AD/B747/144 - Engine Thrust Control - Idler Cable Pulley Support Bracket

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of the Commonwealth of Australia, are a comprehensive set of rules designed to ensure the safety and efficiency of civil aviation within Australia. One particular regulation, AD/B747/144, was introduced to address the specific issue of cracks in the thrust control cable idler pulley support brackets of Boeing 747 Series Aeroplanes equipped with GE CF6-45/50 engines. This regulation was developed in response to reported instances of bracket failure that could potentially result in the loss of engine thrust control. The policy objective of this directive is to ensure that these aeroplanes are maintained in a safe and airworthy condition through regular inspections and necessary repairs or replacements of the affected components.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, issued by the Civil Aviation Safety Authority, mandate the issuance of Airworthiness Directives (AD) to ensure the safety of aircraft operations. This particular AD, AD/B747/144, applies to Boeing 747 series aeroplanes, specifically line numbers 202 to 886 inclusive, which are equipped with GE CF6-45/50 engines. The directive necessitates a visual inspection of the number 1 strut engine thrust control cable idler pulley support bracket for any signs of cracking, in compliance with Boeing Service Bulletin 747-76A2083. Brackets exhibiting a single crack less than 2.0 inches in length may remain in service if an interim repair is installed as per Boeing SB 747-76A2083 Revision 1. Moreover, these brackets must be replaced with ones made of Inconel 625, in accordance with Boeing SB 747-76A2083 Revision 2. The directive mandates inspections before the aircraft reaches 9000 hours of time in service or within 600 hours from 27 April 1995, whichever is later, and re-inspections at intervals not exceeding 600 hours. Brackets with the interim repair must be inspected at intervals not exceeding 100 hours, and interim repaired brackets must be replaced within 750 hours from the installation of the repair. Furthermore, all brackets must be replaced before 10 November 1995. The replacement of brackets with those made from Inconel 625 negates the need for further inspections under this AD.

Key Provisions

The Civil Aviation Regulations 1998, specifically under Part 39 - 105, address the airworthiness directives for certain aircraft, including Boeing 747 Series aeroplanes. AD/B747/144 pertains to the engine thrust control idler cable pulley support bracket and is applicable to Boeing 747 line numbers 202 to 886 equipped with GE CF6-45/50 engines. The directive sets out the requirements for inspecting and, if necessary, replacing the idler pulley support bracket to ensure continued airworthiness and safety. The primary requirement is to visually inspect the number 1 strut engine thrust control cable idler pulley support bracket for cracks, with specific guidance provided in Boeing SB 747-76A2083. Compliance with these requirements entails several obligations for the parties governed by the Act. Firstly, operators must inspect the brackets before the aircraft reaches 9000 hours of time in service or within 600 hours from 27 April 1995, whichever is later. This inspection must be repeated at intervals not exceeding 600 hours of time in service. For brackets that have undergone interim repair as per Requirement 1, inspections must be conducted at intervals not exceeding 100 hours. Operators are also required to replace interim repaired brackets within 750 hours from the installation of the repair and ensure all brackets are replaced with those made of Inconel 625 before 10 November 1995. The replacement of these brackets cancels the inspection requirements outlined in this AD. Failure to comply with the directives outlined in the Civil Aviation Regulations 1998 can lead to significant consequences. The Civil Aviation Act 1988 and the Civil Aviation Regulations 1998 provide for both civil and criminal penalties for non-compliance. Civil penalties may include fines and enforcement actions against the operator, while criminal penalties may apply in cases of gross negligence or willful disregard for the safety directives. The exact penalties are not specified in the provided text, but they can be substantial, reflecting the critical importance of adhering to airworthiness directives to ensure the safety of air travel.