AD/BELL 47/17 Amdt 1 - Tail Rotor Pitch Change Bearings - Inspection and Life Limitations

Overview

The Civil Aviation Regulations 1998, amended under Part 39 - 105, introduces specific Airworthiness Directives for the Bell Helicopter Textron 47 series, addressing issues pertinent to the safety of these aircraft. This directive, AD/BELL 47/17 Amendment 1, specifically targets the tail rotor pitch change bearings to ensure that they meet necessary safety standards. The directive was enacted by the Civil Aviation Safety Authority to address the identified problem of bearing wear and potential failure, which could compromise the operational safety of the aircraft. The overarching policy objective is to maintain and enhance the safety of civil aviation within Australia, ensuring that all aircraft meet stringent safety criteria as prescribed by the regulatory authority. Compliance with this directive is mandatory for all model 47D and D1, 47G, G2, and H1 helicopters. Operators must conduct a thorough inspection of the pitch change control shaft and ensure its concentricity, as well as adhere to the specified life limitations for the tail rotor pitch change bearings. Non-compliance with these directives could result in significant safety risks, thereby undermining the overall integrity of the civil aviation system.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39, Section 105, mandates the issuance of airworthiness directives by the Civil Aviation Safety Authority, applicable to all model 47D and D1, 47G, G2, and H1 Bell Helicopter Textron 47 Series helicopters. These regulations apply to the inspection and life limitations of tail rotor pitch change bearings in the mentioned helicopter models. The directive applies to all aircraft owners or operators of the specified Bell 47 variants, requiring them to adhere to the outlined inspection and maintenance procedures. The geographic scope of these regulations is national, applying across the Commonwealth of Australia. There are no stated exclusions or exemptions within the provided text, meaning all relevant aircraft must comply with the stipulated requirements. The application of these directives may be further detailed or extended through subordinate instruments or additional amendments issued by the Civil Aviation Safety Authority.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, addresses the airworthiness directives for Bell Helicopter Textron 47 Series helicopters. Under this directive, the main focus is on the inspection and life limitations of the tail rotor pitch change bearings (sections 1 and 2). All model 47D and D1, 47G, G2 and H1 helicopters are subject to this directive, which applies to the tail rotor pitch change control shaft parts numbers 47-641-034 or 47-641-045. The regulation mandates that these parts be inspected to ensure the concentricity of the bearing shaft diameter is within 0.060 TIR. If the diameters are not concentric within this tolerance, the shaft must be straightened to meet the required specification. Additionally, the tail rotor pitch change bearings with specific part numbers must be retired from service after 100 hours of time in service or in accordance with FAA AD 58-23-1. The Civil Aviation Regulations impose several obligations on the operators and maintainers of the specified Bell Helicopter Textron 47 Series helicopters. Firstly, these parties are required to conduct an inspection of the tail rotor pitch change control shaft at intervals not exceeding 600 hours of time in service after 1 September 1971. The inspection must follow the detailed steps outlined in the Bell Service Manual, including the removal of the shaft from the tail rotor gearbox, mounting it in a collet at the acme screw thread end, and measuring the concentricity of the bearing shaft diameter. If the measurements do not meet the specified concentricity tolerance, the shaft must be straightened accordingly. Furthermore, the specific tail rotor pitch change bearings must be retired from service after they accumulate 100 hours of time in service or in compliance with the FAA AD 58-23-1. Failure to comply with the requirements set forth in the Civil Aviation Regulations can lead to various consequences. Although specific penalties are not detailed in this directive, non-compliance generally results in civil or criminal actions under the broader Civil Aviation Act 1988. Civil penalties may include fines, while criminal penalties could involve imprisonment, depending on the severity and intent of the breach. Operators and maintainers are expected to adhere strictly to the inspection and replacement schedules to ensure the airworthiness and safety of the aircraft, thereby avoiding any potential legal repercussions.