Helicopter blade bolts must be replaced after manufacturing defect

The US aviation regulator is ordering the replacement of specific blade bolts on Bell Textron Canada Limited Model 407 and 427 helicopters. This is because some bolts may not have been properly heat-treated, which could cause them to crack.

This is a safety recall for a specific part on specific helicopter models. It means operators of these helicopters must inspect and replace the bolts to prevent potential failures. The change is about preventing a known risk, not about changing how helicopters are designed or regulated more broadly.