AD/B747/165 - Elevator Control System Modifications

Overview

The Civil Aviation Regulations 1998, which were enacted by the Parliament of Australia, aim to ensure the safety and regulation of civil aviation within Australia. This legislation provides the legal framework for the Civil Aviation Safety Authority (CASA) to issue airworthiness directives to address specific safety concerns. Part 39 - 105 of the Civil Aviation Regulations 1998 includes a schedule of airworthiness directives, such as AD/B747/165, which was introduced to address a problem identified with certain Boeing 747 series aeroplanes. This specific directive was introduced to rectify issues with the elevator control system, particularly for certain models and serial numbers of the Boeing 747-200, -300, and -400 series aeroplanes. The policy objective of this directive is to mitigate the risk of uncommanded elevator deflections and control column 'bumps', which could potentially lead to structural damage and compromised controllability of the aircraft.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, pertains to the maintenance and safety directives issued by the Civil Aviation Safety Authority (CASA) and applies to all aviation entities within Australia, including aeroplane manufacturers, operators, and maintenance service providers. This legislative instrument targets Boeing 747-200, -300, and -400 series aeroplanes that meet certain specifications, namely those with a cumulative line number (C/L) between 696 and 1057 inclusive, and are equipped with specific Parker inboard elevator power control packages. The modifications outlined in this directive are mandatory for all aeroplanes certificated in any category and aim to address reported instances of uncommanded right elevator deflections and control column 'bumps', which could compromise the structural integrity and controllability of the aircraft. Compliance with the modifications must be achieved within specified timeframes, with critical actions needing completion within 12 months of the directive's effective date and other modifications within three years. This directive, effective from 30 January 1997, ensures that all applicable aircraft meet necessary safety standards to mitigate the risks identified by the FAA.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, include a schedule of airworthiness directives, such as AD/B747/165 which pertains to elevator control system modifications for certain Boeing 747 series aeroplanes. Section 1 of this directive mandates that the hydraulic tubing of the right inboard elevator power control packages (PCP) for Model 747-400 aeroplanes be modified as specified in Boeing Alert Service Bulletin 747-27A2348, Revision 1, dated January 26, 1995. For all applicable aeroplanes, including Models 747-200, -300, and -400 series, the left and right servo assemblies of the inboard elevator PCP must also be modified according to Parker Service Bulletin 327400-27-171, Revision 1, dated April 14, 1995, or Parker Service Bulletin 93600-27-173 dated May 17, 1995 as applicable. These modifications are designed to prevent uncommanded elevator deflections, which could lead to structural damage and reduced controllability of the aircraft. The Civil Aviation Regulations impose specific obligations on the operators of the Boeing 747 series aeroplanes covered by AD/B747/165. Operators must ensure that the modifications to the hydraulic tubing and servo assemblies are carried out within the stipulated timelines. For Model 747-400 aeroplanes, the hydraulic tubing modification must be completed within 12 months of the effective date of the directive, which is 30 January 1997. For all applicable aeroplanes, modifications to the servo assemblies must be completed within three years of the directive's effective date. Compliance with these deadlines is critical to maintaining the airworthiness of the aircraft and ensuring passenger safety. Failure to comply with the requirements set out in AD/B747/165 can lead to serious consequences. The Civil Aviation Regulations provide for both civil and criminal penalties for non-compliance with airworthiness directives. Civil penalties may include fines, while criminal penalties could result in imprisonment. The exact penalties are determined by the severity of the breach and the impact on aviation safety. The potential for structural damage and reduced controllability of the aircraft underscores the importance of adhering to these modifications to prevent accidents and ensure the continued safe operation of the Boeing 747 series aeroplanes.