AD/APU/13 - Augmentation Containment Ring

Overview

The Civil Aviation Regulations 1998, enacted by the Commonwealth of Australia, address the safety of civil aviation, including the regulation of airworthiness. One specific legislative instrument, F2006B02431, focuses on the airworthiness directives for auxiliary power units (APUs). This instrument was introduced to address a critical safety issue identified with certain models of auxiliary power units, specifically those manufactured by AlliedSignal Inc. The problem it seeks to resolve is the potential failure of the Hastelloy S containment shield, which could lead to the rupture of a one-piece cast turbine wheel and the non-containment of high-energy rotor fragments. Such failures could compromise the fire protection capability of the APU and potentially cause significant damage to the aircraft structure. The policy objective is to ensure that these units meet specified safety standards to prevent such incidents, thereby enhancing overall aviation safety.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 107 under the Civil Aviation Safety Authority's Schedule of Airworthiness Directives, mandates the installation of a containment augmentation ring for AlliedSignal Inc.'s GTCP85 series auxiliary power units (APUs) equipped with a one-piece cast turbine wheel, identified by part numbers 968095-xx, 3604604-xx, 3606982-xx, or 3842072-xx. This directive applies to all APUs used in civil aviation and ensures that these units meet specific safety standards to prevent the failure of the Hastelloy S containment shield, which has been known to fail and result in the release of high-energy fragments that can penetrate the APU compartment, potentially compromising fire protection capabilities and causing damage to the aircraft structure. The directive requires compliance within 24 months for flight-operable APUs and 36 months for ground-operable APUs from the effective date of 17 July 1997. This directive supersedes AD/APU/6 Amendment 1 and aligns with FAA AD 97-04-04.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39, include Airworthiness Directives (ADs) which are regulatory measures aimed at ensuring the safety of aircraft. One such AD, AD/APU/13, pertains to the installation of a containment augmentation ring for certain auxiliary power units (APUs) manufactured by AlliedSignal Inc. The directive applies to GTCP85 series APUs with specific part numbers: 968095-xx, 3604604-xx, 3606982-xx, and 3842072-xx (section 1). The requirement is to install a containment augmentation ring following either AlliedSignal Aerospace Alert Service Bulletin GTCP85-49-A6706 Revision 2 or GTCP85-49-A7189 Revision 2 (section 2). It is noted that FAA AD 97-04-04 also references this directive and that it supersedes AD/APU/6 Amdt1. The AD mandates compliance within specific timeframes: for APUs that are operable in flight, compliance is required within 24 months from the directive's effective date, while for APUs that are only operable on the ground, the compliance period extends to 36 months (section 3). This directive became effective on 17 July 1997. The directive was issued in response to an incident where a Hastelloy S containment shield, introduced by AlliedSignal Service Bulletin GTCP85-49-5700, failed to contain fragments following a rupture of a one-piece cast turbine wheel. The failure to contain these fragments can lead to penetration of the APU compartment, compromising the fire protection capability of the APU and potentially causing structural damage to the aircraft (section 4). Entities and parties governed by the Civil Aviation Regulations 1998, including aircraft operators and maintenance providers, are obligated to ensure that the specified APUs are fitted with the required containment augmentation ring within the stipulated timeframes. Failure to comply with the AD can result in the APU being deemed unairworthy, thereby preventing the aircraft from being operated until the compliance requirement is met. This requirement is crucial to maintaining the safety standards mandated by the Civil Aviation Safety Authority (CASA) and the Federal Aviation Administration (FAA). Failure to comply with the provisions of AD/APU/13 can lead to serious consequences. The Civil Aviation Regulations 1998 stipulate that non-compliance with an AD can result in various penalties. Civil penalties may include fines and potential suspension or revocation of an operator’s certificate. In more severe cases, criminal charges may be applicable, particularly if the non-compliance leads to an incident or accident. The maximum penalties for such offences can include substantial fines and imprisonment, depending on the severity and impact of the non-compliance. Ensuring adherence to AD/APU/13 is, therefore, not only a regulatory requirement but also a critical safety measure to prevent potential accidents and ensure the safe operation of aircraft.