This proposed rule would amend the airworthiness standards for fatigue tolerance evaluation (FTE) of transport category rotorcraft metallic structures.  This proposal would revise the FTE safety requirements to address advances in structural fatigue substantiation technology for metallic structures.  This provides an increased level of safety by avoiding or reducing catastrophic fatigue failures of metallic structures.  These increased safety requirements would help ensure that should serious accidental damage occur during manufacturing or within the operational life of the rotorcraft, the remaining structure could withstand, without failure, any fatigue loads that are likely to occur, until the damage is detected or the part is replaced.  Besides improving the safety standards for FTE of all principal structural elements (PSEs), the proposed amendment would be harmonized with international standards.

Protection of  human life