AD/DHC-6/70 - Horizontal Stabiliser - Centre Hinge Bracket Flange

Overview

The Civil Aviation Regulations 1998, specifically PART 39 - 105 Civil Aviation Safety Authority Schedule of Airworthiness Directives, was enacted to ensure the safety and maintenance standards of aircraft operating in Australia. This regulation addresses issues pertaining to the maintenance and safety of DHC-6 (Twin Otter) Series Aeroplanes, particularly focusing on the horizontal stabiliser centre hinge bracket flange, as indicated in AD/DHC-6/70. The problem it seeks to mitigate is the reported in-service cracking of the horizontal stabiliser centre hinge bracket flange, which poses a safety risk to aircraft operation. The regulation was enacted by the Civil Aviation Safety Authority (CASA), with the policy objective of enhancing aircraft safety through mandatory inspections and maintenance requirements. This legislation mandates a fluorescent dye penetrant inspection of all flanges of the Horizontal Stabiliser Hinge Bracket, to be performed in accordance with de Havilland Canada Service Bulletin 6/512 Revision 1, ensuring that any potential defects are identified and addressed promptly. The requirement for initial inspection within 250 hours of time in service following 27 April 1995, and subsequent re-inspections at intervals not exceeding 1200 hours, underscores the importance of regular maintenance to prevent potential structural failures. This directive is designed to maintain the airworthiness of DHC-6 aircraft, thereby safeguarding passengers and crew, and aligns with international standards as referenced by Transport Canada AD CF-92-05. The legislation's focus on stringent inspection intervals, irrespective of hinge bracket replacement, highlights a commitment to proactive safety measures within the aviation industry.

Scope and Application

The Civil Aviation Safety Authority's regulations under the Civil Aviation Act 1988, specifically detailed in Part 39 - 105 of the Civil Aviation Regulations 1998, mandate that all operators of DHC-6 (Twin Otter) series aeroplanes must adhere to Airworthiness Directives concerning the horizontal stabiliser centre hinge bracket flange. These directives apply to all aircraft within the DHC-6 model, irrespective of their operational context or geographic location within Australia, ensuring a uniform standard of maintenance and safety across the industry. The requirement is to conduct fluorescent dye penetrant inspections on the flanges of the Horizontal Stabiliser Hinge Bracket P/N C6TPM1021, as per de Havilland Canada Service Bulletin 6/512 Revision 1, reflecting a directive from Transport Canada. Compliance with these regulations necessitates an initial inspection within 250 hours of time in service after 27 April 1995, followed by repeat inspections at intervals not exceeding 1200 hours, regardless of any replacement of the hinge bracket. These measures are crucial as reports have surfaced of in-service cracking in the horizontal stabiliser centre hinge bracket flange, emphasising the importance of rigorous inspection protocols.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, mandate certain airworthiness directives for the DHC-6 (Twin Otter) Series Aeroplanes. One such directive is AD/DHC-6/70, which pertains to the horizontal stabiliser centre hinge bracket flange (Section 5/95). According to this directive, all DHC-6 model aircraft must undergo a fluorescent dye penetrant inspection of all flanges of the Horizontal Stabiliser Hinge Bracket P/N C6TPM1021. This inspection must be conducted in accordance with de Havilland Canada Service Bulletin 6/512 Revision 1. The directive references Transport Canada AD CF-92-05 for additional guidance. The obligations imposed by this directive require operators of DHC-6 model aircraft to ensure that the specified inspections are carried out meticulously. The initial inspection must be completed within 250 hours of time in service after 27 April 1995. Subsequently, re-inspections must be conducted at intervals not exceeding 1200 hours of time in service. It is crucial that these inspections occur regardless of whether the hinge bracket has been replaced. Compliance with these requirements is essential to maintain the airworthiness of the aircraft and to address the issue of in-service cracking that has been reported in the horizontal stabiliser centre hinge bracket flange. Failure to comply with the airworthiness directives stipulated in the Civil Aviation Regulations 1998 can lead to serious consequences. The regulations outline specific offences and penalties for non-compliance. While the exact penalties are not detailed in the provided text, it is known that breaches of these safety directives can result in significant civil or criminal consequences. The severity of these consequences can vary, but they are designed to ensure that all aircraft maintain the highest standards of safety and reliability. Operators must be diligent in adhering to these requirements to avoid potential legal ramifications and to ensure the continued safe operation of their aircraft.