AD/B747/161 - Triple Channel Autoland Autopilots

Overview

The Civil Aviation Regulations 1998, under Part 39 - 105, issued by the Civil Aviation Safety Authority (CASA), address a specific problem concerning the triple channel autoland autopilot systems in Boeing 747-100, -200, -300, and SP series aeroplanes. The legislation was introduced to ensure that flight crews are adequately informed about configuration changes to the autoland system, particularly during landing transitions from fail-operational to fail-passive modes. This is achieved through mandated modifications to the autopilot/flight director system wiring and the installation of certain components. The policy objective behind these regulations is to enhance flight safety by preventing potential misunderstandings or errors that might occur due to these system changes, thereby ensuring the continued airworthiness and safety of the aircraft. The compliance requirements outlined in the legislation mandate that specific modifications must be completed by certain deadlines, with further operational tests to be performed at regular intervals to maintain the integrity of the autoland system. This regulatory framework is designed to mitigate risks associated with system configurations that could potentially impact the safety of flight operations.

Scope and Application

The Civil Aviation Regulations 1998, under Part 39 - 105, specifically the Civil Aviation Safety Authority Schedule of Airworthiness Directives, includes provisions applicable to certain Boeing 747 series aeroplanes equipped with triple channel autoland autopilot systems. This legislation mandates particular modifications and operational tests to enhance the safety of these aircraft during landing. The directive, identified as AD/B747/161, applies to Boeing 747-100, -200, -300, and special programme (SP) series aeroplanes that meet the specified criteria, as referenced in Boeing Alert Service Bulletins 747-22A2212 Revision 1 dated 27 April 1995 and 747-22A2213 Revision 2 dated 22 June 1995. Compliance with these airworthiness directives is imperative to ensure that flight crews are properly informed of any configuration changes to the autoland system during landing, particularly when transitioning from a fail-operational to a fail-passive mode. The compliance deadlines and procedures are clearly outlined in the directive, with modifications to be completed prior to 31 December 1997, and operational tests to be performed before further flight after the initial modifications and subsequently at intervals not exceeding 20,000 hours of service time.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, incorporates Airworthiness Directives for various aircraft, including the Boeing 747 series aeroplanes. The particular directive AD/B747/161 (7/96) mandates the installation and testing of certain components in the autoland autopilot systems of the Boeing 747-100, -200, -300, and SP series aeroplanes. These modifications are necessary to ensure safe operation of the autoland system during landings. The directive references Boeing Alert Service Bulletins 747-22A2212 Revision 1 and 747-22A2213 Revision 2 as the basis for the required changes. Operators of Boeing 747 aeroplanes with triple channel autoland autopilot systems must comply with specific operational requirements. For Requirement 1, the installation of a diode and a marker on the E1-4, E1-5, and E1-6 shelves and the accompanying wiring changes to the flight mode annunciator must be completed by 31 December 1997. Upon completing this requirement, operators may apply to the local Civil Aviation Safety Authority Airworthiness District Office for the removal of certain operational limitations in the Aircraft Flight Manual. For Requirement 2, an operational test of the newly installed diodes must be conducted before further flights and at intervals not exceeding 20,000 hours of service time. Failure to adhere to the requirements of this Airworthiness Directive may result in non-compliance with the Civil Aviation Regulations 1998. Such non-compliance could potentially compromise the safety of the aircraft operations, leading to severe consequences, including grounding of the affected aircraft until the necessary modifications are completed. While the specific penalties for non-compliance are not detailed within this directive, violations of civil aviation regulations typically result in administrative, financial, and possibly criminal penalties, including fines and imprisonment, depending on the severity and intent of the breach. In summary, the Civil Aviation Regulations 1998 mandate specific modifications to the autoland systems of certain Boeing 747 aeroplanes to ensure flight safety. Operators must install specified components and perform operational tests in compliance with the referenced Boeing bulletins, within the stipulated timeframes. Non-compliance with these requirements may lead to significant regulatory and safety repercussions.