AD/AC-CLA/6 - Wing Struts Carry-Through Tube

Overview

The Civil Aviation Regulations 1998, enacted by the Australian Government, address the need for stringent safety measures in the operation and maintenance of civil aircraft. This legislation, overseen by the Civil Aviation Safety Authority, ensures that all aircraft, including those of the A-9 series, adhere to specific safety directives to prevent potential failures that could compromise flight safety. A significant directive under this regulation pertains to the inspection and maintenance of the wing struts carry-through tube, crucial for structural integrity. The policy objective is to ensure the continued airworthiness of aircraft by mandating regular and thorough inspections, repairs, and replacements of critical components to mitigate the risk of in-flight failures. Compliance with these directives is mandatory, ensuring that any necessary actions are completed within specified timeframes post the enactment date of the directive.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, outlines the Civil Aviation Safety Authority's (CASA) Schedule of Airworthiness Directives, focusing on the maintenance and inspection requirements for aircraft parts. This particular directive, AD/AC-CLA/6, applies to all models A-9, A-9A and A-9B aeroplanes equipped with wing struts that include a carry-through tube running through the hopper. The directive mandates the inspection and maintenance of the fibreglass wrapped carry-through tube to prevent failure, thereby ensuring the safety of these aircraft. The requirement is to visually inspect the wrapping for cracks, remove any cracked wrapping to check for corrosion, and replace the tube if corrosion exceeds specified thresholds. The maintenance must be carried out within 25 hours’ time in service after a specified date and at every major inspection thereafter. The regulation applies to all such aircraft operating within Australia, overseen by CASA to ensure compliance with these safety directives. The directive sets out specific inspection and repair procedures, including detailed steps for locating the tube, inspecting for defects, and the precise method for applying a protective coating and rewrapping the tube with specified materials. This legislation does not explicitly mention exclusions or exemptions, indicating that the requirements apply universally to the specified aircraft models within its jurisdictional reach. Subordinate instruments may extend or further detail the application of these regulations, but the primary directive is clear in its stipulations for maintaining the integrity of the wing struts carry-through tubes.

Key Provisions

The Civil Aviation Regulations 1998, specifically under Part 39 and the schedule of airworthiness directives, address the maintenance and safety requirements for certain aircraft parts. For instance, in AD/AC-CLA/6, the focus is on the wing struts carry-through tube of A-9 series aeroplanes (Section 1). The directive mandates that the hopper top must be removed to visually inspect the fibreglass wrapped carry-through tube located 625 mm aft of the hopper forward bulkhead and 150 mm below the hopper surface (Section 2). The inspection must check for any cracks in the fibreglass wrapping. If any cracks are found, the wrapping must be removed to inspect the main carry-through tube for corrosion (Section 2). The regulations require that if corrosion is detected and it exceeds a depth of 0.25 mm in one location or 2% of the tube's cross-sectional area, the main carry-through tube must be replaced (Section 3). The nominal cross-sectional area of the tube is specified as 262.5 sq. mm. After corrosion removal, the tube must be finished with two coats of zinc chromate primer, followed by rewrapping it with a fibreglass laminate using a minimum of three layers of MIL-C-9084 glass cloth or equivalent and chemical-resistant resin such as Reichbold 33-402 (Section 3). Local equivalents may be used in place of the specified materials. The obligations under these regulations require aircraft operators and maintenance personnel to adhere strictly to the inspection and repair schedules. Compliance is mandatory unless the required actions have already been completed. The directive specifies that inspections and necessary repairs must be performed within 25 hours’ time in service after 12 December 1978 and subsequently at every major inspection (Section Compliance). Failure to comply with these requirements can lead to significant safety risks, as the main carry-through tube is critical for the structural integrity of the wing struts. Violating these regulations can result in severe consequences. Under the Civil Aviation Act 1988, non-compliance with airworthiness directives can be considered an offence, leading to penalties. The maximum penalty for such offences includes fines and imprisonment, depending on the severity of the breach. Civil penalties can also be imposed, including substantial fines, and in some cases, criminal prosecution may follow. These stringent measures underscore the importance of adhering to the airworthiness directives to ensure the safety and reliability of aircraft operations.