AD/APU/12 - Compressor Wheel

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of Australia, form a comprehensive set of rules governing all aspects of civil aviation in the country. This legislation was introduced to address the need for stringent safety standards and compliance measures to ensure the safe operation of aircraft within and beyond Australian airspace. Specifically, Part 39 - 107 Civil Aviation Safety Authority Schedule of Airworthiness Directives addresses the safety and maintenance requirements for various aircraft components. The policy objective of these regulations is to mitigate risks and enhance the overall safety of civil aviation operations. One such directive, AD/APU/12, pertains to the compressor wheels of Sundstrand Aerospace T-62T-40C series Auxiliary Power Units. This directive was introduced in response to reported failures due to fatigue cracks, aiming to prevent uncontained Auxiliary Power Unit failures that could potentially damage an aircraft. Compliance with these directives is mandatory, and failure to adhere to them can result in serious safety implications.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 107, outlines the application of the Airworthiness Directives concerning auxiliary power units, including the requirement to replace affected compressor wheels for certain Sundstrand Aerospace T-62T-40C series Auxiliary Power Units. This directive applies to any aircraft operating within the Commonwealth of Australia that utilises the specified Sundstrand Aerospace T-62T-40C series Auxiliary Power Units with the affected compressor wheels identified by the part numbers 162690-1, 165111-1, or 167200-1. The directive mandates the replacement of these compressor wheels in line with the instructions provided in the Sundstrand Aerospace Service Bulletin T-62T-49-120 Revision 2 dated 5 November 1996, and also references FAA AD 96-25-12. The directive became effective on 17 July 1997, and compliance is to be ensured as detailed in the requirement document. This directive aims to mitigate the risk of uncontained auxiliary power unit failures that could potentially cause damage to an aircraft due to fatigue cracks propagating from screw holes on the backface of the compressor wheel.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 107 (section 107.030), mandate the implementation of Airworthiness Directives (ADs) issued by the Civil Aviation Safety Authority (CASA). In this context, AD/APU/12 pertains to the Sundstrand Aerospace T-62T-40C series Auxiliary Power Units (APU) that include specific compressor wheels identified by part numbers 162690-1, 165111-1, or 167200-1. The directive requires that affected compressor wheels be replaced following the guidelines provided in Sundstrand Aerospace Service Bulletin T-62T-49-120 Revision 2 dated 5 November 1996. This replacement is crucial to mitigate the risk of fatigue cracks originating from screw holes on the backface of the compressor wheel, which could lead to uncontained APU failures and subsequent aircraft damage. Compliance with this AD is mandatory for all operators of the specified Sundstrand Aerospace T-62T-40C series APUs. Operators must ensure that the compressor wheels are replaced in accordance with the detailed instructions provided in the referenced service bulletin. This directive became effective on 17 July 1997, setting a clear deadline for operators to implement the necessary changes. The compliance process must align with the requirements outlined in the directive to maintain the airworthiness of the aircraft. The obligations imposed on the parties governed by this AD include conducting a thorough inspection of the compressor wheels in the specified APUs to identify those requiring replacement. Operators must source the correct replacement parts and ensure that the replacement process is executed by qualified personnel. Documentation of the inspection, identification of affected parts, and the replacement process must be maintained as evidence of compliance. Failure to adhere to the AD may result in the aircraft being deemed unairworthy, which could lead to grounding and significant operational disruptions. Breach of the AD/APU/12 provisions could result in severe consequences, including both civil and criminal penalties. Civil penalties may include fines and sanctions imposed by CASA, which can vary depending on the severity and frequency of the breach. In more serious cases, criminal charges may be filed, leading to substantial fines and potential imprisonment for responsible individuals. The exact penalties are not specified in the AD itself but are determined by the applicable aviation safety regulations and relevant civil and criminal laws. Ensuring strict adherence to the AD is therefore imperative to avoid these potential consequences.