AD/DHC-6/58 - Wing Struts Internal Beam Corrosion

Overview

The Civil Aviation Safety Authority (CASA) issued Airworthiness Directive (AD) DHC-6/58 in 1985 under the authority vested by the Civil Aviation Act 1988 to ensure the safety of aircraft operations within Australia. This legislative instrument addresses the specific issue of internal beam corrosion in the wing struts of DHC-6 (Twin Otter) Series aeroplanes, which can compromise the structural integrity of the aircraft. CASA mandated compliance with De Havilland Aircraft of Canada Service Bulletin No. 6/474 to rectify the identified corrosion in the strut beam flanges, thereby maintaining the airworthiness of the affected aircraft and safeguarding the travelling public. The directive was enacted to ensure that all models of DHC-6 Twin Otter aeroplanes adhere to the specified maintenance and inspection requirements to prevent the progression of corrosion.

Scope and Application

The Civil Aviation Regulations 1998, specifically under PART 39 - 105, pertain to the Civil Aviation Safety Authority's Schedule of Airworthiness Directives, which applies to all DHC-6 (Twin Otter) series aeroplanes. The regulation mandates that all operators of these aircraft adhere to the requirements outlined in De Havilland Aircraft of Canada Service Bulletin No.6/474 to address issues of internal beam corrosion in the wing struts. Compliance with this directive is essential to ensure the airworthiness and safety of these aircraft. The regulation applies to all models of the DHC-6 Twin Otter series, thereby encompassing a broad range of operators within the aviation industry. Given that the Civil Aviation Regulations 1998 are Commonwealth regulations, their application extends across Australia, ensuring a uniform standard of aircraft safety nationwide. No specific exclusions or exemptions are mentioned in the directive, implying that all applicable aircraft must comply with the prescribed action to mitigate the risk of exfoliation corrosion in the strut beam flanges.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, pertains to the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives, focusing on DHC-6 (Twin Otter) series aeroplanes. Under this section, Airworthiness Directive AD/DHC-6/58 addresses the critical issue of wing struts internal beam corrosion (section 9/85). This directive applies to all models of DHC-6 series aeroplanes (section 9/85). The directive requires compliance with De Havilland Aircraft of Canada Service Bulletin No.6/474, which outlines specific actions to mitigate the identified corrosion in the strut beam flanges enclosed by the strut skins (section 9/85). The obligations imposed by this Airworthiness Directive mandate that operators of DHC-6 series aeroplanes must adhere to the prescribed actions detailed in the aforementioned service bulletin. This includes conducting thorough inspections and, if necessary, repairs or replacements of the affected wing struts to prevent exfoliation corrosion (section 9/85). Operators must ensure that all maintenance and repair activities are performed in accordance with the manufacturer's guidelines to maintain the airworthiness of the aircraft. Failure to comply with the provisions of AD/DHC-6/58 can result in significant legal and safety consequences. The regulations stipulate that non-compliance may lead to enforcement actions by CASA, including the potential grounding of the aircraft until the required actions are completed (section 9/85). Additionally, operators found in breach of these directives may face civil penalties, including fines, as well as criminal charges if the non-compliance results in a safety hazard or incident. The maximum penalties for such offences are not explicitly stated in the provided text but could include substantial financial penalties and imprisonment depending on the severity of the breach and its impact on aviation safety.