Overview

The Civil Aviation Regulations 1998, specifically Part 39 - 105, includes an Airworthiness Directive issued by the Civil Aviation Safety Authority (CASA) to address safety concerns in Boeing 747-400 series aircraft powered by Pratt and Whitney PW4000 engines. This legislation, known as AD/B747/237, was enacted to rectify the issue of excessive wear in the thrust reverser auxiliary track beam assemblies, which could lead to the disengagement of a slider and separation of a portion of the thrust reverser, potentially causing damage to the aircraft structure or posing a hazard to people on the ground. The directive mandates initial and repetitive inspections of the thrust reverser auxiliary beam assemblies, incorporating improved liner and slider assemblies, and specifies compliance timelines for these actions. The policy objective is to ensure the safe operation of the aircraft by mitigating the identified unsafe condition.

Scope and Application

The Airworthiness Directive issued under the Civil Aviation Regulations 1998 applies specifically to Boeing 747-400 series aircraft that are powered by Pratt and Whitney PW4000 engines and fall within line numbers 696 through 1100 inclusive. This directive, issued by the Civil Aviation Safety Authority (CASA) delegate, is aimed at ensuring the safety of these aircraft by addressing a critical issue related to the thrust reverser auxiliary track assembly. The directive requires operators to conduct thorough inspections and necessary repairs or replacements of the thrust reverser auxiliary beam assemblies, as well as the incorporation of improved liner and slider assemblies to mitigate the risk of disengagement and potential damage. This mandate is enforced across the entire Commonwealth of Australia, underscoring the importance of adhering to these safety measures to prevent hazards to both the aircraft and persons on the ground. The directive became effective on 30 November 2000 and is subject to specific compliance timelines outlined within the directive itself.

Key Provisions

This Airworthiness Directive (AD), specifically AD/B747/237, targets Boeing 747-400 series aircraft powered by Pratt and Whitney PW4000 engines within the specified line numbers 696 through 1100. The directive mandates actions to address a critical issue identified with the thrust reverser auxiliary track assembly, which can lead to disengagement and separation of thrust reverser components. This could potentially damage the aircraft or pose a risk to individuals on the ground. The AD requires two main actions: first, conducting initial and repetitive inspections of the thrust reverser auxiliary beam assemblies, following the technical instructions in FAA AD 2000-11-28, Paragraph (a), and repairing or replacing any defective parts before further flights; second, incorporating improved liner and slider assemblies as per FAA AD 2000-11-28, either Paragraph (b) or (c), depending on the specific circumstances. Compliance with the second requirement is considered the terminating action for the inspections outlined in the first requirement for each modified beam assembly. The AD imposes specific obligations on the operators of the affected Boeing 747-400 aircraft. They must adhere to the inspection and repair procedures detailed in FAA AD 2000-11-28, ensuring that the thrust reverser auxiliary beam assemblies are thoroughly examined and any discrepancies are addressed promptly. Additionally, operators must incorporate the improved liner and slider assemblies as specified in FAA AD 2000-11-28. These obligations are designed to mitigate the risk of thrust reverser disengagement and separation, thereby ensuring the safety of the aircraft and those on the ground. Operators must also ensure that these actions are carried out in compliance with the specified timelines and by certified personnel. Failure to comply with this Airworthiness Directive could result in severe consequences, both legally and operationally. Non-compliance could lead to the aircraft being deemed unsafe to operate, potentially resulting in grounding and significant operational disruptions. Furthermore, if non-compliance contributes to an accident or incident, operators could face both civil and criminal penalties, including fines and imprisonment. The exact penalties would depend on the severity of the non-compliance and the resulting consequences. Therefore, it is imperative that operators strictly adhere to the requirements set out in this AD to avoid any potential legal repercussions and ensure the continued airworthiness of the aircraft.