AD/BELL 412/29 - Tail Rotor Driveshaft Hangar Bearings

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of Australia, are a comprehensive set of rules governing civil aviation safety in the country. One part of these regulations, specifically PART 39 - 105, addresses Airworthiness Directives which are legal requirements aimed at ensuring that aircraft meet safety standards. The specific legislative instrument F2006B04663 focuses on the Bell Helicopter Textron 412 Series Helicopters, directing the mandatory compliance with certain maintenance procedures to address identified safety concerns. This particular directive was introduced to mitigate the risks associated with the tail rotor driveshaft hangar bearings, following a fatal accident that highlighted potential issues within a specific production batch. The policy objective is to enhance the safety of civil aviation by mandating rigorous and timely inspections and actions as outlined in relevant service bulletins and directives.

Scope and Application

The Civil Aviation Regulations 1998, under the jurisdiction of the Civil Aviation Safety Authority, specifically address the safety directives for the Bell Helicopter Textron 412 Series Helicopters through the legislative instrument F2006B04663. This particular regulation, AD/BELL 412/29, pertains to all models of the Bell Helicopter Textron 412 series equipped with tail rotor driveshaft bearings part number 204-040-623-003, where the serial number prefix is either “T” or “N” prior to N4000. This requirement mandates compliance with Bell Alert Service Bulletin 412-91-54 Revision A, as referenced in FAA Priority Letter AD 91-24-16, and demands that a daily inspection of the tail rotor driveshaft bearings is conducted before the first flight of the day following 27 November 1991. The directive emerged from the necessity for heightened safety measures following a fatal accident that suggested a potential production issue with these specific bearings.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, includes the Airworthiness Directives concerning various aircraft types, including the Bell Helicopter Textron 412 Series Helicopters. This particular directive, AD/BELL 412/29, addresses a critical safety concern related to the tail rotor driveshaft hangar bearings. The directive mandates that all Bell Helicopter Textron 412 Series models fitted with tail rotor driveshaft bearings P/N 204-040-623-003, which have serial numbers prefixed with either "T" or "N" before N4000, must adhere to the requirements outlined in Bell Alert Service Bulletin 412-91-54 Revision A. This action is mandated daily before the first flight of the day following 27 November 1991, as referenced in FAA Priority Letter AD 91-24-16. The obligations imposed by this directive are stringent and precise. Operators of the affected helicopters must conduct a thorough daily inspection of the specified tail rotor driveshaft bearings. This inspection is crucial to ensure the bearings are free from any defects or abnormalities that could compromise the safety of the aircraft. The directive leaves no room for deviation from the specified inspection procedure as outlined in the referenced service bulletin and FAA priority letter, underscoring the critical nature of the issue at hand. Failure to comply with this directive could have severe consequences. The safety of the aircraft and its occupants could be at risk if the required inspections are not performed as mandated. In the event of a non-compliance, there could be potential civil or criminal penalties imposed. While the specific penalties are not detailed in the directive itself, it is reasonable to infer that non-compliance with such a critical airworthiness directive could lead to significant repercussions under the broader Civil Aviation Act 1988, which includes fines and other regulatory actions. These actions are intended to ensure that safety standards are upheld and that any potential hazards are mitigated effectively.