectrum and it would surface with some unsuspecting operator. For example, the upper LH tailboom mount area on all 206L/407 models has been cracking for eons with the 407 improvements initially moving the crack forces to the upper and lower TB skins. Is it a bad design... I don't think so but its not very tolerant of bad or irregular mx. Same reason behind the Bell 24 month flight control bolt inspections and lube requirements. One operator didn't remove the majority of those bolts for over 10 years and one broke. Every helicopter model has some sort of weak link, some just get more press than others.