Overview

The Civil Aviation Safety Authority Airworthiness Directive AD/GBK 117/14 was enacted in 2003 to address the problem of cracks found in the cage cover of certain bearings installed in the tail rotor transmissions and intermediate gearboxes of Eurocopter BK 117 series helicopters. This Airworthiness Directive was issued by the Civil Aviation Safety Authority (CASA) as a response to reports of bearing failures that could result in the failure of the tail rotor transmission or intermediate gearbox, leading to the potential loss of helicopter control. The directive requires inspections and specific actions to be taken to ensure the safe operation of the affected aircraft. The objective of the directive is to correct the unsafe condition by mandating necessary actions to be taken by operators in relation to the specified aircraft models and components.

Scope and Application

The Airworthiness Directive issued under subregulation 39.1(1) of the Civil Aviation Safety Regulations 1998 pertains specifically to the Eurocopter BK 117 Series Helicopters, focusing on tail rotor drive bearings. This directive applies to MBB-BK117 helicopters with certain model specifications, serial numbers, and part numbers, specifically those that include tail rotor transmission part numbers 4639003001 or 4639003007 with serial numbers 900 through 932, intermediate gearbox part numbers 4639002001 or 4639002005 with serial numbers 902 through 928, or those that have been overhauled or repaired between 16 July 2001 and 14 April 2003. Additionally, it covers tail rotor transmissions and intermediate gearboxes fitted with bearing part number 4639310006, serial numbers 3246 through 3598, provided they have not been inspected in accordance with specified Eurocopter Alert Service Bulletin paragraphs. The directive mandates various inspections and actions to ensure the airworthiness of these components, with compliance deadlines set before the first flight of the day pending certain inspections and by 31 January 2004 for other specified actions.

Key Provisions

This Airworthiness Directive (AD) applies to specific models of Eurocopter BK 117 helicopters, specifically the A-1 through C-1 models, with certain tail rotor transmission and intermediate gearbox parts that fall within specified serial number ranges or that were overhauled or repaired within a particular time frame (sections 1-3). The directive mandates a series of actions to address an unsafe condition identified in the tail rotor drive bearings. Firstly, operators must inspect the magnetic plugs of the tail rotor transmissions and intermediate gearboxes in accordance with detailed instructions provided in the referenced Eurocopter Alert Service Bulletin (ASB) MBB-BK117-30-108 Revision 1 (section 1). Additionally, operators must supply specific serial numbers of any tail rotor transmissions and intermediate gearboxes overhauled or repaired between 16 July 2001 and 14 April 2003 to ZF Lufthfahrttechnik, if this has not been done previously (section 2). Moreover, operators must conduct thorough inspections of both installed and spare tail rotor transmissions and intermediate gearboxes according to Paragraph 2.B.2 of the aforementioned Eurocopter ASB, ensuring compliance with these requirements before the first flight of the day, by 31 January 2004, and prior to installation in a helicopter (sections 3 and 4). These obligations are critical to ensuring the airworthiness and safety of the specified helicopter models. Operators of the affected Eurocopter BK 117 helicopters must comply with the specified inspection and reporting requirements as outlined in the AD (section 1). This includes conducting inspections of the magnetic plugs of the tail rotor transmissions and intermediate gearboxes using the detailed instructions provided in the Eurocopter ASB MBB-BK117-30-108 Revision 1. Furthermore, operators are required to provide specific serial numbers of any overhauled or repaired parts to ZF Lufthfahrttechnik if this has not already been completed (section 2). Additionally, operators must ensure that all inspections of installed and spare parts are performed according to the instructions in the Eurocopter ASB before the first flight of the day, by the specified deadlines, and prior to installation (sections 3 and 4). Compliance with these obligations is necessary to mitigate the risk of bearing failure and ensure the continued safe operation of the affected helicopters. Failure to comply with the requirements set out in this AD can result in significant legal and safety consequences. The directive explicitly states that non-compliance could lead to unsafe conditions that might compromise the airworthiness and operational safety of the helicopters (section 1). Although the AD does not explicitly detail specific penalties or consequences for non-compliance, violations of airworthiness directives generally carry severe implications under Australian aviation law. These could include enforcement actions by the Civil Aviation Safety Authority (CASA), potential grounding of non-compliant aircraft, and civil or criminal penalties for operators found to be in breach of the regulations. The overarching objective of this AD is to ensure the safety of aircraft operations by mandating necessary inspections and corrective actions to prevent bearing failures in the tail rotor transmissions and intermediate gearboxes of the specified Eurocopter BK 117 helicopters.